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Namen dela je bil ugotoviti znanje s področja dobre higienske prakse (DHP) pri zaposlenih (58) v izbranem živilskem obratu. Za zaposlene smo s področja DHP izvedli tudi izobraževanje. Znanje smo ocenili z anketo, ki smo jo izvedli pred izobraževanjem in po njem. Vrednotili smo pravilne odgovore. Rezultati kažejo, da je delež pravilnih odgovorov bistveno (p ≤ 0,001) večji po izobraževanju. Stopnja znanja anketirancev pred izvedenim izobraževanjem je bila 62,3 ± 25,9 % pravilnih odgovorov, po njem pa je odstotek pravilnih odgovorov znašal 91,0 ± 6,6 %. Ugotovili smo, da so anketiranci, ki so se v preteklosti že udeležili izobraževanja (86,2 %) s področja DHP, dosegli bistveno boljši (p ≤ 0,001) rezultat (68,4 % pravilnih odgovorov pred izobraževanjem in 92,2 % pravilnih odgovorov po izobraževanju), kot anketiranci, ki se še nikoli niso udeležili izobraževanja (13,8 %) (45,9 % pravilnih odgovorov pred izobraževanjem in 82,3 % pravilnih odgovorov po izobraževanju). Pomemben vpliv so pokazale delovne izkušnje (p ≤ 0,001), saj so največ znanja pokazali zaposleni z več kot 15 let delovnih izkušenj. Velik vpliv (p ≤ 0,001) ima tudi pridobljeno izobraževanje anketirancev, saj so tisti, ki imajo končano vsaj poklicno izobraževanje s področja živilstva, najboljše znanje s področja DHP. Pozitiven učinek izobraževanja se je pokazal tudi na spremembi mnenj anketirancev po usposabljanju, ker se je zmanjšal delež anketirancev, ki jim je bila udeležba na usposabljanjih v breme, povečal pa se je delež oseb, ki so menile, da je usposabljanje koristno za njihovo delo, pridobljeno znanje pa lahko uporabijo pri svojem delu. The aim of work was to determine the level of knowledge in field of good hygiene practice (GHP) among employees (58) in selected food plant. We also conducted training sessions for employees in the area of GHP. Knowledge was determined using a survey before and after the training. We evaluated the correct responses. The results showed that the percentage of correct answers was significantly higher (P ≤ 0.001) after the training. The knowledge level before training was 62.3 ± 25.9 % of correct answers, and after it the percentage of correct answers was 91.0 ± 6.6 %. It was found that the respondents who had participated in GHP training in the past (86.2 %) had significantly better (P ≤ 0.001) result (68.4 % correct answers before training and 92.2 % correct answers after training) than respondents who had never participated in training (13.8 %) (45.9 % correct answers before training and 82.3 % correct answers after training). Work experience showed a significant effect (P ≤ 0.001), as employees with more than 15 years of work experience showed the most knowledge in food industry. Respondents' acquired education also has a significant effect (P ≤ 0.001), as those who received training in food science had the best knowledge of GHP. The positive effect of the training was also reflected in the change of respondents' opinions after the training as burden decreased, while the percentage of people who perceived the training was useful in their work increased and they can use the knowledge in their work.

Uporaba fungicidov za zatiranje plesni, ki povzročajo kvar sadja in zelenjave, je vse bolj omejena. Vzroki so v dolgoletni preobsežni uporabi fitofarmacevtskih sredstev (FFS), razvoju novih sevov plesni, ki so prilagojeni ali celo odporni proti fungicidom ter v potencialno škodljivih vplivih ostankov pesticidov na zdravje ljudi. Zato so pomembne alternativne metode in ena od njih je uporaba modre LED-svetlobe, katere osnovni mehanizem temelji na fotodinamični inaktivaciji (PDI). Namen diplomskega dela je pojasniti fotodinamični vpliv modre LED-svetlobe in možnosti uporabe v praksi za zaviranje kvara sadja in zelenjave, ki ga povzročajo plesni. Pregled strokovne literature o uporabi modre LED-svetlobe na plodovih sadja in zelenjave med skladiščenjem je pokazal spodbudne rezultate. Pri obsevanju plesni na/v živilu z modro LED-svetlobo se tvorijo reaktivni kisikovi radikali (ROS), ki povzročijo poškodbe različnih celičnih sestavin kot so lipidi, proteini in nukleinske kisline, ki lahko vodijo do inhibicije rasti ali celo celične smrti in propada plesni. Modra LED-svetloba lahko vpliva tudi na samo kakovost živil, npr. sprememba barve plodov, povečanje vsebnosti nekaterih antioksidantov, kot so fenolne spojine, antocianini, upočasni se gnitje in staranje pridelkov ter poveča odpornost plodov proti boleznim, povzročenim s strani plesni. Uporaba modre LED-svetlobe predstavlja okolju prijaznejšo metodo v primerjavi z uporabo fungicidov in bi jo lahko komplementarno povezovali z drugimi metodami za zaščito in podaljšanje trajnosti sadja in zelenjave. Ker na učinkovitost modre LED- svetlobe vpliva veliko dejavnikov, bo za njeno uporabo v praksi potrebnih še veliko