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3. New trends in food- and waterborne viral outbreaks

Author

Radin Dragoslava

Subjects
Noroviruses, foodborne, waterborne, outbreak, Biology (General), QH301-705.5
Abstract

Current trends in food- and waterborne viral diseases have been reviewed. Awareness and surveillance of viral food and waterborne pathogens is generally not sufficient, with emphasis placed on noroviruses, hepatitis A virus, rotaviruses and newly emerging viruses. In addition, previously unknown food-borne pathogens, many of which are zoonotic, are constantly emerging. Food can be contaminated with a virus either at the source via contaminated water, or at the point of service by infected food handlers. Viruses can spread by water, direct person-to-person contact, airborne droplets or vomit, and they can persist in the environment as a source of continuing infection despite disinfection efforts. Food production and supply practices change, and food-borne pathogens seem able to exploit novel opportunities, for example fresh produce, and generate new food safety and public health challenges. [Projekat Ministarstva nauke Republike Srbije, br. III 46009]

Published
2014
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4. Human norovirus transmission due to contaminated fresh fruit and vegetables

Author

Radin Dragoslava

Subjects
Noroviruses, transmission, fruit, vegetables, gastroenteritis, Biology (General), QH301-705.5
Abstract

Almost any ready-to-eat fruit or vegetable that has been contaminated with pathogens, either from the environment, human or animal feces or through storage, processing and handling, could potentially cause disease. This problem is particularly associated with the occurrence of human intestinal viruses, especially noroviruses, which are of major epidemiological significance as a common cause of both epidemic and sporadic non-bacterial gastroenteritis in humans. Many outbreaks of viral gastroenteritis associated with fresh fruit and vegetables have been described. The rise in incidence of human norovirus outbreaks may be the result of increased consumption of fresh produce, availability of new commodities, export/import and transport around the globe, changes in production practices, improved reporting and detection methods. [PR Projekat Ministarstva nauke Republike Srbije, br. III 46009]

Published
2012
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7. The influence of the food surface and matrix on norovirus detection by RT-qPCR

Author

Radin, Dragoslava, Radin, Dragoslava, Živković, Ivana, Radin, Dragoslava, Radin, Dragoslava, and Živković, Ivana

Abstract

Human noroviruses are predominant cause of epidemic and sporadic food-borne gastroenteritis in industrialized countries. Priority food categories, vehicles of viruses in many reported outbreaks, beside shellfish are food of plant origin including berries, lettuce, tomatoes and green onions. These items, as well as deli ham are often components of many ready-to-eat foods. The aim of this study was to assess the effect of different food matrices on norovirus detection. Stool sample with previously determined concentration of norovirus GII particles, was used to inoculate surface of lettuce, tomatoes, green onions and deli ham slices. For virus RNA extraction the direct method was used followed by RT-qPCR assay with SYBR green one-step kit and degenerate MON primers for the detection of GII norovirus. Obtained mean Ct values and Ct alterations calculated for each level of inoculation revealed that tomato had no inhibitory effect on NoV GII detection, followed by one log decrease of RT-PCRU due to properties of green onions, and two log decrease for lettuce and deli ham slices. The adsorption of viruses to different solid surfaces depends on their complexity and food surface factors such as presence of hydrophobic domains and acid/base groups, virus specific ligands, etc. This is important since many fruits and vegetables have complex surfaces that prevent the removal of viruses by simple washing and may decrease desiccation effects that could lead to virus inactivation.

Published
2016

8. Noroviruses in food chain production

Author

Radin, Dragoslava, Radin, Dragoslava, Radin, Dragoslava, and Radin, Dragoslava

Abstract

Viruses, predominantly noroviruses, are progressively identified as the leading cause of foodborne diseases worldwide. In the Europe Union they have been determined as a main cause of foodborne outbreaks in 2014, while in the United States viruses are responsible for 58% (5.5 million) of foodborne illnesses annually. Noroviruses, the etiological agent of foodborne gastroenteritis belong to the Caliciviridae family, genus Norovirus which is genetically classified into 6 established geno-groups (GI to GVI). Human noroviruses are icosahedral nonenveloped RNA viruses, approximately 27 to 38 nm in diameter, and contain single-stranded positive-sense RNA genomes size from 7.4 to 8.3 kb and 3 open reading frames. Viruses are transmitted by contaminated food or water, through person-to-person contact, and by cross-contamination from surfaces. Foods at risk includes those which need extensive handling, mostly ready-to-eat foods that do not undergo further processing, and those exposed to environmental contamination, such as seafood and fresh produce. Contamination with human norovirus can happen throughout the entire food production chain: (i) at the primary production (due to fecal polluted water in the harvest area/ irrigation/ water used to dilute pesticide, organic-based fertilizers and potential root uptake of pathogens following internalization); (ii) during harvest (contact with human feces or fecal soiled materials, cross-contamination with equipment and food handlers poor hygiene practice); (iii) at the post-harvest stage by inappropriate practices during handling, processing, preparation, storage, distribution (by infected food handlers, spraying with contaminated water, cross-contamination during washing process) and (iv) at the point of sale/consumption (by infected food handlers, cross-contamination with polluted working instruments or surfaces previously contaminated by infected food handlers or food items). Strategies to reduce human noroviruses in the food ch

Published
2016

9. Antiviral activity of medicinal plants extracts against foodborne norovirus

Author

Živković, Ivana, Živković, Ivana, Šavikin, Katarina, Zdunić, Gordana, Živković, Jelena, Bigović, Dubravka, Menković, Nebojša, Radin, Dragoslava, Živković, Ivana, Živković, Ivana, Šavikin, Katarina, Zdunić, Gordana, Živković, Jelena, Bigović, Dubravka, Menković, Nebojša, and Radin, Dragoslava

Abstract

Medicinal plant extracts (MPE) have a broad antimicrobial activity, including antiviral effects. In our study, eleven dry extract of ten different medicinal plant prepared with two solvents (5%, dimethyl sulfoxide (DMSO) and 30% ethanol in 5% DMSO) in different concentrations have been examined for anti-noroviral activity. The reduction of norovirus > 1 log10 genome equivalents (GE) has been obtained with 1 mg/mL of Aronia melanocarpa leaf extract (AMLE), dried wine Prokupac (WPE) and Hypericum perforatum extract (HyPE). Some of MPE i.e. HyPE, Aronia melanocarpa fruit extract (AMFE) and Punica granatum (PPE) showed better activity when dissolved in 30% ethanol with 5% DMSO. All results of anti-noroviral activity of tested MPE which achieve lt 0.5 log10 GE are considered as not effective.

Published
2018

11. New trends in food- and waterborne viral outbreaks

Author

Radin, Dragoslava, Radin, Dragoslava, Radin, Dragoslava, and Radin, Dragoslava

Abstract

Current trends in food- and waterborne viral diseases have been reviewed. Awareness and surveillance of viral food and waterborne pathogens is generally not sufficient, with emphasis placed on noroviruses, hepatitis A virus, rotaviruses and newly emerging viruses. In addition, previously unknown food-borne pathogens, many of which are zoonotic, are constantly emerging. Food can be contaminated with a virus either at the source via contaminated water, or at the point of service by infected food handlers. Viruses can spread by water, direct person-to-person contact, airborne droplets or vomit, and they can persist in the environment as a source of continuing infection despite disinfection efforts. Food production and supply practices change, and food-borne pathogens seem able to exploit novel opportunities, for example fresh produce, and generate new food safety and public health challenges.

Published
2014

12. Human norovirus transmission due to contaminated fresh fruit and vegetables

Author

Radin, Dragoslava, Radin, Dragoslava, Radin, Dragoslava, and Radin, Dragoslava

Abstract

Almost any ready-to-eat fruit or vegetable that has been contaminated with pathogens, either from the environment, human or animal feces or through storage, processing and handling, could potentially cause disease. This problem is particularly associated with the occurrence of human intestinal viruses, especially noroviruses, which are of major epidemiological significance as a common cause of both epidemic and sporadic non-bacterial gastroenteritis in humans. Many outbreaks of viral gastroenteritis associated with fresh fruit and vegetables have been described. The rise in incidence of human norovirus outbreaks may be the result of increased consumption of fresh produce, availability of new commodities, export/import and transport around the globe, changes in production practices, improved reporting and detection methods.

Published
2012

13. Significance of internal amplification control for the detection of human noroviruses from different food samples by real-time RT-PCR

Author

Radin, Dragoslava, Radin, Dragoslava, Savić, M.D., D'Souza, D.H., Radin, Dragoslava, Radin, Dragoslava, Savić, M.D., and D'Souza, D.H.

Abstract

Among human enteric viruses, the noroviruses (NoVs) are of a major epidemiological significance as a common cause of both epidemic and sporadic non-bacterial gastroenteritis in humans. According to the recent CDC data, NoVs caused most illnesses (58%) through consumed contaminated food especially soft fruits, vegetables and RTE foods. The most effective methods for virus detection in food samples are those based on nucleic acid amplification. However, two major obstacles that influence routine virus detection in foods include the low efficiency of concentration and nucleic acid extraction procedures and the presence of inhibitors from food matrix to the molecular reactions. Most false negatives are consequence of inefficient virus and/or nucleic acid extraction and of inhibition of the RT-PCR reaction. To verify whether amplification reactions have functioned correctly, implementation of internal amplification controls (IACs) is essential. For this purpose, previously constructed IACs for application with highly reactive degenerate primers (COG) for the detection of human NoVs genogroups GI and GII by real-time RT-PCR were tested. Twenty-five grams of raspberries, lettuce, cherry tomatoes, green onions and deli meat have been artificially inoculated with norovirus GI and GII positive stool samples. IACs were incorporated in all real-time RT-PCR assays, and simultaneous amplification of both target and RNA IAC was achieved after optimization without decreasing detection levels of virus. In this study it has been shown that IACs amplification was unaffected by the viral RNA extraction procedure from different food items, which could potentially be a source of diverse inhibitors.

Published
2012

14. Characterization and determination of bacteriocins produced by autochthonous Lactococci

Author

Mirković, Nemanja, Radulović, Zorica, Kojić, Milan, Nikšić, Miomir, Lozo, Jelena, Radin, Dragoslava, Mirković, Nemanja, Mirković, Nemanja, Radulović, Zorica, Kojić, Milan, Nikšić, Miomir, Lozo, Jelena, Radin, Dragoslava, and Mirković, Nemanja

Abstract

Lactic acid bacteria (LAB), synthesized a number of different antimicrobial substances among wich bacteriocins are the most important. Bacteriocins of LAB, with regard to the GRAS (Generaly Recognized As Safe) status of LAB, can be used as food preservatives, but also in pharmaceutical industry as an alternative or supplement to antibiotic therapy. A large number of species of the genus Lactococcus sp., not only to play a key role in the production of fermented food where they contribute to specific aroma and structure of fermented products, but also they have ability to synthesize different bacteriocins. Bacteriocins are small, ribosomaly synthesized peptides or proteins with relatively narrow spectrum of antimicrobial activity which is limited to closely related species, and producer has specific mechanism of self-protection. The aim of this thesis was to select a natural isolates of lactococci which have ability to produce bacteriocins. Then, to characterize the selected bacteriocins, to determine their antimicrobial potential and analyze potential applications in the food industry. The strains Lactoccus lactis ssp. lactis BGBM50, LMG2081 and BGBU1-4, whose bacteriocins were analyzed in this paper, were determined using conventional microbiological-biochemical tests and molecular methods of determination (sequencing of gene for 16S rRNA). Testing ability of lactococci to produce bacteriocins, was performed using bacteriocin activity assay in which as sensitive strains were used lactococci, lactobacilli and pathogenic bacteria. Determinations of bacteriocins were performed using cross-resistance test between bacteriocin producer strains and by using PCR method with specific primers for the knowing genes coding for different bacteriocins. It was found that the strain L. lactis ssp. lactis BGBM50 synthesizes bacteriocin named BacBM50. Plasmid curing experiments showed that genes for bacteriocin production are located on the big plasmid of 145,5 kb..., Bakterije mlečne kiseline (BMK), sintetišu veliki broj antimikrobnih jedinjenja, među kojima značajno mesto zauzimaju bakteriocini. Bakteriocini, s obzirom na GRAS (Generalno Prepoznati Kao Sigurni) status koje imaju BMK, mogu se primenjivati kao konzervansi hrane, ali i u farmaceutskoj industriji kao alternativa ili dodatak antibiotskoj terapiji. Veliki broj vrsta roda Lactococcus sp., pored toga što zauzima ključnu ulogu u proizvodnji fermentisane hrane gde doprinose specifičnoj aromi i strukturi fermentisanih proizvoda, ima i sposobnost sinteze različitih bakteriocina. Bakteriocini su mali, ribozomalno sintetisani peptidi ili proteini koji imaju relativno uzak spektar antimikrobne aktivnosti koja je ograničena na blisko srodne vrste i prema kojoj soj proizvođač ima mehanizam specifične samozaštite. Cilj ove teze, bio je da se odaberu prirodni izolati laktokoka koji imaju sposobnost produkcije bakteriocina. Zatim, da se odabrani bakteriocini okarakterišu, da se utvrdi njihov antimikrobni potencijal i analizira potencijalna primena u prehrambenoj industriji. Sojevi L. lactis ssp. lactis BGBM50, LMG2081 i BGBU1-4, čiji su bakteriocini analizirani u ovom radu, determinisani su korišćenjem klasičnih mikrobiološko-biohemijskih metoda, kao i metoda molekularne determinacije (sekvenciranjem gena za 16S rRNK). Testiranje laktokoka na sposobnost produkcije bakteriocina, urađeno je primenom bakteriocinskih testova sa senzitivnim sojem laktokoka, laktobacila i patogenih bakterija kao indikatorima. Determinacija bakteriocina je određena testovima unakrsne inhibicije između sojeva bakteriocin proizvođača, korišćenjem PCR metoda sa specifičnim prajmerima za gene koji kodiraju različite bakteriocine i analizom sekvence genoma...