raziskav. The use of fungicides to control molds that cause spoilage of fruits and vegetables is increasingly limited. Mainly due to their excessive use in past, the development of new resistant mould strains and because of potentially harmful effects of pesticide residues to human health. Alternative methods are therefore increasingly important. One of them is irradiation of fruits and vegetables with blue LED light or photodynamic inactivation (PDI) with blue LED light. Researchers have demonstrated the antimicrobial effect of blue LED light mainly as antibacterial treatment and less frequently as antifungal treatment. The purpose of this work is to explain photodynamic effect of blue LED light irradiation and possibilities of its practical application as antifungal method used to prevent fruit and vegetable spoilage. The results have showed potential of blue LED light irradiation as it can inactivate mould by producing reactive oxygen species (ROS) that cause damage to different cellular components such as lipids, proteins and nucleic acids. These effects can lead to growth inhibition or even moulds destruction. Blue LED light might also affect quality of fruit and vegetables such as colour, increasing content of certain antioxidants, such as phenolic compounds, anthocyanins, slows rot and aging of fruits and vegetables and increase their resistance to mold-borne diseases. The use of blue LED light is a more environmentally friendly method compared to the use of fungicides and could be use as complementary strategies to protect fruit and vegetables from mould spoilage. As the efficiency of blue LED light is influenced by many factors, its application still requires many scientific research.

Plesni vrste Penicillium expansum povzročajo gnilobo številnih živil, med katerimi so te plesni najpogostejši kontaminanti jabolk. Ker plesni vrste P. expansum lahko tvorijo patulin, predstavljajo tudi tveganje za varnost živil. Glavni namen dela je bil določiti sposobnost njihove adhezije, saj večina strokovne literature opisuje bakterijsko adhezijo, medtem ko so raziskave adhezije plesni redke. V prvem delu smo metodo določanja adhezije z barvilom kristal vijolično (KV) optimizirali z izbiro gojišča (sladni agar in krompirjev agar) in starosti konidijev (7 in 10 dni) za pripravo inokuluma ter določitvijo valovne dolžine (570 nm in 584 nm) za kvantifikacijo adheriranih plesni. V drugem delu smo proučevali adhezijo plesni vrste P. expansum tako, da smo preverili vplive izbranih intrinzičnih in ekstrinzičnih dejavnikov. Rezultati so pokazali, da je za spremljanje adhezije boljše, ča uporabimo inokulum pripravljen iz 10 dni stare kulture, saj je bila adhezija tu veliko večja ter da gojišče, na katerem rastejo plesni za pripravo inokuluma, ne vpliva na adhezijo. Pri primerjavi rezultatov dobljenih z meritvami absorbanc sproščenega KV pri različnih valovnih dolžinah, razlik nismo zaznali. Med intrinzičnimi dejavniki smo ugotovili, da ima velik vpliv na adhezijo začetno število konidijev, saj je bila adhezija največja pri 108 K/ml (K: konidiji), ter čas adhezije plesni vrste P. expansum (adhezija po 20 urah je bila večja kot po 40 urah), medtem ko vrsta seva (tipski sev P. expansum ŽMJ 497, divji sev P. expansum ŽMJ 464) ni bistveno vplivala na adhezijo. Plesni vrste P. expansum dobro rastejo na številnih materialih, ki se uporabljajo tudi v živilski industriji, zato smo primerjali njihovo adhezijo na različnih površinah (polistiren, polipropilen, polietilen visoke gostote, polietilen tereftalat, steklo in nerjaveče jeklo). Največjo adhezijo smo določili na površini polistirena. Adhezijo plesni vrste P. expansum na vseh površinah smo opazovali tudi z vrstično elektronsko mikroskopijo in ugotovili, da so morfološke lastnosti povezane z vrsto površine. Zaključimo lahko, da je metoda barvanja s KV primerna kot preliminarna metoda določanja adhezije plesni in da se plesni vrste P. expansum dobro adherirajo na površino, vendar so potrebne nadaljnje raziskave. Strains of Penicillium expansum cause rotting of many foods, among which they are the most common contaminant of apples. As P. expansum can form patulin it is also a food safety risk. The main purpose was to determine P. expansum adhesion ability, since most scientific literature describes bacterial adhesion, while moulds adhesion is rare. In the first part, the method of determining adhesion with crystal violet dye (CV) was optimized by choosing medium (malt agar and potato agar) and age of conidia (7 and 10 days) for preparation of inoculum and determining the wavelength (570 nm and 584 nm) for adherence quantification. In the second part, we studied the adhesion of P. expansum by checking the influence of selected intrinsic and extrinsic factors. Results showed that for adhesion monitoring it is better to use an inoculum prepared from a 10-day-old culture, as the adhesion was much greater, and that the culture medium on which the moulds grow prior inoculum preparation, does not affect adhesion. When comparing the results obtained by measuring the absorbance of released CV at different wavelengths no differences were found. Among the intrinsic factors, we found out that initial number of conidia had a major influence since adhesion was highest at 108 K/ml (K: conidia), and adhesion time (adhesion after 20 h was greater than after 40 h), while strain (P. expansum ŽMJ 497 type strain, P. expansum ŽMJ 464 wild strain) did not affect adhesion. P. expansum strains grow well on many materials that are also used in food industry and we compared adhesion on different surfaces (polystyrene, polypropylene, high-density polyethylene, polyethylene terephthalate, glass and stainless steel). The maximum adhesion was determined on the polystyrene. Adhesion of P. expansum on surfaces was also observed by scanning electron microscopy and it was found that the morphological properties are related to the type of surface. We can conclude that the KV staining method is suitable as a preliminary method for determining mould adhesion and that P. expansum adhere well to the surface, but further research is needed.

Mikroalge so zaradi sposobnosti proizvajanja širokega spektra organskih spojin, med katerimi imajo številne bioaktivne lastnosti, vse bolj proučevane na različnih znanstvenih področjih. Med temi spojinami so še posebej zanimive tiste s protimikrobnim in protiadhezivnim delovanjem. V raziskavi smo proučevali bioaktivne lastnosti mikroalg vrst Arthrospira platensis in Chlorella vulgaris pri bakterijah vrst Escherichia coli, Pseudomonas aeruginosa ter Staphylococcus aureus in kvasovkah vrste Candida albicans. Določali smo protimikrobno delovanje z metodo razredčevanja v mikrotitrski plošči, s katero smo izbranim ekstraktom mikroalg določili minimalno inhibitorno koncentracijo (MIK) ter protiadhezivno delovanje z metodo barvanja s kristal vijoličnim, za kar smo uporabili subinhibitorno koncentracijo (0,1 MIK), saj nismo želeli vpliva ekstraktov na rast, temveč samo na adhezijo. Rezultati protimikrobnega delovanja so pokazali, da sta učinkovita ekstrakta CMAS in CMAC (CMA: ekstrakcija z mešanico kloroform, metanol, aceton S: A. platensis C: C. vulgaris) pri bakterijah vrste S. aureus (MIK = 10 mg/ml), medtem ko ostali ekstrakti niso imeli protimikrobnega učinka pri izbranih mikroorganizmih (MIK > 20 mg/ml). V nadaljevanju raziskave smo ugotovili, da protiadhezivno deluje ekstrakt MC (M: ekstrakcija z metanolom C: C. vulgaris) pri bakterijah vrste S. aureus (28,8 % inhibicija), medtem ko je ekstrakt CMAS povečal adhezijo bakterij vrste S. aureus, in ekstrakt MS bakterijam vrst S. aureus in P. aeruginosa. Slednje bi lahko pripisali napaki pri meritvi absorpcije, do katere je prišlo zaradi temne obarvanosti obeh ekstraktov. Rezultati naše raziskave kažejo, da mikroalge vrst A. platensis in C. vulgaris predstavljajo velik potencial v razvoju novih in učinkovitih bioaktivnih sredstev, vendar so potrebne dodatne raziskave. Microalgae are becoming increasingly popular in various scientific fields due to their ability to produce a wide range of organic compounds, among which many have bioactive properties. Among the mentioned compounds, those with antimicrobial and anti-adherence activities are particularly interesting. Such microalgae also include Arthrospira platensis and Chlorella vulgaris, whose bioactive properties against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans strains were researched in our study. We determined antimicrobial activity with minimum inhibitory concentration (MIC) of microalgae extracts with the broth microdilution method. We also determined antiadhesive activity with crystal violet staining method, for which we used sub-inhibitory concentration (0.1 MIC) of microalgae extracts, as we did not want to influence the growth but only adhesion of selected microorganisms. The results of antimicrobial activity showed that only CMAS and CMAC extracts (CMA: extraction with mixture of chloroform, methanol, acetone S: A. platensis C: C. vulgaris) were effective against S. aureus (MIC = 10 mg/ml), while other extracts had no antimicrobial effect against selected microorganisms (MIC > 20 mg/ml). In the continuation of our study, we found that MC extract had an antiadhesive effect against S. aureus (28.8% inhibition), while CMAS extract increased adhesion of S. aureus and MS extract increased adhesion of P. aeruginosa and S. aureus. This could be attributed to an error in absorbance measurement due to dark coloration of both extracts. Results of our research, together with results of researches of other authors proved that A. platensis and C. vulgaris microalgae represent a great potential in development of new and effective bioactive agents, but further researches are needed.