Published
2016

15. Ispitivanje antimikrobnih osobina hitozana na rast Listeria monocytogenes u povrću

Author

Klaus, Anita, Nikšić, Miomir, Radin, Dragoslava, Zlatković, Branislav, Katić, Vera, Jovanović, Gordana D., Klaus, Anita, Nikšić, Miomir, Radin, Dragoslava, Zlatković, Branislav, Katić, Vera, and Jovanović, Gordana D.

Abstract

Zadatak ove doktorske disertacije bio je da se utvrdi antimikrobna aktivnost hitozana u formi omotača i filmova na sojeve Listeria monocytogenes ATCC 19112 i Listeria monocytogenes ATCC19115 u sveže sečenom, minimalno prerađenom povrću. Antimikrobna svojstva hitozana analizirana su u različitim vrstama hrane kao što su sveže sečeno povrće: kupus, šargarepa i crna rotkva ali i majonez, koji se često koristi za pripremu salata sa povrćem. Osim antimikrobne aktivnosti hitozana, ispitivan je uticaj filmova hitozana na promenu pH vrednosti, sadržaj rastvorljive suve materije i senzorne karakteristike ispitivanog povrća. U cilju realizacije postavljenih zadataka izrađeni su različiti modeli omotača i filmova sa hitozanom. Omotači hitozana su pripremljeni sa mlečnom ili sirćetnom kiselinom tako da je ukupna koncentracija hitozana u njima iznosila 0,25%; 0,5% ili 1%. Filmovi hitozana su pripremljeni sa dodatkom želatina tako da je u njima postignuta konačna koncentracija od 0,5%; 1% i 2% hitozana. U cilju poboljšanja antimikrobne aktivnosti u filmove je dodato etarsko ulje mente ili timijana u koncentraciji od 0,1% i 0,2%. Odabir ovih ulja izvršen je na osnovu rezultata ispitivanja antimikrobne aktivnosti etarskih ulja koja su pokazala da etarska ulja timijana i mente imaju najefikasnije dejstvo na testirane bakterijske sojeve. Analizom dobijenih rezultata utvrđeno je da testirani sojevi bakterija imaju različitu sposobnost preživljavanja na ispitivanim vrstama povrća. Najveća inhibicija rasta ispitivanih bakterijskih sojeva postignuta je kod crne rotkve i šargarepe. Sam kupus ne ispoljava inhibitorni efekat na rast ispitivanih bakterija, već značajno doprinosi razvoju ovih bakterija. Antimikrobna aktivnost omotača hitozana zavisi od upotrebljene koncentracije hitozana, vrste organske kiseline koja je upotrebljena kao rastvarač, kao i od vrste povrća u kome se omotači primenjuju. Najizraženija inhibicija bakterijskih sojeva postignuta je u crnoj rotkvi i šargarepi, sa 1% om, The objective of this doctoral thesis was to determine the antimicrobial activity of chitosan in the form of coatings and films against the strains of Listeria monocytogenes ATCC 19112 and Listeria monocytogenes ATCC 19115 in fresh-cut, minimally processed vegetables. The antimicrobial properties of chitosan were analyzed in different types of food such as fresh cut vegetables: cabbage, carrot and black radish and mayonnaise, which is often used to prepare the salad with vegetables. In addition to the antimicrobial activity of chitosan, the influence of chitosan films on pH changes, content of soluble solids and sensory properties of tested vegetables, have been investigated. In order to realize of given tasks, different coatings and films with the chitosan were made. Chitosan coatings were prepared with lactic or acetic acid, so that the total concentrations of chitosan coatings have been 0.25%; 0.5% or 1%. Films of chitosan were prepared with the addition of gelatin and final concentrations of chitosan have been 0.5%; 1% and 2%. In order to improve the antimicrobial activity of the films, essential oil of mint or thyme in a concentration of 0.1% and 0.2% were added. The choice of these oils was made on the basis of the antimicrobial activity of thyme and mint essential oils which have been shown as the most effective against the tested bacterial strains. The analysis of the results showed that the tested strains of bacteria have different viability in the tested types of vegetables. The highest growth inhibition of tested bacterial strains was achieved in the black radish and carrots. Cabbage alone does not exhibit an inhibitory effect on growth of the bacteria, but also significantly contributes to the development of these bacteria. Antimicrobial activity of chitosan coatings depends on the concentration of chitosan used, type of organic acid which is used as a solvent, and the type of vegetable in which the coatings were applied. The highest inhibition of growth

Published
2016

16. Karakterizacija i determinacija bakteriocina autohtonih laktokoka

Author

Radulović, Zorica, Kojić, Milan, Nikšić, Miomir, Lozo, Jelena, Radin, Dragoslava, Mirković, Nemanja L., Radulović, Zorica, Kojić, Milan, Nikšić, Miomir, Lozo, Jelena, Radin, Dragoslava, and Mirković, Nemanja L.

Abstract

Bakterije mlečne kiseline (BMK), sintetišu veliki broj antimikrobnih jedinjenja, među kojima značajno mesto zauzimaju bakteriocini. Bakteriocini, s obzirom na GRAS (Generalno Prepoznati Kao Sigurni) status koje imaju BMK, mogu se primenjivati kao konzervansi hrane, ali i u farmaceutskoj industriji kao alternativa ili dodatak antibiotskoj terapiji. Veliki broj vrsta roda Lactococcus sp., pored toga što zauzima ključnu ulogu u proizvodnji fermentisane hrane gde doprinose specifičnoj aromi i strukturi fermentisanih proizvoda, ima i sposobnost sinteze različitih bakteriocina. Bakteriocini su mali, ribozomalno sintetisani peptidi ili proteini koji imaju relativno uzak spektar antimikrobne aktivnosti koja je ograničena na blisko srodne vrste i prema kojoj soj proizvođač ima mehanizam specifične samozaštite. Cilj ove teze, bio je da se odaberu prirodni izolati laktokoka koji imaju sposobnost produkcije bakteriocina. Zatim, da se odabrani bakteriocini okarakterišu, da se utvrdi njihov antimikrobni potencijal i analizira potencijalna primena u prehrambenoj industriji. Sojevi L. lactis ssp. lactis BGBM50, LMG2081 i BGBU1-4, čiji su bakteriocini analizirani u ovom radu, determinisani su korišćenjem klasičnih mikrobiološko-biohemijskih metoda, kao i metoda molekularne determinacije (sekvenciranjem gena za 16S rRNK). Testiranje laktokoka na sposobnost produkcije bakteriocina, urađeno je primenom bakteriocinskih testova sa senzitivnim sojem laktokoka, laktobacila i patogenih bakterija kao indikatorima. Determinacija bakteriocina je određena testovima unakrsne inhibicije između sojeva bakteriocin proizvođača, korišćenjem PCR metoda sa specifičnim prajmerima za gene koji kodiraju različite bakteriocine i analizom sekvence genoma..., Lactic acid bacteria (LAB), synthesized a number of different antimicrobial substances among wich bacteriocins are the most important. Bacteriocins of LAB, with regard to the GRAS (Generaly Recognized As Safe) status of LAB, can be used as food preservatives, but also in pharmaceutical industry as an alternative or supplement to antibiotic therapy. A large number of species of the genus Lactococcus sp., not only to play a key role in the production of fermented food where they contribute to specific aroma and structure of fermented products, but also they have ability to synthesize different bacteriocins. Bacteriocins are small, ribosomaly synthesized peptides or proteins with relatively narrow spectrum of antimicrobial activity which is limited to closely related species, and producer has specific mechanism of self-protection. The aim of this thesis was to select a natural isolates of lactococci which have ability to produce bacteriocins. Then, to characterize the selected bacteriocins, to determine their antimicrobial potential and analyze potential applications in the food industry. The strains Lactoccus lactis ssp. lactis BGBM50, LMG2081 and BGBU1-4, whose bacteriocins were analyzed in this paper, were determined using conventional microbiological-biochemical tests and molecular methods of determination (sequencing of gene for 16S rRNA). Testing ability of lactococci to produce bacteriocins, was performed using bacteriocin activity assay in which as sensitive strains were used lactococci, lactobacilli and pathogenic bacteria. Determinations of bacteriocins were performed using cross-resistance test between bacteriocin producer strains and by using PCR method with specific primers for the knowing genes coding for different bacteriocins. It was found that the strain L. lactis ssp. lactis BGBM50 synthesizes bacteriocin named BacBM50. Plasmid curing experiments showed that genes for bacteriocin production are located on the big plasmid of 145,5 kb...

Published
2016

17. Bakteriofagi kao agensi u kontroli formiranja biofilmova Pseudomonas aeruginosa

Author

Radin, Dragoslava, Raičević, Vera, Teodorović, Smilja, Nikšić, Miomir, Knežević, Petar, Vujović, Bojana A., Radin, Dragoslava, Raičević, Vera, Teodorović, Smilja, Nikšić, Miomir, Knežević, Petar, and Vujović, Bojana A.

Abstract

Pseudomonas aeruginosa je štapićasta, asporogena bakterija, široko rasprostranjena u sredinama kao što su zemljište, voda, ljudski i životinjski organizmi, biljke i otpad. P. aeruginosa poseduje jedan cirkularni hromozom koji je smešten u citoplazmi ćelije, kao i više plazmida značajnih za patogena svojstva ove bakterije. Genom P. aeruginosa je veličine 5,2 do 7,1 Mbp, u kome je ukupna zastupljenost guanina i citozina oko 65%. Najveći broj genetskih i genomskih analiza P. aeruginosa je usmeren ka kliničkim izolatima, dok je mnogo manja pažnja posvećena izolatima iz životne sredine, zbog čega je manje od 10% genomskih sekvenci deponovanih u Nacionalnom Centru za Biotehnološke Informcije (NCBI) izolata poreklom iz životne sredine. Jedna od glavnih kompetitivnih prednosti P. aeruginosa u preživljavanju u različitim uslovima spoljašnje sredine je sposobnost formiranja biofilmova, a brojna istraživanja su pokazala da većina izolata ima ovu sposobnost. Izučavanju biofilmova se u poslednje vreme poklanja značajnija pažnja u oblastima mikrobiologije hrane, vode, životne sredine kao i medicinske mikrobiologije. Prisustvo biofilmova u životnom okruženju čoveka, različitim sistemima za transport industrijske, površinske vode, vode za navodnjavanje kao i medicinskoj opremi i pomagalima, čine biofilmove aktuelnom temom u medicini, farmaciji, ali i u kontekstu higijene hrane. Eliminacija bakterijskih biofilmova je izuzetno težak proces, zbog toga postoji potreba da se razvijaju altenativni načini za sprečavanje formiranja i kontrolu biofilmova. Polazeći od napred navednog, osnovni naučni cilj ove doktorske disertacije je sagledavanje mogućnosti primene bakteriofaga u kontroli formiranja biofilmova, kao i uticaja na već formirane biofilmove sojeva vrste Pseudomonas aeruginosa, pri definisanim ekološkim uslovima u pogledu temperature, pH i koncentracije NaCl. Iz uzoraka sedimenta, aktivnog mulja, površinske vode, vode za piće i zemljišta sa različitih lokaliteta izolovano je 30 izo, Psudomonas aeruginosa is rod shape, asporogenous bacteria, wide spread in soil, water, human and animal organisms, plants and solid wastes. P. aeruginosa has one circular chromosome which is placed into the cell’s cytoplasm, as well as more plasmids which are significant for pathogen characteristics of this bacterium. Genome size of P. aeruginosa is from 5.2 to 7.1 Mbp and Guanine and Cytosine content in the genome is approximately 65 %. The number of the genetic and genome’s analyses of P. aeruginosa is directed to the clinical isolates and significantly lower attention is devoted to the isolates from environment. The consequence is that the less than 10 % of the genome’s sequences deposited in the National Centre for Biotechnology Information (NCBI) in USA are with environmental origin. One of the main competitive advantages of P. aeruginosa survival under different environmental conditions is biofilm forming ability. Numerous investigations are shown that main part of isolates have this ability. Researches of the biofilm are paying great attention in last decades, especially in the following fields: microbiology of food, water, environment, as well as medical microbiology. Because of biofilm presence in the human environment, different facilities for water transport in industry, surface waters, water for irrigation purposes, medical equipment and tools, biofilm became very important goal for investigation in medicine, pharmacy and food hygiene. Elimination of the bacteria’s biofilms is extremely hard process and because that, alternative methods for avoiding biofilm formation, as well as biofilm control are very necessary. Taking in mind all these previously mentioned facts, investigation of Pseudomonas aeruginosa strains diversity selected from environment and its biofilm forming ability and forming of the identified bacteria strains collection is established as main scientific goal of this Ph.D. thesis. The goal of this Ph.D. thesis is investigations of possibi

Published
2016

18. Spoilage microflora of vacuum packaged frankfurters and influence on the growth of Listeria monocytogenes

Author

Radin, Dragoslava, Radin, Dragoslava, Niebuhr, SE, Dickson, J.S., Radin, Dragoslava, Radin, Dragoslava, Niebuhr, SE, and Dickson, J.S.

Abstract

Spoilage microflora present on vacuum packaged frankfurters is in most cases, result of post processing contamination, at the same time this is the primary cause of contamination with Listeria monocytogenes. Since spoilage organisms are present in the same environment as a pathogen, the aim was to determine their microbial interference. Approximately 100 CFU/cm2 of a five-strain mixture of L. monocytogenes was co inoculated onto frankfurters with different concentrations (103 and 106 CFU/cm2) of spoilage microflora (bacteria from genera Lactobacillus, Bacillus, Micrococcus, and Hafnia). The frankfurters were vacuum packaged and stored at 10°C for up to 48 days. The spoilage microflora that developed during storage consisted predominantly of lactic acid bacteria. The growth of mesophilic aerobic bacteria and LAB was very similar, with populations reaching 8.0 log CFU/cm2 within 24 days and final population of >9 log CFU/cm2 within 48 days. The presence of spoilage microflora extended the lag phase of L. monocytogenes until 24 days and significantly decreased pathogen level to 4 and 3 log CFU/cm2, in samples inoculated with initial concentration 103 CFU/cm2 and 106 CFU/cm2 of spoilage microflora, respectively. L. monocytogenes populations were significantly higher (P lt 0.05) in the reference sample (no spoilage microflora) and reached a maximum population of 5.9 log CFU/cm2 after 34 days. These results imply that competing microorganisms present on the processed meat may inhibit the growth of L. monocytogenes in the package., Proizvodi od mesa, uključujući ready-to-eat (RTE) proizvode kao što su viršle, povezani su sa pojavom oboljenja listerioze. Do kontaminacije ovih proizvoda patogenom bakterijom Listeria monocytogenes najčešće dolazi nakon proizvodnje i primenjenog termičkog tretmana a pre pakovanja. S ozirom da se mnogi od ovih proizvoda mogu konzumirati bez ponovnog zagrevanja mogu biti uzrok listerioze. Imajuću u vidu činjenicu da su u vakuum pakovanim viršlama prisutni i mikroorganizmi koji mogu izazivati kvar, cilj je bio da se ispita njihov međusobni uticaj. Viršle su inokulisane mešavinom pet sojeva L. monocytogenes u koncentraciji 100 CFU/cm2 i različitim koncentracijama bakterija koje pripadaju rodovima Lactobacillus, Bacillus, Micrococcus i Hafnia. Viršle su, zatim vakuum pakovane i skladištene na 10°C 48 dana. U odsustvu kompetitivnih bakterija, patogena bakterija L. monocytogenes je dostigla maksimalnu koncentraciju od 5.9 log CFU/cm2 i imala lag fazu koja je iznosila 7 dana. Ovi podaci doprinose činjenici da vakuum pakovane viršle čine veoma dobru sredinu za rast i preživljavanje L. monocytogenes. Mikroflora koja se razvijala tokom skladištenja se uglavnom sastojala od bakterija mlečne kiseline čiji je razvoj bio vrlo sličan razvoju mezofilne aerobne mikroflora, i dostizao maksimalnu populaciju >9 log CFU/cm2. Prisustvo ove mikroflore je produžilo lag fazu L. monocytogenes do 24 dana i značajno smanjilo broj patogena do 4 odn. 3 log CFU/cm2, u uzorcima koji su inokulisani početnom koncentracijom 103 CFU/cm2 odnosno 106 CFU/cm2 bakterija kvara. Ovi rezultati ukazuju da kompetitivna mikroflora može inhibirati rast L. monocytogenes na proizvodima od mesa u vakuum pakovanju.

Published
2007

19. Impact of the population of spoilage microflora on the growth of Listeria monocytogenes on frankfurters

Author

Radin, Dragoslava, Radin, Dragoslava, Niebuhr, SE, Dickson, JS, Radin, Dragoslava, Radin, Dragoslava, Niebuhr, SE, and Dickson, JS

Abstract

Approximately 100 CFU/cm(2) of a five-strain mixture of Listeria monocytogenes was coinoculated onto frankfurters with three different concentrations (10(2), 10(4), and 10(6) CFU/cm(2)) of an undefined spoilage microflora derived from commercial frankfurters. The frankfurters were vacuum packaged and stored at 10 degrees C for up to 48 days. The populations of L. monocytogenes, aerobic mesophilie bacteria, lactic acid bacteria, and Enterobacteriaceae were determined at various time intervals during storage. After 14 days, the population of L. monocytogenes was highest when grown with a spoilage microflora population of 10(2) CFU/cm(2), and this trend continued until 48 days. Throughout the entire storage period, the populations of L. monocytogenes at any concentration of inoculated spoilage microflora rarely differed by more than 0.5 log CFU/cm(2), and the maximum observed difference as 1.1 log CFU/cm(2) at 40 days. The growth rate of L. monocytogenes was approximately the same at all concentrations of the inoculated spoilage microflora. These results suggest that the concentration of spoilage microflora present on the original processed meat may have a slight impact on the growth of L monocytogenes in the package.

Published
2006

20. Maturation of kajmak in controlled conditions

Author

Radin, Dragoslava, Radin, Dragoslava, Djerovski, Jelena, Radulović, Zorica, Radovanović, Mira, Pudja, Predrag, Radin, Dragoslava, Radin, Dragoslava, Djerovski, Jelena, Radulović, Zorica, Radovanović, Mira, and Pudja, Predrag

Abstract

Kajmak was produced according to the production procedure proposed by Puđa Starčević and Radovanović, which enables standard composition and characteristics, as well as high microbiological quality of the product. Directly after collection, kajmak was inoculated with the mixture of lactic acid bacteria which are used as starter cultures: Lactococcus lactis ssp. lactis, Lc. lactis ssp. cremoris, Lc. lactis ssp. lactis bv. diacetylactis and Leuconostoc mesenteroides ssp. cremoris. As protective cultures, the following species were used: Lactobacillus rhamnosus and Propionbacterium freudenreichii ssp. shermanii. Maturation of kajmak took place on 12°C and 18°C. Kajmak surface was protected by coating with the wax layer. Kajmak composition and dynamics of starter growth were analyzed during 30 days of ripening. pH value of kajmak was decreasing in the first days of maturation and draped to 4.7 for 7 and 15 days when maturation took place at 18°C and 12"C, respectively. Growth of aroma producing bacteria was increasing from 106 cfu/g after inoculation to max. value of 108 cfu/g of kajmak. The kajmak samples which were ripened at the 12°C showed max. number of aroma producing bacteria at the 15th day of ripening, while at 18°C max. number was achieved after two days of maturation., Proizvodnja kajmaka obavljena je po tehnološkom postupku Puđa, Starčević Radovanović (12) koji obezbeđuje standardni sastav i karakteristike, kao i visoku mikrobiološku ispravnost proizvoda. Kajmak je neposredno po izuzimanju inokulisan smešom starter kultura bakterija mlečne kiseline Lactococcus lactis ssp. lactis, Lc. lactis ssp. cremoris, Lc. lactis ssp. lactis bv. diacetylactis i Leuconostoc mesenteroides ssp. Cremoris, a kao protektivne kulture korišćene su vrste Lactobacillus rhamnosus i Propionbacterium freudenreichii ssp. shermanii. Zrenje kajmaka je obavljeno na temperaturama 12°C i 18°C u ambalaži pri čemu je po površini kajmaka nanesen sloj zaštitnog premaza u cilju zaštite od atmosferskih uticaja. Kajmak je ispitivan u toku jednomesečnog zrenja u pogledu hemijskog sastava i dinamike razvoja startera. pH vrednost kajmaka je opadala intenzivno u početku zrenja i ustalila se na vrednosti od oko 4,7 posle 7 dana zrenja na 18°C, odnosno 15 dana zrenja na 12°C. Razvoj aromogenih bakterija mlečne kiseline imao je trend porasta i povećavao se od 106 cfu/g nakon inokulacije do maksimalne vrednosti od oko 108 cfu/g kajmaka. U kajmaku koji je imao zrenje na 12°C maksimalni broj aromogenih bakterija postignut je 15. dana zrenja, dok je na 18°C maksimalan broj postignut već posle dva dana zrenja kajmaka.

Published
2005

21. Bacteriophages, persistent problem in manufacturing fermented milk products

Author

Radin, Dragoslava, Radin, Dragoslava, Radin, Dragoslava, and Radin, Dragoslava

Abstract

Lactic acid bacteria play a central role in manufacturing fermented milk products. The most common cause of failure of this process is bacteriophage infection, which cause lysis of the starter bacteria. They inhibit or completely prevent acidification by the starter culture. A number of measures to prevent phage infection, including implementation of hygienic procedures, rotation of starter cultures, isolation of resistant mutants and using of media to suppress phage multiplication have been instituted The early detection of phage contamination in dairy fermentation could be important strategy to prevent and control phage development., Bakterije mlečne kiseline imaju osnovnu ulogu u proizvodnji fermentisanih proizvoda od mleka. Upotrebom starter kultura usmerava se tok fermentacije Međutim, često dolazi do neželjenih promena, usporavanje acidifikacije smanjenja viskoziteta proizvoda, nedostatka arome, preterane ili nedovoljne proizvodnje gasa, potpunog prestanka fermentacije i gubitka u prinosu Smatra se da je za 70-80% ovih problema odgovorna infekcija bakteriofagima koji izazivaju lizis bakterija. Identifikovana su dva osnovna izvora kontaminacije fagima u mlekarama: prisustvo bakterija mlečne kiseline u sirovom mleku i lizogene starter kulture. U nastojanjima da se uspešno resi problem bakteriofagnih infekcija razrađeno je više mera zaštite: fizičke (bolja sanitacija, čista okolina, zaštićene sirarske kade), fiziološke (upotreba podloga koje sprečavaju rast bakteriofaga starter kulture bez prisutnih bakteriofaga, rotacija starter kultura) i genetički program kojim se obezbeđuju starter kulture povećane otpornosti na infekciju bakteriofagima. Zbog stalne pretnje od ozbiljnih fagnih infekcija u mlekarama je potrebno neprekidno praćenje prisustva faga, što istovremeno predstavlja i osnovnu zaštitnu meru.

Published
2002

22. Sinorhizobium meliloti strains, inoculated with some lytic bacteriophage isolates

Author

Radin, Dragoslava, Radin, Dragoslava, Radin, Dragoslava, and Radin, Dragoslava

Abstract

Lysis by bacteriophages is one of the factors influencing growth and survival of rhizobia in soil. As specific bacteriophages, infective for the root-nodule bacterium Sinorhizobium meliloti, are wide spread and may be found in almost all alfalfa fields, it was of theortical and practical importance to examine phage-host interaction. In these investigations 64 strains of S. meliloti, with diverse origin and characteristics, were included. Ten specific bacteriophages, have been selected from those isolated by enrichment of soils. The infective ability of the bacteriophages was assessed accoding to the occurrence of plaques on inoculated double-layer agar plates. According to the differential susceptibility of individual S. meliloti strains to each phage, strains were divided into three different groups: 1. Bacterial strains (6) resistant to all tested bacteriophages; 2. Bacterial strains (12) susceptible to all tested bacteriophages; and 3. Bacterial strains (46) susceptible to some of the tested bacteriophages. Some of active nitrogen fixers from the first group could be useful in the nodulation of alfalfa plants., Lizis prouzrokovan bakteriofagima je jedan od faktora koji utiče na porast i preživljavanje bakterija, simbioznih azotofiksatora u zemljištu. Kako su bakteriofagi specifični za kvržičnu bakteriju Sinorhizobium meliloti široko rasprostranjeni i mogu se naći u skoro svim lucerištima, bilo je od teorijskog i praktičnog značaja ispitati interakciju između faga i bakterija, njihovih domaćina. U ova istraživanja uključeno je 64 sojeva S. meliloti, različitog porekla i karakteristika. Izabrano je deset specifičnih bakteriofaga, izolovanih metodom obogaćivanja zemljišta. Infektivnost bakteriofaga za bakterijske sojeve određivana je na osnovu pojave plakova u inokulisanom dvostrukom agaru. Na osnovu različite osetljivosti svakog pojedinačnog soja S. meliloti prema testiranim izolatima bakteriofaga, bakterijski sojevi su podčijeni u tri grupe: 1. Bakterijski sojevi (6) rezistentni prema svim testiranim bakteriofagima; 2. Bakterijski sojevi (12) osetljivi prema svim testiranim bakteriofagima; i 3. Bakterijski sojevi (46) osetljivi prema nekim od testiranih bakteriofaga. Neki sojevi koji pripadaju prvoj grupi, a pokazuju visoku aktivnost u azotofiksaciji mogu biti korisni u nodulaciji licerke.