Mikroalge proizvajajo zunaj- in znotrajcelične presnovke z različnimi biološkimi aktivnostmi, kot so protibakterijske in protiadhezivne lastnosti, zato so zanimive na različnih področjih, vključno pri preprečevanju obolenj v ustni votlini. Namen magistrskega dela je bil ugotoviti protibakterijske in protiadhezivne lastnosti ekstraktov mikroalg vrst Arthrospira platensis in Chlorella vulgaris z bakterijami vrst Streptococcus cristatus in Staphylococcus warner, ki so bile izolirane iz ustne votline. Minimalno inhibitorno koncentracijo (MIC) ekstraktov mikroalg MC, MS, CMAC in CMAS (M: ekstrakcija z metanolom CMA: ekstrakcija z mešanico kloroforma, metanola in acetona C: C. vulgaris S.: A. platensis) smo določili z metodo razredčevanja v mikrotitrski ploščici. Za proučevanje bakterijske adhezije smo uporabili 0,1 MIC ekstraktov mikroalg. Protiadhezivne lastnosti ekstraktov smo določili najprej na polistirenski površini z metodo barvanja z barvilom kristal vijolično in v nadaljevanju na zobni površini z metodo štetja kolonij na trdnem gojišču. Rezultati so pokazali, da ima najboljšo protibakterijsko aktivnosti ekstrakt CMAS (MIC 10 mg/L). Pri subinhibitorni koncentraciji 0,1 MIC je protiadhezivno aktivnost imel ekstrakt CMAS pri bakterijah vrste Strep. cristatus, saj je bila adhezija na polistiren zmanjšana za 84 %, in pri bakterijah vrste Staph. warneri, kjer je bila adhezija zmanjšana za 36 %. Tudi na zobni površini je ekstrakt CMAS inhibiral adhezijo bakterij vrste Staph. warneri, medtem ko ni vplival na adhezijo bakterij vrste Strep. cristatus. Rezultati eksperimentalnega dela potrjujejo kompleksnost proučevanja bioaktivnih lastnosti naravnih ekstraktov, ki je odvisna od mnogih dejavnikov. Protibakterijska in protiadhezivna aktivnost ekstrakta je odvisna ne samo od vrste ekstrakta, ampak tudi od postopka ekstrakcije, vrste uporabljenega topila ter od postopka testiranja bioaktivnih lastnosti (npr. izbira topila, v katerem so ekstrakti raztopljeni, izbira bakterij, izbira površine, izbira metode) in od vrste uporabljenih mikroorganizmov. Dobljeni rezultati kažejo na protiadhezivne lastnosti ekstraktov mikroalg vrst A. platensis in C. vulgaris in nakazujejo možnosti njihove uporabe tudi na področju ustne higiene. Microalgae produce extracellular and intracellular metabolites with various biological activities, such as antibacterial and antiadhesive properties making them very interesting in various fields, including prevention of oral disease. The aim of the master thesis was to determine antibacterial and antiadhesive properties of Arthrospira platensis and Chlorella vulgaris microalgae extracts on Streptococcus cristatus and Staphylococcus warneri strains, isolated from oral cavity. Minimal inhibitory concentration (MIC) of MC, MS, CMAC and CMAS microalgae extracts (M: methanol extraction CMA: extraction with mixture of chloroform, methanol and acetone C: C. vulgaris S: A. platensis) was determined by the microdilution method. To study bacterial adhesion, we use 0,1 MIC of microalgal extracts. The antiadhesive properties of the extracts were determined first on polysryrene surface by crystal violet staining method and then on dental surface by colony count method. The results showed that CMAS extract had the best antibacterial activity (MIC 10 mg/mL). At a subinhibitory concentration of 0.1 MIC, CMAS extract had antiadhesive activity against Strep. cristatus, as adhesion to polystyrene was reduced for 84 %, while adhesion of Staph. warneri was reduced for 36 %. On the dental surface, CMAS extract inhibited the adhesion of Staph. warneri, while it had no effect on adhesion of Strep. cristatus. The results of the experimental work confirm the complexity of studying the bioactive properties of natural extracts, which depends on many factors. The results show that the antibacterial and anti-adhesive activity of the microalgal extract depend on the extraction process, the type of solvent used, and the procedure used to test the bioactive properties (e.g. choice of the solvent in which the extracts are dissolved, choice of bacteria, choice of the surface, choice of the method) and type of microorganisms used. Obtained results show the antiadhesive properties of A. platensis and C. vulgaris microalgae extracts and suggest their possible application in field of oral hygiene