Published
2001

24. Importance of aerobic stability in silages

Author

Ivetić, Aleksandra, Djordjević, Nenad, Radin, Dragoslava, Stojić, Petar, Grubić, Goran, and Stojanović, Bojan

Subjects
lactic acid bacteria, molds, aerobna stabilnost, kvasci, yeasts, silaža, plesni, silage, bakterije mlečne kiseline, aerobic stability
Abstract

Aerobic stability is a term that indicates the length of the time that silage remains cool and does not spoil after it is exposed to air. Therefore, rapid removal of air from forage mass and prevention of air infiltration into the silage during storage and feed out are the important factors that determine the duration of the silage aerobic stability. The measurement of CO2 production, separately or in combination with other measurements such as temperature, pH, lactic acid and volatile fatty acids and microbial examination, can serve as a reliable laboratory method to determine the duration of silages aerobic stability in silages. This paper work has aim to point on the importance of determination the duration of aerobic stability of silages, because quality changes and losses in the case of aerobic degradation. Aerobna stabilnost je termin kojim se definiše dužina vremena za koje silaža ostaje hladna i ne kvari se po izlaganju vazduhu. Zbog toga, brzo otklanjanje vazduha iz silaže tokom siliranja i smanjeno izlaganje vazduhu po otvaranju silosa su dva važna faktora koji određuju dužinu aerobne stabilnosti silirane stočne hrane. U proceni aerobnog kvarenja,merenje proizvodnje CO2, odvojeno ili u kombinaciji sa drugim parametrima kao što je temperatura silaže, pH vrednost, sadržaj mlečne i sirćetne kiseline i mikrobiološka analiza, mogu se koristiti kao pouzdani laboratorijski metod. Ovaj rad ima za cilj da ukaže na značaj procene vremena trajanja aerobne stabilnosti stočne hrane,zbog promena i gubitaka kvaliteta pri aerobnoj degradaciji.

Published
2013

25. Saccharomyces boulardii the only probiotic yeast

Author

Obradović, Dragojlo B., Radin, Dragoslava, and Radulović, Zorica

Subjects
Saccharommyces boulardi, probiotik, antidiarrheal effect, probiotic, antidijarealni efekat
Abstract

Yeasts as eukaryotes do have a more diverse enzymatic profile than lactic acid bacteria. They provide protection against pathogenic bacteria and toxic compounds by surface binding. Saccharomyces boulardii, a non-pathogenic yeast, has been used both as a preventative and therapeutic agent for the treatment of a variety of diarrheal diseases. Experimental studies clearly demonstrate that S. boulardii has specific probiotic properties, and recent data has opened the door for new therapeutic uses of this yeast. Today, a considerable number of pharmaceutical preparations (capsules, powders, tablets, pellets) containing probiotic yeast Saccharomyces boulardii cells are commercially available, and are marketed mainly via pharmacies. Also, the application of the Saccharomyces boulardii as a probiotic microorganism seems promising especially in milk and yogurts, the production of amounts of alcohol and gas formation, however, are for the moment major problem. . Probiotici danas predstavljaju pravi hit u proizvodnji funkcionalne hrane i parafarmaceutskih proizvoda. Po pravilu, svi ovi proizvodi zasnivaju se na bakterijama mlečne kiseline (BMK) i bifidobakterijama, a rezultati velikog broja istraživanja opravdavaju njihovu sve veću primenu. Međutim, kod parafarmaceutskih proizvoda često je prisutan kvasac Saccharommyces boulardii koji je intenzivno testiran u pogledu probiotskih svojstava, a koji je prema najnovijim molekularnim ispitivanjima veoma blizak vrsti Saccharomyces cerevisiae. Prema nekim autorima, radi se o varijetetu navedene vrste. Saccharommyces boulardii pokazuje terapeutska svojstva kod dijareja izazvanih delovanjem antibiotika, prisustvom Clostridium dificile, pojave iritabilnog kolona, kod osoba obolelih od AIDSa, itd. Kako je navedena vrsta nađena u kulturama čajne gljive kombuhe i kefira, učinjeni su prvi pokušaji u pogledu primene ove vrste u proizvodnji fermentisanih mlečnih napitaka u zajednici sa BMK. Iako nije u stanju da koristi laktozu, Saccharommyces boulardii je koristio prisutne organske kiseline, galaktozu i glukozu nastalu u toku metabolizma BMK. Pojava gasa i alkohola i dalje predstavlja glavni problem za dalju primenu ove vrste, ali istraživanja treba nastaviti jer se potencijalno mogu dobiti proizvodi sa visokom nutritivnom vrednošću. .

Published
2009

26. The study of autochthonous lactic acid bacteria from white brined cheeses

Author

Radulović, Zorica, Radin, Dragoslava, Barać, Miroljub, Djerovski, Jelena, Paunović, Dušanka, and Obradović, Dragojlo

Subjects
white brined cheeses, autochthonous lactic acid bacteria, autohtone bakterije mlečne kiseline, starter culture, beli sirevi u salamuri
Abstract

White brined cheeses are made traditionally, without the addition of starter cultures and fermentation occurs as a result of lactic acid bacteria naturally present in milk. The aim of the study is to identify strains to be used as starter cultures in commercial cheese production. A total of 65 autochthonous lactic acid bacteria from 15 artisan cheeses were isolated and studied. All strains were tested for their Gram reaction, catalase test, acidification activity, growth ability with 20, 40, 60g NaCl/l, proteolytic ability to hydrolyze β-casein by SDS PAGE electrophoresis and biochemical identification with API 50CHL and API RAPID ID 32 Strep. Biochemical identification showed that mesophilic microflora was dominant and 47,7% of the isolates were classified as Lactococcus, 10,7% as Enterococcus, 35,4% as Lactobacillus and 3,1% as Leuconostoc. Dominant lactocci strain was Lactococcus lactis ssp. lactis (35,4%) but the presence of citrateutilizing bacteria Lactococcus lactis ssp. lactis bv. diacetylactis, as aroma enhancer is significant. For lactobacilli dominant strain was Lactobacillus para. paracasei (21,5%). Isolated strains varied significantly in acid production, from very fast and good acid producers (some strains of Lactococcus lactis ssp. lactis reduced the pH lt 4.8), to very poor ones. All isolated lactic acid bacteria grew in 20 and 40g NaCl/L, while 25 isolates grew in 60g NaCl/L. Isolates showed different proteolytic ability to hydrolyze β-casein. Some of them very extensively degraded β-casein, the others demonstrated inferior activity. Screening important attributes of autochthonous lactic acid bacteria demonstrated that several bacterial strains are potentially useful as new starter cultures for industrial production of cheeses. . Beli sirevi u salamuri se prave tradicionalnim postupkom, bez dodavanja starter kultura, pa se proces fermentacije odigrava pod uticajem bakterija mlečne kiseline koje su prirodno prisutne u mleku. Cilj ovog rada je pronalaženje sojeva bakterija mlečne kiseline, koji bi mogli da se primene kao starter kulture u komercijalnoj proizvodnji sireva. Iz 25 uzoraka sireva izolovano i okarakterisano je 65 izolata autohtonih bakterija mlečne kiseline. Za sve sojeve je ispitano: bojenje po Gramu, katalaza test, acidogena aktivnost, sposobnost rasta na 20, 40, 60g NaCl/l, proteolitička sposobnost razgradnje β-kazeina SDS PAGE elektroforezom i biohemijska identifikacija primenom API 50CHL i API RAPID ID 32 Strep. Biohemijskom identifikacijom je utvrđeno da je mezofilna mikroflora dominantna, a 47,7% izolata je identifikovano kao Lactococcus, 10,7% kao Enterococcus, 35,4% kao Lactobacillus i 3,1% Leuconostoc. Dominantne laktokoke su bile Lactococcus lactis ssp. lactis (35,4%), a, takođe, značajno je bilo prisustvo citrat pozitivnih bakterija Lactococcus lactis ssp. lactis bv. diacetylactis, kao producenata arome. Od laktobacila dominantni su bili sojevi Lactobacillus para. paracasei (21,5%). Izolovani sojevi su se značajno razlikovali u acidifikacionoj sposobnosti, od veoma brzih i dobrih producenata kiseline (neki sojevi Lactococcus lactis ssp. lactis su snižavali pH lt 4.8) do veoma slabih acidogena. Svi izolati bakterija mlečne kiseline su dobro rasli u prisustvu 20 i 40g NaCl/l, dok je 25 izolata raslo u prisustvu 60g NaCl/L. Izolati su pokazali različitu proteolitičku sposobnost hidrolize β-kazeina. Neki su veoma intezivno hidrolizovali β-kazein, dok su drugi bili potpuno inferiorni u pogledu ove sposobnosti. Ispitivanjem karakteristika koje su važne za starter kulture pokazalo se da među autohtonim bakterijama mlečne kiseline ima i bakterija koje bi mogle da se primene kao nove starter kulture u industrijskoj proizvodnji sireva. .

Published
2009

27. Characterization of kombucha microflora in fermented milk beverages

Author

Radulović, Zorica, Iličić, Mirela D., Radin, Dragoslava, Paunović, Dušanka, Mitrović, Nemanja L., Petrušić, Milica M., and Obradović, Dragojlo B.

Subjects
tea fungus, kvasci, sirćetne bakterije, acetic acid bacteria, fermentisani mlečni napici, fermented milk beverages, čajna gljiva, yeast
Abstract

Application of tea fungus has been increasing world-wide as it is useful for obtaining fermented tea beverages with potential therapeutic characteristics. It is known that tea fungus is composed of acetic acid bacteria and yeasts, but involved species in these consortia are various, depending on its origin and the geographical region from which it comes from. By identifying present microflore of some tea fungus, it is possible to show its typicality and differentiate it from others. Considering that obtaining tea beverages by application of tea fungus has been known for a long time, possibility of fermented milk beverages appeared as an innovative question. Hence, in this paper isolation and identification of tea fungus microflore, where presence of acetic acid bacteria Acetobacter aceti, Acetobacter pasteurianus, Gluconobacter xylinum and yeasts belonged to the genera Saccharomyces, Candida and Kloeckera was noted, has been carried out. For the making of fermented milk beverages, subsequent inoculums were applied: fermented tea, retentate obtained by ultrafiltration and concentrate obtained by evaporation in milk with different fat content (0.9%, 1% and 2.2%) and different concentration (10%, 15% fermented tea and retentates and 1.5%, 3% concentrates). Growth ability of acetic acid bacteria and yeasts in 10 different fermented milk beverages was examined, and best activity was detected in the sample with 2.2% milk fat. During 15 days storage of the fermented milk beverages at 4°C, viability of acetic acid bacteria and yeasts was very good. From microbiological aspect, application of tea fungus in fermented milk beverages production could be the base for obtaining new fermented milk beverages, but additional research of the chemical, technological, nutritive and sensorial aspects are necessary. . Primena čajna gljive je sve više rasprostranjena u svetu i koristi se za dobijanje fermentisanog čajnog napitka, sa potencijalnim terapeutskim svojstvima. Poznato je da čajnu gljivu čini simbioza sirćetnih bakterija i kvasaca, ali su prisutne vrste veoma raznovrsne, zavisno od porekla i geografskog regiona. Identifikacijom prisutne mikroflore čajne gljive može se pokazati tipičnost same gljive, po kojoj se razlikuje od drugih. S obzirom da je dobijanje čajnog napitka primenom čajne gljive poznato veoma dugo, kao inovacija se javlja pitanje mogućnosti dobijanja fermentisanog mlečnog napitka. U tom smislu, u radu je izvršena izolacija i identifikacija mikroflore čajne gljive, pri čemu je utvrđeno prisustvo sirćetnih bakterija Acetobacter aceti, Acetobacter pasteurianus, Gluconobacter xylinum i kvasaca koji pripadaju rodovima Saccharomyces, Candida i Kloeckera. Za dobijanje fermentisanog mlečnog napitka, primenjeni su inokulumi: fermentisani čaj, retentat dobijen ultrafiltriranjem i koncentrat dobijen uparavanjem, u mleku sa različitim sadržajem mlečne masti (0,9%,1% i 2,2%) i različitim koncentracijama (10% i 15% čajnog napitka i retentata i 1,5% i 3% koncentrata). Ispitana je sposobnost rasta sirćetnih bakterija i kvasaca u deset različitih varijanti fermentisanih mlečnih napitaka, gde je najbolja aktivnost bila u prisustvu 2,2% mlečne masti a vijabilnost sirćetnih bakterija i kvasaca pokazala se veoma dobrom u toku 15 dana čuvanja fermentisanog mlečnog napitka na 4°C. Sa mikrobiološkog aspekta, primena čajne gljive u proizvodnji fermentisanih mlečnih napitaka daje osnov za dobijanje novog fermentisanog mlečnog proizvoda, ali neophodna su dalja istraživanja sa hemijskog, tehnološkog, nutritivnog i senzornog aspekta. .

Published
2009

28. Cheeses with medicinal and aromatic plants, produced in Europe

Author

Maćej, Ognjen, Seratlić, Sanja V., Jovanović, Snežana, Radin, Dragoslava, Vučić, Tanja, and Miloradović, Zorana

Subjects
aromatic herbs, lekovito bilje, aromatično bilje, cheeses with herbs, sirevi sa biljem, medicinal plants
Abstract

In the production of cheeses, the application of medicinal and aromatic herbs is reflected both in improving sensory characteristics, and increasing stability and shelf life of final products. Also, the final product gets new physiological properties, of the so-called functional food. The antimicrobial properties of aromatic and medical plants essential oils are well established against wide spectra of microbes including bacteria, viruses, yeasts and fungi. Cheeses with medicinal and aromatic herbs are traditionally produced in Turkey (mostly soft fresh cheese and white cheese in brine). However, there is a large assortment of this kind of cheeses that is produced throughout Europe, from the soft and semi-soft to semi-hard and hard cheeses. The main characteristic of all these cheeses is the use of medicinal and aromatic plants from the unique geographic area for each European country. There are numerous medical and aromatic plants used in cheese production. These include: mint, thyme, basil, parsley, sage, oregano, dill, pepper, cinnamon, cumin, ginger, rosemary, garlic, pepperoni, pepper, bay, mulberry, cloves, tarragon, fenugreek, celery, shallot, nettle, etc. Also, in many countries these cheeses are traditionally produced from cow, sheep and goat or mixed milk. In France, a country known for the production of many different cheese varieties, a large number of cheeses from goat milk is traditionally produced. Belgium is not far behind, where the large number of cheese varieties is produced as well as in the Netherlands and Germany. . U proizvodnji sireva, primena lekovitog i aromatičnog bilja se ogleda kako u poboljšanju senzornih karakteristika, tako i povećanju stabilnosti i roka trajanja finalnog proizvoda. Takođe se dobija proizvod sa novim fiziološkim svojstvima, tzv. Funkcionalna namirnica. Uloga ovog bilja u produžetku roka tajanja sireva se, između ostalog, ogleda u tome što etarska ulja mnogih lekovitih i aromatičnih biljaka imaju antimikrobnu aktivnost prema velikom broju bakterija, virusa, kvasaca i plesni, i predstavljaju potencijalno bogat izvor novih biocida i preservativa. Sirevi sa lekovitim i začinskim biljem tradicionalno se proizvode u Turskoj, i to su u pitanju pretežno meki beli sirevi i beli sirevi u salamuri. Ipak, postoji veliki asortiman ovih sireva koji se proizvode širom Evrope, od mekih, preko polumekih i polutvrdih do tvrdih. Ono što je karakteristično za sve ove sireve je da se upotrebljava lekovito i aromatično bilje, karakteristično za dato geografsko područje. Lekovito i aromatično bilje, koje se koristi u proizvodnji sireva, je brojno. Tu spadaju: nana, timijan, bosiljak, peršun, žalfija, origano, mirođija, biber, cimet, kim, đumbir, ruzmarin, beli luk, feferoni, aleva paprika, list lovora, list duda, karanfilić, estragon, piskavica, celer, vlašac, kumin, kopriva, itd. Takođe, u mnogim zemljama se već tradicionalno proizvode sirevi sa lekovitim i aromatičnim biljem, i to kako od kravljeg, tako i od ovčjeg i kozjeg ili mešanog mleka. Francuska, kao zemlja poznata po proizvodnji različitih varijeteta sireva, tradicionalno proizvodi veliki broj ovih sireva od kozjeg mleka. Ni Belgija mnogo ne zaostaje po asortimanu, a veliki broj ovih sireva proizvode i Holandija i Nemačka. .

Published
2009

29. Potentials of application adjunct cultures in cheese production

Author

Obradović, Dragojlo, Radin, Dragoslava, and Radulović, Zorica

Subjects
autoliza, sekundarna mikroflora, bacteriocin, adjunct culture, cheese ripening, probiotik, autolysis, probiotic, dopunske kulture, zrenje sira
Abstract

Attempts to select lactic acid bacteria for use as adjuncts have been made, with the purpose of both controlling off-flavors in cheese and enhancing the development of good cheese flavor. A promising application of bacteriocin-producing LAB is a control of adventitious spoilage microorganisms and their use as cell-lysis inducing agents to increase proteolysis and flavor formation in cheese. It is also proposed that cheese could be an effective vehicle for delivery of probiotics to the consumer. Mikroorganizmi imaju ključnu ulogu u toku proizvodnje i zrenja sireva. U tim procesima velika pažnja se poklanja izboru starter kultura, ali se često zaboravlja aktivnost takozvane sekundarne mikroflore koja je specifično vezana za određena svojstva pojedinih vrsta sireva. Ta mikroflora može da posluži kao potencijalni izvor sojeva koji bi ulazili u sastav takozvanih "dopunskih" kultura čija je funkcija poboljšanje senzornih osobina i skraćenje zrenja sireva. U dopunske kulture mogle bi da spadaju i one koje sadrže sojeve koji sintetišu bakteriocine u cilju sprečavanja razvića neželjene mikroflore ili koji ubrzavaju proces liziranja ćelija čime se oslobađa veliki broj intracelularnih enzima bitnih za procese zrenja. Isto tako i primena probiotika u proizvodnji sireva privlači sve veću pažnju, jer su se sirevi pokazali kao dobri vektori za prenos probiotika.

Published
2007

30. The research of kajmak quality: Chemical, microbiological and sensor aspect

Author

Djerovski, Jelena, Radulović, Zorica, Radin, Dragoslava, Radovanović, Mira, and Pudja, Predrag

Subjects
crobiological, mikrobiološka ispravnost, chemical composition, kajmak, hemijski sastav
Abstract

Kajmak is autohthonous product, which is traditionally made like farmhouse fermented milk product by farmers. In such conditions of production, quality of kajmak is usually very variable and nonstandard. The aim of this paper was to research chemical composition, autohthonous microflora, microbiological and sensory quality of kajmak samples, which had been collected from green markets and supermarkets on Belgrade territory. Chemical composition and sensory quality of tested kajmak samples showed great difference, while according to microbiological analyses, not all samples were suitable for human consumption. Industrial production of kajmak, under controlled conditions and usage of starter cultures could be the solution for getting good standard quality of this dairy product. Also, this could lead to better marketing possibilities for domestic market and for export. Kajmak predstavlja autohtoni proizvod, čija je proizvodnja pretežno zastupljena u seoskim domaćinstvima i zasniva se na tradicionalnom postupku dobijanja. U takvim uslovima, proizvod je veoma neujednačenog i nestandardizovanog kvaliteta. Cilj rada je bio da se ispita hemijski sastav autohtona mikroflora i mikrobiološka ispravnost, kao i senzorne karakteristike uzoraka kajmaka koji se mogu naći u slobodnoj prodaji na teritoriji Beograda. U pogledu hemijskog sastava i senzornog kvaliteta svi ispitivani uzorci kajmaka pokazuju veliku raznolikost, dok u mikrobiološkom pogledu uzorci ne odgovaraju važećim normama Pravilnika, te kao takvi ne bi smeli da se stavljaju u promet. Rešenje pitanja standardizacije procesa proizvodnje i kvaliteta kajmaka moglo bi biti u industrijskoj proizvodnji koja bi dala proizvod dobrog standardnog kvaliteta. To bi omogućilo i veći plasman kajmaka kako na domaćem, tako i stranom tržištu.

Published
2006

31. Autohtona mikroflora sjeničkog sira

Author

Radulović, Zorica, Radin, Dragoslava, and Obradović, Dragojlo B.

Subjects
lactic acid bacteria, autohtona mikroflora, Sjenica cheese, bacteria, food and beverages, autochthonous microflora, bakterije mlečne kiseline, sjenički sir
Abstract

Autochthonous isolates of lactic acid bacteria and enterococci, from Sjenica cheese had been isolated and identified. From 10 samples of Sjenica cheese that were traditionally produced without starter cultures, 53 thermophile mesophile and citrate (+) isolates were isolated using selective media (MRS agar, M17 agar, LDCagar i LDV agar). According to Gram staining, cell morphology and catalase test, it was determined that all isolates were pure culture of G (+) and catalase (-) bacteria, 21 bacilli and 35 cocci. For the purpose of diferentiation enterococci and lactococci, growth of all cocci bacteria was examined on 6,5% NaCI, pH 9,6 and heat treatment 60°C 20 min. Out of 35 cocci isolates, 7 isolates were able to grow at these conditions. Identification by API CHL 50 test for lactobacilli and RAPID ID 32 Strep for cocci, showed that isolates were Lactococcus lactis ssp. lactis Lactobacillus paracasei ssp. paracasei, Lactobacillus plantarum, Lactococcus lactis ssp. lactis boiv. dicetylactis, Lactobacillus curvatus, Lactobacillus brevis, Leuconostoc sp. i Enterococcus sp. Dominant lactococci strain was Lactococcus lactis ssp. lactis (35,85%) and for lactobacilli Lactobacillus paracasei ssp. paracasei (18,86%). Strains from genus Enterococcus sp. had the rate of 13,20%. U radu su izdvojeni i identifikovani izolati bakterija mlečne kiseline i enterokoka iz sjeničkog sira, proizvedenog na tradicionalan način, bez dodavanja starter kulture. Iz 10 uzoraka sjeničkog sira izdvojeno je 53 termofilna, mezofilna i citrat+ izolata na odgovarajućim selektivnim podlogama (MRS agar, M17 agar, LDCagar i LDV agar). Postupkom bojenja po Gramu, mikroskopskim pregledom i katalaza testom je utvrđeno da svi izolati predstavljaju čiste kulture Gram-pozitivnih i katalaza-negativnih bakterija pri čemu je utvrđeno da je 21 izolat štapićastog, a 35 okruglastog oblika. Radi razdvajanja enterokoka od laktokoka, za sve okruglaste forme je ispita-na sposobnost rasta pri 6,5% NaCI, pH 9,6 i nakon termičkog tretmana na 60°C 20 minuta je utvrđeno da od 35 izolata okruglastog oblika, 7 izolata podnosi navedene uslove. Determinacijom dobijenih izolata primenom API sistema i to za štapičaste oblike API CHL50testa, a za okruglaste oblike RAPID ID 32 Strep sistema, utvrđeno je da izolati pripadaju vrstama Lac-tococcus lactis ssp. lactis, Lactobacillus paracasei ssp. paracasei Lactobacillus plantarum, Lactococcus lactis ssp. lactis boiv. dicetylactis Lactobacillus curvatus, Lactobacillus brevis, Leuconostoc sp. i Enterococcus sp. Ubedljivo najveću zastupljenost je imala okruglasta vrsta Lactococcus lactis ssp. lactis (35,85%), a od štapićastih, vrsta Lactobacillus paracasei ssp. Paracasei (18,86%). Vrste roda Enterococcus sp. bile su zastupljene sa 13,20 %.