Uživanje jabolk ima veliko pozitivnih učinkov na zdravje ljudi. Z visoko vsebnostjo antioksidantov jabolka zmanjšujejo tveganje za pojav različnih bolezni. Zanimalo nas je, ali svetloba izbranih valovnih dolžin (420 nm, 450 nm) med 18 dnevnim skladiščenjem pri 10 °C pripomore k povečani tvorbi flavonoidov ter večjemu antioksidativnemu potencialu (AOP) jabolk (Malus domestica) sorte Angold ter če ima spremenjena vsebnost fenolnih spojin vpliv na protibakterijsko aktivnost ter na adhezijo bakterij vrste L. monocytogenes na jabolko. Ugotovili smo, da sta imela ekstrakta jabolčnih lupin, ki sta bila 18 dni skladiščena pri 420 nm in 450 nm (E420 in E450) manjšo vsebnost flavonoidov kot ekstrakt jabolčnih lupin svežih jabolk (E0) in ekstrakt jabolčnih lupin jabolk, ki so bila 18 dni skladiščena v temi (Et). Vrednosti AOP ekstraktov jabolčnih lupin se niso razlikovale glede na valovno dolžino svetlobe. Protibakterijska aktivnost proti bakterijam vrste L. monocytogenes je bila boljša pri ekstraktih jabolčnih lupin E420 in E450 kot pri ekstraktih E0 in Et. Iz tega lahko sklepamo, da obsevanje jabolk z modro svetlobo vpliva na večjo vsebnost bioaktivnih spojin, ki pa niso flavonoidi. Adhezija bakterij vrste L. monocytogenes na jabolkih se je zmanjšala po 48-urni in 72-urni inkubaciji pri svežih jabolkih, jabolkih, ki so bila 18 dni skladiščena pri 420 nm in jabolkih, ki so bila 18 dni skladiščena pri 450 nm. Pri jabolkih, ki so bila 18 dni skladiščena v temi, smo zmanjšanje adhezije zaznali po 72-urni inkubaciji. Zaključimo lahko, da modra svetloba uporabljena med skladiščenjem jabolk, vpliva na povečanje bioaktivnega potenciala jabolk, vendar bi bile potrebne nadaljnje raziskave. Eating apples has many positive effects on human health. Due to a high content of antioxidants apples reduce the risk of various deseases. We were investigating whether irradiation of apples with blue lights of selected wavelengths (420 nm and 450 nm) during 18 days of storage at 10 °C contributed to an increased flavonoid content and increased antioxidant potential (AOP) of apples (Malus domestica) cv. Angold and if altered content of phenolic compounds affects antibacterial activity against L. monocytogenes and the ability of L. monocytogenes to adhere to the apple. Apple peel extracts made from apples stored at 420 nm and 450 nm (E420 and E450) for 18 days had lower flavonoid content than fresh apple peel extract (E0) and apple peel extract stored for 18 days in the dark (Et). The AOP values of the apple peel extracts did not differ between wavelengths. E420 and E450 apple peel extracts were more efficient against L. monocytogenes than E0 and Et apple peel extracts. From these results we can conclude that irradiation of apples with blue light increased the content of bioactive compounds other than flavonoids. Decreased adhesion of L. monocytogenes on apples was detected after 48-hour and 72-hour incubation of fresh apples, apples stored for 18 days at 420 nm and apples stored for 18 days at 450 nm. In apples stored for 18 days in the dark, however, a decrease in adhesion was observed after 72-hours of incubation. We can conclude that blue light applied during apples storage increases the bioactive potential of apples, but further investigations are needed.

V diplomskem delu smo proučevali primerljivost alternativne metode za določanje kvasovk in plesni (SimPlate Y&M CI) s klasično metodo za kvantifikacijo kvasovk in plesni na gojišču DRBC (gojišče z barvilom dikloran rdeče in bengal ter kloramfenikolom). Alternativna metoda, ki je od klasične hitrejša ter enostavnejša, bi lahko na področju živilstva zelo pripomogla k pravočasnemu odkrivanju kvarljivcev živil. Mikrobiološko preiskavo smo izvedli z naravno kontaminiranim vzorcem zgornjesavinjskega želodca ter umetno kontaminiranim vzorcem zgornjesavinjskega želodca, ki smo mu dodali kvasovke vrste Saccharomyces cerevisiae v koncentraciji 108 CFU/ml. Po podaljšani inkubaciji (8 dni) alternativna in klasična metoda kvantifikacije kvasovk in plesni v živilu nista dali primerljivih rezultatov. Možen in najbolj verjeten vzrok so bile spremembe dehidriranega gojišča SimPlate. Nadaljnje raziskave z metodo SimPlate Y&M CI za določanje kvasovk in plesni v živilu bi vključevale izvedbo mikrobioloških preiskav z več različnimi živili (npr. surova živila, izdelki tekoča poltrdna in trdna živila) in z različnimi mikroorganizmi (npr. različne vrste kvasovk, plesni, mešane kulture, ki bi bile naravno prisotne in dodane v majhnem ter velikem številu) in več ponovitvami. The aim of thesis was to determine the comparability of an alternative method for the quantification of yeasts and molds (SimPlate Y&M CI) with the traditional method for quantification of yeasts and molds on DRBC agar (dichloran rose-bengal chloramphenicol agar). SimPlate Y&M CI as an alternative method is faster and simpler than the traditional method and therefore could contribute significantly to faster detection of spoilage yeasts and molds in food. Microbiological tests were performed on a naturally contaminated sample of Zgornjesavinjski želodec and an artificially contaminated sample of Zgornjesavinjski želodec to which Saccharomyces cerevisiae was added at a concentration of 108 CFU/ml. After a prolonged incubation of 7 days, the alternative and traditional methods did not give comparable results. The possible and most probable cause for the results obtained is changes in the dehydrated SimPlate medium. Further investigation of the SimPlate Y&M CI method for the quantification of yeasts and molds in foods should include microbiological tests on several different foods (e.g. raw foods, food products, liquid, semi-solid and solid foods) and with different microorganisms (different yeasts, different molds or mixed cultures naturally present and added at lower and higher concentrations) and several replicates.

Namen diplomske naloge je bil ovrednotiti protibakterijsko delovanje eteričnega olja in hidrolata cimeta (Cinnamomum zeylanicum) proti bakterijam vrst Escherichia coli, Staphylococcus aureus, Listeria innocua in Pseudomonas aeruginosa. Protibakterijsko delovanje eteričnega olja smo preverjali z metodo razredčevanja v mikrotitrski ploščici, protibakterijsko delovanje hidrolata pa z metodo razredčevanja v mikrotitrski ploščici in z metodo difuzije. Minimalno inhibitorno koncentracijo (MIC) smo določili in potrdili tudi z metodo štetja kolonij na trdnem gojišču. Za bakterije vrste E. coli smo določili, da je vrednost MIC 0,78 mg/ml, za S. aureus 0,2 mg/ml, za L. innocua od 0,1 do 0,2 mg/ml in za P. aeruginosa 1,56 mg/ml. Najboljšo protibakterijsko aktivnost smo tako določili za bakterije vrste L. innocua, ki je imela najnižjo vrednost MIC. Hidrolat cimeta ni imel protibakterijske aktivnosti, ne glede na različne uporabljene metode. Z eksperimentalnim delom smo pokazali, da ima eterično olje cimeta protibakterijske lastnosti in da ima večji učinek na grampozitivne (S. aureus in L. innocua) kot na gramnegativne (E. coli, P. aeruginosa) bakterije. Rezultati kažejo na to, da bi lahko podrobnejše raziskave o aktivnosti eteričnega olja na bakterije vodile do uporabe eteričnega olja cimeta kot naravnega protimikrobnega sredstva v živilstvu. The purpose of the research was to determine the antibacterial effects of the cinnamon (Cinnamomum zeylanicum) essential oil and hydrolate against Escherichia coli, Staphylococcus aureus, Listeria innocua and Pseudomonas aeruginosa. The antibacterial activity of the essential oil was determined by broth microdilution method. The antibacterial action of the hydrolate was determined by the broth microdilution method and by agar diffusion method. The minimal inhibitory concentration (MIC) was determined and confirmed by plate count method. For E. coli, the MIC value was 0.78 mg/ml, for S. aureus 0.2 mg/ml, for L. innocua from 0.1 to 0.2 mg/ml and for P aeruginosa 1.56 mg/ml. The best antibacterial activity was showed for L. innocua, which had the lowest MIC value. Cinnamon hydrolate showed no antibacterial activity irrespective used methodology. The results of experimental work showed that cinnamon essential oil has antibacterial properties and has a greater effect on gram-positive (S. aureus and L. innocua) then on gram-negative (E. coli, P. aeruginosa) bacteria. The results suggest that antibacterial effects of the cinnamon essential oil can lead to wider use of the cinnamon essential oil as a natural antibacterial agent in food.