Published
2006

32. The cellular fatty acid composition of Bradyrhizobum japonicum and Sinorhizobium meliloti strains

Author

Gojgić-Cvijović, Gordana, Radin, Dragoslava, Miličić, Bogić, and Đoković, Dejan

Subjects
Bradyrhizobium japonicum, fatty acid analysis, Sinorhizobium meliloti
Abstract

Microbial fatty acid analysis represents a simple and rapid method for identification of strains mainly for taxonomic purpose. Fatty acid composition in the whole cells and lipopolysaccharides in Rhizobiaceae were studied to point at biochemical events of the nitrogen-fixing symbiosis too. In this study the fatty acid profiles of six strains Bradyrhizobium japonicum and three strains Sinorhizobium meliloti were analyzed. The strains were isolated from soils of Serbia and obtained from collection of Institute of Soil Science. Methyl esters of total fatty acids were prepared from lyophilised biomass using toluene-methanol-sulphuric acid mixture and analyzed using GC-MS method. In Sinorhizobium meliloti strains the main components are 16:0, 218:1. cy-19:0 and in lesser proportion are cy 17:0. 17:0. 18:0. 16:1, 3-OH 14:0, 15:0 and 14:0 fatty acids. The results obtained are in accordance with previously reported data. The absence of 20:3(0 6,9,12cis and 3-OH 16:0 fatty acids in all chromatograms might be explained by differences in derivation method or growth medium used. The ineffective strain (Nod+Fix-) contains remarkable less cyl7:0 acid. Dominant components in Bradyrhizobium japonicum strains are 118:1 and 16:0 fatty acids. Also cy19:0, 18:0 and 16:1 components were detected and certain shifts in the amount of these minor components observed. However, on the basis of our results there is no correlation between the relative content of particular fatty acid and the fixing effectiveness of tested strain. Analiza masnih kiselina mikroorganizama, jednostavna i brza metoda za identifikaciju sojeva, često se koristi u taksonomiji. Masne kiseline celih ćelija i lipopolisaharida kod Rhizobiaccae su od posebnog značaja za proučavanje simbiotske azot o fiksacije. U ovom radu su analizirani profili masnih kiselina šest sojeva Bradvrhizobium japonicum i tri soja Sinorhizobium meliloti. Sojevi su ili izolovani iz uzoraka zemlje rz Srbije ili potiču iz kolekcije Instituta za zemljište. Metil estri ukupnih masnih kiselina su pripremani digestijom liofilizovane biomase u smesi toluol-metanol-sumporna kiselina i analizirani GC-MS metodom. Kod sojeva Sinorhizobium meliloti glavne komponente su 16:0, Z18; l, cj'19:0 i u manjem procentu cy 17:0, 17:0, 18:0, 16:1, 3-OH 14:0, 15:0 i 14:0 masne kiseline. Dobijeni rezultati su u saglasnosti sa literaturnim podacima, a odsustvo 20:3co 6,9.12r/s i 3-OH 16:0 masnih kiselina u svim hromatogramima se može objasniti razlikama u sastavu podloge korišćene za gajenje i načinu pripreme metil estara. Neefektivni soj (Nod+Fix-) sadrži znatno manje cy 17:0 kiseline. Dominantne komponente kod sojeva Bradyrhizobium japonicum su Z18: l i 16:0 masne kiseline. Pored toga detektovane su i cy 19:0, 18:0 and 16:1 masne kiseline. Uočene razlike u koncentraciji ovih minornih komponenata su verovatno posledica različite brzine rasta, pa na osnovu dobijenih rezultata nema korelacije između sadržaja masnih kiselina i efektivnosti azotofiksacije kod ispitivanih sojeva.

Published
2006

33. Determination of autochthonous lactic acid bacteria from kashkaval cheese

Author

Radulović, Zorica, Radin, Dragoslava, and Obradović, Dragojlo B.

Subjects
Kashkaval cheese, lactic acid bacteria, autohtona mikroflora, autochthonous microflora, bakterije mlečne kiseline, kačkavalj
Abstract

Autochthonous isolates of lactic acid bacteria and enterococci from Kashkaval cheese had been isolated and identified. From 6 samples of Kashkaval cheese that were traditionally produced without starter cultures, 27 isolates were isolated using selective media (MRS agar, M17 agar) and two incubation temperatures (37ºC and 43ºC). According to Gram staining, cell morophology and catalase test, it was determined that all isolates were pure culture of G (+) and catalase (-) bacteria, 12 bacilli and 15 cocci. For the purpose of diferentiation between enterococci and lactococci, growth of all cocci bacteria was examined on 6,5% NaCl, pH 9,6 and heat treatment 60ºC 20 min. Out of 15 cocci isolates, 6 isolates were able to grow at these conditions. Acidogenic activity was determinated by measuring pH values of 1% inoculated reconstituted skim milk during 24 hours. Researched isolates showed significant difference in lactic acid production. Ten isolates had good acidogenic activity (pH 4,12-4,90) and seventeen isolates were weak producers (pH 5,10 - 6,48). Identification by API CHL 50 test for lactobacilli and RAPID ID 32 Strep for cocci, showed that isolates were Lactobacillus delbrueckii ssp. delbrueckii, Lactobacillus casei, Lactobacillus plantarum Lactobacillus fermentum, Lactobacillus curvatus, Streptococcus salivarius ssp. thermophilus, Lactococcus lactis ssp. lactis, Lactococcus lactis ssp. cremoris, Enterococcus faecium i Enterococcus durans. U radu su izdvojeni i okarakterisani izolati bakterija mlečne kiseline i enterokoka iz kačkavalja, proizvedenog bez dodavanja starter kulture. Iz 6 uzoraka kačkavalja različite starosti izdvojeno je 27 izolata na odgovarajućim selektivnim podlogama MRS i M17 agaru i temperaturama rasta od 37ºC i 43ºC. Postupkom bojenja po Gramu, mikroskopskim pregledom i katalaza testom je utvrđeno da svi izolati predstavljaju čiste kulture Gram-pozitivnih i katalaza-negativnih bakterija, pri čemu je utvrđeno da je 12 izolata štapićastog, a 15 okruglastog oblika.. Radi razdvajanja enterokoka od bakterija mlečne kiseline, za sve okruglaste forme je ispitana sposobnost rasta pri 6,5% NaCl, pH 9,6 i nakon termičkog tretmana na 60ºC 20 minuta utvrđeno je da od 15 izolata okruglastog oblika, 6 izolata podnosi navedene uslove. Acidogena aktivnost je određena merenjem pH vrednosti rekonstituisanog obranog mlaka sa 1 % inokuluma u toku 24 sata, pri čemu je utvrđeno da se izolati značajno razlikuju u sposobnosti stvaranja kiseline. Deset izolata je pokazalo dobru acidogenu sposonost (pH 4,12-4,90), dok je 17 izolata slabo produkovalo kiselinu (pH 5,10 - 6,48). Determinacijom dobijenih izolata primenom API sistema i to za štapićaste oblike API CHL 50 testa, a za okruglaste oblike RAPID ID 32 Strep sistema, utvrđeno je da izolati pripadaju vrstama: Lactobacillus delbrueckii ssp. delbrueckii, Lactobacillus casei Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus curvatus Streptococcus salivarius ssp. thermophilus, Lactococcus lactis ssp. lactis Lactococcus lactis ssp. cremoris, Enterococcus faecium i Enterococcus durans.

Published
2006

34. Characterization of autochthonous lactic acid bacteria genus Lactococcus

Author

Radulović, Zorica, Radin, Dragoslava, Barać, Miroljub, Djerovski, Jelena, and Obradović, Dragojlo

Subjects
lactic acid bacteria, acidogena sposobnost, autoch­thonous cheese, autohtoni sir, proteolytic activity, proteolitička aktivnost, bakterije mlečne kiseline, acidogenic ability
Abstract

Lactic acid bacteria strains isolated from autochthonous cheeses were researched. In products such as these, where starters were not added fermentation occurs as a result of natural flora present in the surrounding environment. Thirty thermophilic, mesophilic and citrate+ LAB strains were isolated by selective medium (LM17 agar and LDC agar) from 5 samples of autochthonous cheeses. They were exposed to further analysis and identification. After examination by Gram test and catalase test, 12 strains of LAB, were selected for further analysis. On the basis of lactose fermentation and acid production in 1% reconstituted skim milk, 6 homofermentative strains were selected, that also had good acidogenic activity. Their proteolytic ability to hydrolyze B-casein was examined by SDS polyacrilamid electrophoresis, where these strains showed different proteolytic activity. Determination of these strains by API Rapid ID 32 Strep tests showed that 4 strains belong to the Lactococcus lactis ssp. tech's and 2 strains to the Lactococcus lactis ssp. lactis biovar. diacetylactis. Rad je obuhvatio karakterizaciju bakterija mlečne kiseline izolovanih iz autohtonih sireva proizvedenih na tradicionalan način, bez dodavanja starter kultura. Iz 5 uzoraka sira izvršena je izolacija 30 termofilnih mezofilnih i cit-rat+ sojeva BMK na odgovarajućim selektivnim podlogama (LM17 agar i LDC agar). Od izdvojenih čistih kultura, nakon određivanja Gram reakcije i katalaza testa, izabrano je 12 sojeva za dalja ispitivanja. Na osnovu načina fermentacije laktoze (homo-heterofermentacija)i acidogene sposobnosti praćene u 1% rekonstituisanom obranom mleku u toku 24 sata, selekcionisano je 6 sojeva koji su pokazali homofermentativnu aktivnost i dobru acidogenu sposobnost. Za ove sojeve je ispitana proteolitička aktivnost u odnosu na β-kazein, pomoću SDS poliakrilamidne elektroforeze, koja je pokazala međusobne razlike u sposobnosti razgradnje β-kazeina. Na kraju je izvršena njihova identifikacija pomoću API Rapid ID 32 Strep testa za laktokoke, i utvrđeno je da 4 soja pripadaju vrsti Lactococcus lactis ssp. lactis, a dva soja vrsti Lactococcus lactis ssp. lactis biovar. diacetylactis.

Published
2005

35. Bakterije mlečne kiseline izolovane iz sjeničkog sira

Author

Radulović, Zorica, Martinović, Aleksandra, Radin, Dragoslava, and Obradović, D.

Subjects
lactic acid bacteria, acidogena sposobnost, acidogenuos ability, Sjenica cheese, food and beverages, bakterije mlečne kiseline, sjenički sir
Abstract

Lactic acid bacteria strains isolated from autochthonous cheeses of Sjenica were investigated. In those products, where starters were not added fermentation occurred as a result of natural flora present in the surrounding environment. Forty thermophilic, mesophilic and citrat+ LAB strains were isolated by selective mediums (MRS agar, LM17 agar and LDC agar) from 5 samples of Sjenica-cheeses. They were exposed to further analysis and identification. After examination by Gram test and catalase test, 13 strains of LAB, were selected for further analysis. On the basis of lactose fermentation way and acid production in 1% reconstituted skimed milk, 6 strains were selected. Determination of these strains by API 50 CHL and Rapid ID 32 Strep tests showed that 2 strains belonged to the Lactococcus lactis ssp. lactis, 2 strains to the Lactococcus lactis ssp. cremoris and 2 strains to the Lactobacillus para.paracasei. U radu su izolovani i karakterisani sojevi bakterija mlečne kiseline izdvojeni iz sjeničkog sira, proizvedenog autohtonom tehnologijom, bez dodavanja starter kultura. Iz 5 uzoraka sjeničkog sira izvršena je izolacija 40 termofilnih, mezofilnih i citrat+ sojeva BMK na odgovarajućim selektivnim podlogama (MRS agar, LM17 agar i LDC agar). Ovi sojevi su dalje podvrgnuti ispitivanju na Gram reakciju i katalaza test, posle čega je izabrano 13 sojeva za dalja ispitivanja. Na osnovu načina fermentacije laktoze i acidogene sposonosti praćene u 1% rekonstituisanom obranom mleku selekcionisano je samo 6 sojeva. Determinacijom ovih sojeva pomoću API CHL 50 i Rapid ID 32 Strep testa, pokazalo se da 2 soja pripadaju vrsti Lactococcus lactis ssp. lactis, 2 soja Lactococcus lactis ssp. cremoris i 2 soja vrsti Lactobacillus para.paracasei.

Published
2004

36. Application of probiotics in cheese manufacturing - state, perspective

Author

Obradović, Dragojlo B., Radin, Dragoslava, Pudja, Predrag, and Karić, Andjelka S.

Subjects
cheese, functional food, probiotics, probiotici, sir, funkcionalna hrana
Abstract

Traditionally, the most popular food delivery systems for probiotic strains have been freshly fermented milks, as well as unfermented milks with cultures added. However, in the development of functional dairy products Cheese could offer certain advantages as delivery systems of live probiotics to the gastrointestinal tract, which is the target organ. Cheeses having a higher pH than fermented milks, providing a more stable milieu could support long-term survival. Furthermore, the matrix, high fat content of cheeses may protect the organisms during passage through the gastrointestinal tract. There are relatively few reports concerning cheese as a carrier of probiotics, even though there are small number of probiotic cheeses currently on the market worldwide. Having in mind all of these data it is proposed that cheese could be an effective vehicle for delivery of probiotics to the consumer. Proizvodnja sireva predstavlja jednu od najvitalnijih grana mlekarske industrije sa godišnjom stopom rasta od 2%, čemu sigurno pogoduje i globalizacija svetskog tržišta. Kada je u pitanju primena probiotika u sirarstvu, tu stvari, za razliku od fermentisanih napitaka, nisu dovoljno ispitane. Imajući u vidu pH sireva, oksidoredukcioni potencijal, hemijski sastav, strukturu, puferska svojstva, neosporno je da sirevi mogu biti dobri vektori za prenos probiotika. Međutim, trenutno je suviše mali broj sireva sa probioticima na tržištu, ali zato podaci dobijeni na osnovu eksperimenata deluju ohrabrujuće. S druge strane, nedostatak validnih medicinskih istraživanja o delovanju probiotika koji su konzumirani sa sirevima, takođe čini ovu oblast nedovoljno ispitanom. Ako se ima u vidu da proizvodnja funkcionalne hrane ima permanentnu ekspanziju, a da mlečni proizvodi tu zauzimaju vidno mesto, dâ se očekivati da će i sirevi sa probioticima dati doprinos tom trendu.

Published
2003

37. Sinorhizobium meliloti sojevi inokulisani nekim izolatima litičnih bakteriofaga

Author

Radin, Dragoslava

Subjects
phage-host interaction, lytic bacteriophages, food and beverages, Sinorhizobium meliloti
Abstract

Lysis by bacteriophages is one of the factors influencing growth and survival of rhizobia in soil. As specific bacteriophages, infective for the root-nodule bacterium Sinorhizobium meliloti, are wide spread and may be found in almost all alfalfa fields, it was of theortical and practical importance to examine phage-host interaction. In these investigations 64 strains of S. meliloti, with diverse origin and characteristics, were included. Ten specific bacteriophages, have been selected from those isolated by enrichment of soils. The infective ability of the bacteriophages was assessed accoding to the occurrence of plaques on inoculated double-layer agar plates. According to the differential susceptibility of individual S. meliloti strains to each phage, strains were divided into three different groups: 1. Bacterial strains (6) resistant to all tested bacteriophages; 2. Bacterial strains (12) susceptible to all tested bacteriophages; and 3. Bacterial strains (46) susceptible to some of the tested bacteriophages. Some of active nitrogen fixers from the first group could be useful in the nodulation of alfalfa plants. Lizis prouzrokovan bakteriofagima je jedan od faktora koji utiče na porast i preživljavanje bakterija, simbioznih azotofiksatora u zemljištu. Kako su bakteriofagi specifični za kvržičnu bakteriju Sinorhizobium meliloti široko rasprostranjeni i mogu se naći u skoro svim lucerištima, bilo je od teorijskog i praktičnog značaja ispitati interakciju između faga i bakterija, njihovih domaćina. U ova istraživanja uključeno je 64 sojeva S. meliloti, različitog porekla i karakteristika. Izabrano je deset specifičnih bakteriofaga, izolovanih metodom obogaćivanja zemljišta. Infektivnost bakteriofaga za bakterijske sojeve određivana je na osnovu pojave plakova u inokulisanom dvostrukom agaru. Na osnovu različite osetljivosti svakog pojedinačnog soja S. meliloti prema testiranim izolatima bakteriofaga, bakterijski sojevi su podčijeni u tri grupe: 1. Bakterijski sojevi (6) rezistentni prema svim testiranim bakteriofagima; 2. Bakterijski sojevi (12) osetljivi prema svim testiranim bakteriofagima; i 3. Bakterijski sojevi (46) osetljivi prema nekim od testiranih bakteriofaga. Neki sojevi koji pripadaju prvoj grupi, a pokazuju visoku aktivnost u azotofiksaciji mogu biti korisni u nodulaciji licerke.

Published
2001

38. Autochthonous microflora of Sjenica cheese

Author

Radulović, Zorica, Radulović, Zorica, Radin, Dragoslava, Obradović, Dragojlo B., Radulović, Zorica, Radulović, Zorica, Radin, Dragoslava, and Obradović, Dragojlo B.

Abstract

Autochthonous isolates of lactic acid bacteria and enterococci, from Sjenica cheese had been isolated and identified. From 10 samples of Sjenica cheese that were traditionally produced without starter cultures, 53 thermophile mesophile and citrate (+) isolates were isolated using selective media (MRS agar, M17 agar, LDCagar i LDV agar). According to Gram staining, cell morphology and catalase test, it was determined that all isolates were pure culture of G (+) and catalase (-) bacteria, 21 bacilli and 35 cocci. For the purpose of diferentiation enterococci and lactococci, growth of all cocci bacteria was examined on 6,5% NaCI, pH 9,6 and heat treatment 60°C 20 min. Out of 35 cocci isolates, 7 isolates were able to grow at these conditions. Identification by API CHL 50 test for lactobacilli and RAPID ID 32 Strep for cocci, showed that isolates were Lactococcus lactis ssp. lactis Lactobacillus paracasei ssp. paracasei, Lactobacillus plantarum, Lactococcus lactis ssp. lactis boiv. dicetylactis, Lactobacillus curvatus, Lactobacillus brevis, Leuconostoc sp. i Enterococcus sp. Dominant lactococci strain was Lactococcus lactis ssp. lactis (35,85%) and for lactobacilli Lactobacillus paracasei ssp. paracasei (18,86%). Strains from genus Enterococcus sp. had the rate of 13,20%., U radu su izdvojeni i identifikovani izolati bakterija mlečne kiseline i enterokoka iz sjeničkog sira, proizvedenog na tradicionalan način, bez dodavanja starter kulture. Iz 10 uzoraka sjeničkog sira izdvojeno je 53 termofilna, mezofilna i citrat+ izolata na odgovarajućim selektivnim podlogama (MRS agar, M17 agar, LDCagar i LDV agar). Postupkom bojenja po Gramu, mikroskopskim pregledom i katalaza testom je utvrđeno da svi izolati predstavljaju čiste kulture Gram-pozitivnih i katalaza-negativnih bakterija pri čemu je utvrđeno da je 21 izolat štapićastog, a 35 okruglastog oblika. Radi razdvajanja enterokoka od laktokoka, za sve okruglaste forme je ispita-na sposobnost rasta pri 6,5% NaCI, pH 9,6 i nakon termičkog tretmana na 60°C 20 minuta je utvrđeno da od 35 izolata okruglastog oblika, 7 izolata podnosi navedene uslove. Determinacijom dobijenih izolata primenom API sistema i to za štapičaste oblike API CHL50testa, a za okruglaste oblike RAPID ID 32 Strep sistema, utvrđeno je da izolati pripadaju vrstama Lac-tococcus lactis ssp. lactis, Lactobacillus paracasei ssp. paracasei Lactobacillus plantarum, Lactococcus lactis ssp. lactis boiv. dicetylactis Lactobacillus curvatus, Lactobacillus brevis, Leuconostoc sp. i Enterococcus sp. Ubedljivo najveću zastupljenost je imala okruglasta vrsta Lactococcus lactis ssp. lactis (35,85%), a od štapićastih, vrsta Lactobacillus paracasei ssp. Paracasei (18,86%). Vrste roda Enterococcus sp. bile su zastupljene sa 13,20 %.

Published
2006

39. Lactic acid bacteria strains isolated from Sjenica cheese

Author

Radulović, Zorica, Radulović, Zorica, Martinović, Aleksandra, Radin, Dragoslava, Obradović, D., Radulović, Zorica, Radulović, Zorica, Martinović, Aleksandra, Radin, Dragoslava, and Obradović, D.

Abstract

Lactic acid bacteria strains isolated from autochthonous cheeses of Sjenica were investigated. In those products, where starters were not added fermentation occurred as a result of natural flora present in the surrounding environment. Forty thermophilic, mesophilic and citrat+ LAB strains were isolated by selective mediums (MRS agar, LM17 agar and LDC agar) from 5 samples of Sjenica-cheeses. They were exposed to further analysis and identification. After examination by Gram test and catalase test, 13 strains of LAB, were selected for further analysis. On the basis of lactose fermentation way and acid production in 1% reconstituted skimed milk, 6 strains were selected. Determination of these strains by API 50 CHL and Rapid ID 32 Strep tests showed that 2 strains belonged to the Lactococcus lactis ssp. lactis, 2 strains to the Lactococcus lactis ssp. cremoris and 2 strains to the Lactobacillus para.paracasei., U radu su izolovani i karakterisani sojevi bakterija mlečne kiseline izdvojeni iz sjeničkog sira, proizvedenog autohtonom tehnologijom, bez dodavanja starter kultura. Iz 5 uzoraka sjeničkog sira izvršena je izolacija 40 termofilnih, mezofilnih i citrat+ sojeva BMK na odgovarajućim selektivnim podlogama (MRS agar, LM17 agar i LDC agar). Ovi sojevi su dalje podvrgnuti ispitivanju na Gram reakciju i katalaza test, posle čega je izabrano 13 sojeva za dalja ispitivanja. Na osnovu načina fermentacije laktoze i acidogene sposonosti praćene u 1% rekonstituisanom obranom mleku selekcionisano je samo 6 sojeva. Determinacijom ovih sojeva pomoću API CHL 50 i Rapid ID 32 Strep testa, pokazalo se da 2 soja pripadaju vrsti Lactococcus lactis ssp. lactis, 2 soja Lactococcus lactis ssp. cremoris i 2 soja vrsti Lactobacillus para.paracasei.

Published
2004

42. Impact of the Population of Spoilage Microflora on the Growth of Listeria monocytogeneson Frankfurters

Author

Radin, Dragoslava, Niebuhr, Steven E., and Dickson, James S.

Abstract

Approximately 100 CFU/cm2of a five-strain mixture of Listeria monocytogeneswas coinoculated onto frankfurters with three different concentrations (102, 104, and 106CFU/cm2) of an undefined spoilage microflora derived from commercial frankfurters. The frankfurters were vacuum packaged and stored at 10°C for up to 48 days. The populations of L. monocyto-genes, aerobic mesophilic bacteria, lactic acid bacteria, and Enterobacteriaceaewere determined at various time intervals during storage. After 14 days, the population of L. monocytogeneswas highest when grown with a spoilage microflora population of 102CFU/cm2, and this trend continued until 48 days. Throughout the entire storage period, the populations of L. monocytogenesat any concentration of inoculated spoilage microflora rarely differed by more than 0.5 log CFU/cm2, and the maximum observed difference as 1.1 log CFU/cm2at 40 days. The growth rate of L. monocytogeneswas approximately the same at all concentrations of the inoculated spoilage microflora. These results suggest that the concentration of spoilage microflora present on the original processed meat may have a slight impact on the growth of L. monocytogenesin the package.

Published
2006
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43. Ekstrakt kore nara (Punica granatum L.) kao prirodni antivirusni agens za redukciju humanih norovirusa in vitro

Author

Živković, Ivana, Radin, Dragoslava D., Đekić, Ivana, Bigović, Dubravka, Radulović, Zorica, and Pantić, Milena

Subjects
humani norovirusi, medicinski biljni ekstrakti, ekstrakt kore nara, antinorovirusniefekat, komercijalni dezinficijensi, human noroviruses, medicinal plant extracts, pomegranate peel extract, antinoroviral effect, commercial disinfectants, human noroviruses, medicinal plant extracts, pomegranate peel extract, antinoroviraleffect, commercial disinfectants, humani norovirusi, medicinski biljni ekstrakti, ekstrakt kore nara, antinorovirusni efekat, komercijalni dezinficijensi
Abstract

Humani norovirusi (HuNoV) su dominatni uzročnici epidemija akutnog gastroenteritisa izazvanih kontaminiranom hranom. U cilju njihove redukcije sa površine svežeg povrća i površina koje dolaze u kontakt sa hranom, testirana je antinorovirusna aktivnost 11 ekstrakata lekovitih biljaka. Za dalja istraživanja izabran je ekstrakt kore nara, koji je u koncentraciji 5 mg/mL redukovao broj čestica HuNoV za 99% u fosfatnom puferu, simuliranim gastrointestinalnim fluidima i na površinama svežeg čeri paradajza i mladog luka, a za 91% u mleku. Matični sok od nara redukovao je HuNoV za 97%. Potencijal ekstrakta kore nara kao prirodnog dezinfekcionog sredstva na površinama od nerđajućeg čelika i plastike je značajan (> 3 log10 GE/μL) i u skladu sa predloženim normama koje se primenjuju za virusna dezinfekciona sredstva. Radi komparacije, testirano dezinfekciono sredstva na bazi hipohlorita (250 ppm) redukovalo je HuNoV na približno istom nivou. Proverena je dezinfekcija površina kontaminiranih mešavinom suspenzija HuNoV i koliformne bakterije Escherichia coli, primenom brzog ATP bioluminiscentnog testa i RT-qPCR metodom. Sredstvo na bazi hipohlorita bez naknadnog ispiranja, dalo je rezultat koji se našao u zoni upozorenja, dok su rezultati nakon ispiranja vodom detektovani u zoni čistog. Broj detektovanog HuNoV na nerđajućem čeliku i plastici, posle sanitacije sa sredstvom na bazi hipohlorita iznosio je 2,2 odnosno 2,38 log10 GE/μL. Takođe, pokušano je da se primenom alergen indikator protein testa detektuju različite koncentracije HuNoV (103- 106 GE/μL) nanete na prethodno sterilisanu površinu nerđajućeg čelika. Posle inkubacije na 70ºC/10 min, što povećava senzitivnost testa, najviša testirana koncentracija virusa dala je pozitivan rezultat. Human noroviruses (HuNoV) are the dominant agents of foodborne acute gastroenteritis and epidemic outbreaks. In order to reduce them from the surface of fresh vegetables and food-contact surfaces, the antinoroviral activity of 11 medicinal plant extracts was tested. For further research, pomegranate peel extract was selected, which at a concentration of 5 mg/mL reduced the number of HuNoV particles by 99% in phosphate buffer, simulated gastrointestinal fluids and on the surface of fresh cherry tomatoes and green onions, and by 91% in milk. Pomegranate juice reduced HuNoV by 97%. The potential of pomegranate peel extract as a natural disinfectant on stainless steel and plastic surfaces is significant (> 3 log10 GE/μL) and in accordance with the proposed standards applicable to viral disinfectants. For comparison, the tested hypochlorite-based disinfectant (250 ppm) reduced HuNoV to approximately the same level. Disinfection of surfaces contaminated with a mixture of suspension of HuNoV and coliform bacteria Escherichia coli was checked, using a rapid ATP bioluminescence test and RT-qPCR method. The hypochlorite-based agent without subsequent rinsing gave the result that was in the warning zone, while the results after rinsing with water were detected in the clean zone. The number of detected noroviruses on stainless steel and plastic, after sanitation with a hypochlorite-based agent was 2,2 and 2,38 log10 GE/μL, respectively. Also, an attempt was made to detect different concentrations of HuNoV (103-106 GE/μL) applied to a previously sterilized stainless steel surface using an allergen indicator protein test. After incubation at 70ºC/10 min which increases the sensitivity of the test, the highest tested virus concentration gave a positive result.