Namen diplomske naloge je bil ovrednotiti protibakterijsko in protiadhezivno delovanje ekstraktov ajdovih in pirinih kalčkov z bakterijami vrst Staphylococcus aureus in Pseudomonas aeruginosa. Protibakterijsko delovanje ekstraktov ajdovih in pirinih kalčkov smo določili z metodo razredčevanja v mikrotitrski ploščici in z metodo difuzije. Ekstrakti ajdovih in pirinih kalčkov niso pokazali protibakterijskega delovanja pri nobeni metodi. Ekstrakti ajdovih kalčkov ne delujejo protibakterijsko do koncentracije 8,0 mg/mL, medtem ko ekstrakti pirinih kalčkov niso pokazali protibakterijske aktivnosti do koncentracije 1,57 mg/mL. Za določitev minimalne inhibitorne koncentracije (MIC) ekstraktov ajdovih in pirinih kalčkov bi bile potrebne dodatne raziskave npr. z uporabo večjih koncentracij le-teh ali drugačnih postopkov ekstrakcije. Protiadhezivno delovanje ekstraktov smo določali z metodo barvanja s kristal vijoličnim. Ekstrakti ajdovih kalčkov (0,5 in 0,1 MIC) so pri bakterijah vrste Staph. aureus povečali adhezijo, medtem ko sta ekstrakt ajdovih kalčkov (E2 pri 2,0 mg/mL) in ena od frakcij ekstrakta E2 (F4 pri 0,08 mg/mL) delovala protiadhezivno na bakterije vrste P. aeruginosa, Ekstrakt pirinih kalčkov pri 0,5 in 0,1 MIC ni imel protiadhezivnega delovanja na bakterije vrste Staph. aureus, medtem ko je pri bakterijah vrste P. aeruginosa pri 0,5 MIC adhezijo povečal. Rezultati kažejo, da bi bile smiselne nadaljnje podrobne raziskave o aktivnosti ekstraktov ajdovih kalčkov tako pri grampozitivnih kot pri gramnegativnih bakterijah. The purpose of the research was to determine the antibacterial and antiadhesive activity of buckwheat and spelt sprouts extracts against Staphylococcus aureus and Pseudomonas aeruginosa. The antibacterial activity of the extracts was determined by broth microdilution method and by agar diffusion method. The buckwheat extracts did not show any antibacterial activity up to 8,0 mg/mL and the spelt extract did not show any activity up to 1.57 mg/mL. More research is needed for minimal inhibitory concentration (MIC) determination with higher concentration of extracts or different extraction procedures. The antiadhesive activity of the extracts was determined by crystal violet staining method in a microtitre plate. The buckwheat sprouts extracts (0.5 and 0.1 MIC) increased the adhesion of Staph. aureus, but buckwheat sprouts extract (E2 at 2,0 mg/mL) and one of E2 factions (F4 at 0.08 mg/mL) decreased adhesion of P. aeruginosa. The spelt sprout extract did not show any antiadhesive activity on Staph. aureus at 0.5 and 0.1 MIC, furthermore it increased the adhesion of P. aeruginosa at 0.5 MIC. The results show that more detailed research is needed to determine the activity of buckwheat and spelt sprout extracts on gram-negative and gram-positive bacteria.