Published
2022

44. Uticaj mikrobioloških inokulanata na hranljivu vrednost i aerobnu stabilnost silaže kukuruza i senaže lucerke

Author

Ivetić, Aleksandra M., Grubić, Goran, Đorđević, Nenad, Radin, Dragoslava, Ružić-Muslić, Dragana, and Stojanović, Bojan

Subjects
aerobna stabilnost, inokulanti, senaža, lucerka, carbon dioxide, hranljiva vrednost, nutritive value, aerobic stability, siliranje, aerobna degradacija, haylage, inoculants, corn, ensiling, ugljen dioksid, kukuruz, silaža, aerobic deterioration, silage, alfalfa
Abstract

Sve silaže nezavisno od kvaliteta su podložne aerobnoj degradaciji. Izlaganje silaže vazduhu pri otvaranju silosa a zatim u i hranidbenom prostoru kada je najčešće na farmi sastavni deo TMR neizbežno dovodi do njenog aerobnog kvarenja. Aerobno kvarenje silaža je složen proces koji zavisi od mnogo faktora. Aerobna degradacija rezultira proizvodnjom CO2 i posledično gubicima. Zbog toga, koriste se inokulanti BMK koji mogu da efikasno usmere mlečno kiselinsku fermentaciju u željenom smeru i imaju uticaja na dužu aerobnu stabilnost silaže. Hemijski sastav i epifitna mikroflora isečene mase biljaka u momentu siliranja kao i vrsta primenjenog mikrobiološkog inokulanta utiču na promenu HV vrednosti i dužinu AS silaža. Ciljevi istraživanja bili su: 1. Određivanje razlika u HV, hemijskog i mikrobiološkog sastava između eksperimentalnih silaža 5 različitih hibrida (rani, 2 srednje rana, srednje kasni i 1 kasni) kukuruza siliranim sa tri različita mikrobiološka inokulanta i sa kontrolnim tretmanom tokom 60 dana; 2.Određivanje razlika u HV, hemijskog i mikrobiološkog sastava između eksperimentalnih senaža lucerke siliranim sa tri različita mikrobiološka inokulanta i sa kontrolnim tretmanom u periodu od 40, 90, 120 i 150 dana; 3.Određivanje uticaja 3 različita mikrobiološka inokulanta, kao i epifitne mikroflore u kontrolnom tretmanu na dužinu AS eksperimentalnih silaža kukuruza i senaže lucerke primenom laboratorijske metode Ashbell i Weinberg, (1991). U cilju ispitivanja uticaja mikrobioloških inokulanta na HV i AS silaže kukuruza korišćena su 3 različita inokulanta: inokulant 1 i 2 su sadržali različite heterofermentative i homofermentative BMK ; i inokulant 3 isključivo homofermentativnim BMK. Ukupan broj tretmana bio je 80. U cilju ispitivanja uticaja mikrobioloških inokulanta na HV i AS senaže lucerke korišćena su 3 različita inokulanta: inokulant 1 i 3 su sadržali različite isključivo homofermentativne BMK; i inokulant 2 koji je sadržao heterofermentativne i homofermentativne BMK. Ukupan broj tretmana bio je 64...

Published
2017

45. Bakteriofagi kao agensi u kontroli formiranja biofilmova Pseudomonas aeruginosa

Author

Vujović, Bojana A., Radin, Dragoslava, Raičević, Vera, Teodorović, Smilja, Nikšić, Miomir, and Knežević, Petar

Subjects
P. aeruginosa, bacteriophages, fenotipske karakteristike, genetski diverzitet, bakteriofagi, genetic diversity, phenotype characteristics, biofilm, MLST
Abstract

Pseudomonas aeruginosa je štapićasta, asporogena bakterija, široko rasprostranjena u sredinama kao što su zemljište, voda, ljudski i životinjski organizmi, biljke i otpad. P. aeruginosa poseduje jedan cirkularni hromozom koji je smešten u citoplazmi ćelije, kao i više plazmida značajnih za patogena svojstva ove bakterije. Genom P. aeruginosa je veličine 5,2 do 7,1 Mbp, u kome je ukupna zastupljenost guanina i citozina oko 65%. Najveći broj genetskih i genomskih analiza P. aeruginosa je usmeren ka kliničkim izolatima, dok je mnogo manja pažnja posvećena izolatima iz životne sredine, zbog čega je manje od 10% genomskih sekvenci deponovanih u Nacionalnom Centru za Biotehnološke Informcije (NCBI) izolata poreklom iz životne sredine. Jedna od glavnih kompetitivnih prednosti P. aeruginosa u preživljavanju u različitim uslovima spoljašnje sredine je sposobnost formiranja biofilmova, a brojna istraživanja su pokazala da većina izolata ima ovu sposobnost. Izučavanju biofilmova se u poslednje vreme poklanja značajnija pažnja u oblastima mikrobiologije hrane, vode, životne sredine kao i medicinske mikrobiologije. Prisustvo biofilmova u životnom okruženju čoveka, različitim sistemima za transport industrijske, površinske vode, vode za navodnjavanje kao i medicinskoj opremi i pomagalima, čine biofilmove aktuelnom temom u medicini, farmaciji, ali i u kontekstu higijene hrane. Eliminacija bakterijskih biofilmova je izuzetno težak proces, zbog toga postoji potreba da se razvijaju altenativni načini za sprečavanje formiranja i kontrolu biofilmova. Polazeći od napred navednog, osnovni naučni cilj ove doktorske disertacije je sagledavanje mogućnosti primene bakteriofaga u kontroli formiranja biofilmova, kao i uticaja na već formirane biofilmove sojeva vrste Pseudomonas aeruginosa, pri definisanim ekološkim uslovima u pogledu temperature, pH i koncentracije NaCl. Iz uzoraka sedimenta, aktivnog mulja, površinske vode, vode za piće i zemljišta sa različitih lokaliteta izolovano je 30 izolata Pseudomonas aeruginosa. Molekularna identifikacija i tipizacija 30 izolata Pseudomonas je izvršena modifikovanom MLST šemom za P. aeruginosa (http://pubmLst.org/paeruginosa/) pomoću pet housekeeping gena: acsA, guaA, mutL, ppsA i trpE. Za filogenetske analize je korišćen programski paket MEGA, verzija 8... Psudomonas aeruginosa is rod shape, asporogenous bacteria, wide spread in soil, water, human and animal organisms, plants and solid wastes. P. aeruginosa has one circular chromosome which is placed into the cell’s cytoplasm, as well as more plasmids which are significant for pathogen characteristics of this bacterium. Genome size of P. aeruginosa is from 5.2 to 7.1 Mbp and Guanine and Cytosine content in the genome is approximately 65 %. The number of the genetic and genome’s analyses of P. aeruginosa is directed to the clinical isolates and significantly lower attention is devoted to the isolates from environment. The consequence is that the less than 10 % of the genome’s sequences deposited in the National Centre for Biotechnology Information (NCBI) in USA are with environmental origin. One of the main competitive advantages of P. aeruginosa survival under different environmental conditions is biofilm forming ability. Numerous investigations are shown that main part of isolates have this ability. Researches of the biofilm are paying great attention in last decades, especially in the following fields: microbiology of food, water, environment, as well as medical microbiology. Because of biofilm presence in the human environment, different facilities for water transport in industry, surface waters, water for irrigation purposes, medical equipment and tools, biofilm became very important goal for investigation in medicine, pharmacy and food hygiene. Elimination of the bacteria’s biofilms is extremely hard process and because that, alternative methods for avoiding biofilm formation, as well as biofilm control are very necessary. Taking in mind all these previously mentioned facts, investigation of Pseudomonas aeruginosa strains diversity selected from environment and its biofilm forming ability and forming of the identified bacteria strains collection is established as main scientific goal of this Ph.D. thesis. The goal of this Ph.D. thesis is investigations of possibility of influence, forming and removal of created biofilms by specific bacteriophages acting in in-vivo conditions and forming of phages collection...

Published
2016

46. Ispitivanje antimikrobnih osobina hitozana na rast Listeria monocytogenes u povrću

Author

Jovanović, Gordana D., Klaus, Anita, Nikšić, Miomir, Radin, Dragoslava, Zlatković, Branislav, and Katić, Vera

Subjects
omotači i filmovi hitozana, antimicrobial properties of chitosan, minimalno prerađeno povrće, etarska ulja, chitosan coatings and films, antimikrobna svojstva hitozana, minimally processed vegetables, Listeria monocytogenes, essential oils
Abstract

Zadatak ove doktorske disertacije bio je da se utvrdi antimikrobna aktivnost hitozana u formi omotača i filmova na sojeve Listeria monocytogenes ATCC 19112 i Listeria monocytogenes ATCC19115 u sveže sečenom, minimalno prerađenom povrću. Antimikrobna svojstva hitozana analizirana su u različitim vrstama hrane kao što su sveže sečeno povrće: kupus, šargarepa i crna rotkva ali i majonez, koji se često koristi za pripremu salata sa povrćem. Osim antimikrobne aktivnosti hitozana, ispitivan je uticaj filmova hitozana na promenu pH vrednosti, sadržaj rastvorljive suve materije i senzorne karakteristike ispitivanog povrća. U cilju realizacije postavljenih zadataka izrađeni su različiti modeli omotača i filmova sa hitozanom. Omotači hitozana su pripremljeni sa mlečnom ili sirćetnom kiselinom tako da je ukupna koncentracija hitozana u njima iznosila 0,25%; 0,5% ili 1%. Filmovi hitozana su pripremljeni sa dodatkom želatina tako da je u njima postignuta konačna koncentracija od 0,5%; 1% i 2% hitozana. U cilju poboljšanja antimikrobne aktivnosti u filmove je dodato etarsko ulje mente ili timijana u koncentraciji od 0,1% i 0,2%. Odabir ovih ulja izvršen je na osnovu rezultata ispitivanja antimikrobne aktivnosti etarskih ulja koja su pokazala da etarska ulja timijana i mente imaju najefikasnije dejstvo na testirane bakterijske sojeve. Analizom dobijenih rezultata utvrđeno je da testirani sojevi bakterija imaju različitu sposobnost preživljavanja na ispitivanim vrstama povrća. Najveća inhibicija rasta ispitivanih bakterijskih sojeva postignuta je kod crne rotkve i šargarepe. Sam kupus ne ispoljava inhibitorni efekat na rast ispitivanih bakterija, već značajno doprinosi razvoju ovih bakterija. Antimikrobna aktivnost omotača hitozana zavisi od upotrebljene koncentracije hitozana, vrste organske kiseline koja je upotrebljena kao rastvarač, kao i od vrste povrća u kome se omotači primenjuju. Najizraženija inhibicija bakterijskih sojeva postignuta je u crnoj rotkvi i šargarepi, sa 1% omotačima hitozana koji su pripremljeni sa sirćetnom kiselinom... The objective of this doctoral thesis was to determine the antimicrobial activity of chitosan in the form of coatings and films against the strains of Listeria monocytogenes ATCC 19112 and Listeria monocytogenes ATCC 19115 in fresh-cut, minimally processed vegetables. The antimicrobial properties of chitosan were analyzed in different types of food such as fresh cut vegetables: cabbage, carrot and black radish and mayonnaise, which is often used to prepare the salad with vegetables. In addition to the antimicrobial activity of chitosan, the influence of chitosan films on pH changes, content of soluble solids and sensory properties of tested vegetables, have been investigated. In order to realize of given tasks, different coatings and films with the chitosan were made. Chitosan coatings were prepared with lactic or acetic acid, so that the total concentrations of chitosan coatings have been 0.25%; 0.5% or 1%. Films of chitosan were prepared with the addition of gelatin and final concentrations of chitosan have been 0.5%; 1% and 2%. In order to improve the antimicrobial activity of the films, essential oil of mint or thyme in a concentration of 0.1% and 0.2% were added. The choice of these oils was made on the basis of the antimicrobial activity of thyme and mint essential oils which have been shown as the most effective against the tested bacterial strains. The analysis of the results showed that the tested strains of bacteria have different viability in the tested types of vegetables. The highest growth inhibition of tested bacterial strains was achieved in the black radish and carrots. Cabbage alone does not exhibit an inhibitory effect on growth of the bacteria, but also significantly contributes to the development of these bacteria. Antimicrobial activity of chitosan coatings depends on the concentration of chitosan used, type of organic acid which is used as a solvent, and the type of vegetable in which the coatings were applied. The highest inhibition of growth of bacterial strains was obtained with black radish and carrot, with 1% of chitosan coatings, which have been prepared with acetic acid...

Published
2016

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