Med je naravna sladka snov, ki zaradi svojih bioaktivnih lastnosti pridobiva pomembno mesto v boju proti bakterijskim okužbam in boleznim. Zaradi protimikrobnih in protiadhezivnih lastnosti medu smo predpostavili, da bi med lahko zavrl adhezijo bakterij na zobni površini ter tako preprečil ali oslabil razvoj bolezni ustne votline. Glavni namen naše raziskave je bil ugotoviti, ali med vpliva na adhezijo bakterij na zobni površini. Za eksperimentalno delo smo izbrali bakterije vrst Streptococcus cristatus in Staphylococcus warneri, izolirane iz ustnih votlin. Z metodo razredčevanja v mikrotitrski ploščici smo določili minimalno inhibitorno koncentracijo (MIK) cvetličnega in kostanjevega medu ter medu manuke MGO 100+. Rezultati so pokazali, da so vse vrste medu imele dobro protimikrobno aktivnost. Za proučitev zmanjšanja adhezije bakterij smo z metodo barvanja s kristal vijoličnim na polistirenski površini preverili dve subinhibitorni koncentraciji (0,1 in 0,5 MIK) medu. Dober protiadhezivni učinek smo določili pri obeh koncentracijah kostanjevega medu in medu manuke MGO 100+. Zato smo protiadhezivno aktivnost medu določili tudi na zobni površini. Kostanjev med in med manuke MGO 100+ sta imela dober protiadheziven učinek na zobni površini, saj je bila inhibicija adhezije bakterij vrst Strep. cristatus in Staph. warneri od 49-85 %. Rezultati raziskave nakazujejo, da bi kostanjev med in med manuke MGO 100+ lahko uporabili kot naravni snovi v primernih formulacijah, ki bi zmanjšale adhezijo bakterij na zobno površino. To bi posledično lahko pripomoglo k zmanjšanju pojava bolezni ustne votline. Honey is a natural sweet substance gaining an increasingly important role in fight against bacterial infections and diseases because of its bioactive properties. We hypothesized that honey would reduce bacterial adhesion to dental surface because of its antimicrobial and antiadhesive properties, and thus prevent or weaken the development of oral-borne diseases. The main purpose of our study was to determine the effect of honey on bacterial adhesion on dental surface. Streptococcus cristatus and Staphylococcus warneri as oral-borne bacteria were chosen for experimental work. The minimal inhibitory concentrations (MIC) of multifloral, chestnut and Manuka MGO 100+ honeys were determined by the microdilution method. The results showed that all tested honey had a good antimicrobial activity. The reduction of bacterial adhesion was studied with two subinhibitory concentrations (0.1 and 0.5 MIC) of honey with crystal violet staining method on a polystyrene surface. A good anti-adhesive effect was determined at both concentrations of chestnut honey and Manuka MGO 100+ honey. Therefore, anti-adhesive activity of honeys was also determined on the dental surface. Chestnut honey and Manuka MGO 100+ honey had a good anti-adhesive effect on dental surface with 49-85% of adhesion inhibition on Strep. cristatus and Staph. warneri. The obtained results suggest that chestnut honey and Manuka MGO 100+ honey could be used as natural substances in suitable formulations that would reduce the adhesion of bacteria to dental surface. This could help to reduce the incidence of oral-borne disease.

V raziskavah smo okarakterizirali seve S. epidermidis izolirane iz čistih prostorov in humane seve S. epidermidis iz kliničnega okolja ter raziskali njihovo sposobnost prilagoditve na didecildimetilamonijev klorid (DDAC) in razkužilo, ki vsebuje DDAC. Občutljivost za razkužilo je bila pri 57 sevih S. epidermidis iz čistih prostorov določena z minimalno inhibitorno koncentracijo (MIK) od 1,3 do 40,8 mg/L in z MIK za DDAC od 0,1 do 4,5 mg/L, ter pri 15 humanih sevih od 10,2 do 20,4 mg/L za razkužilo in za DDAC 0,1 mg/L. Večina sevov iz čistih prostorov (96,5 %) je imela gene qacA/B in qacC, 47,4 % sevov je bilo odpornih proti gentamicinu in 3,5 % proti cefoksitinu, 40,4 % sevov iz čistih prostorov je tvorilo biofilm. 7 sevov smo izpostavili naraščajočim koncentracijam razkužila in DDAC. Sevi se na razkužilo niso prilagodili, medtem ko so se 4 sevi prilagodili na DDAC in 3 sevi so postali odporni proti DDAC. Pri tem se je MIK povečala za od 2- do 180-krat. Prilagojeni/odporni sevi so bili navzkrižno odporni proti benzalkonijevemu kloridu (3/7) in antibiotikom (4/7), imeli zmanjšano velikost celic (6/7), spremenjen maščobnokislinski profil (7/7), močnejše delovanje izlivnih črpalk (5/7) in bili močnejši tvorci biofilma (3/7) v primerjavi z neprilagojenimi sevi. Analiza diferencialno izraženih genov, RNA-seq, pri kriteriju več kot 5-kratna sprememba izražanja (FC) > 5 in statistični značilnosti (p) < 0,05 prilagojenega seva (Se11Ad) in odpornega seva (Se18To) je pokazala vključenost več različnih mehanizmov. Pri obeh sevih je bilo po prilagoditvi močno povišano delovanje izlivnih črpalk (npr. izlivna črpalka za arzenove spojine) in transportnih sistemov (npr. za aminokisline, peptide, fosfatne ione, nukleotide). Pri Se11Ad je bil pomemben mehanizem znižana aktivnost sistema Agr, kar je vodilo k povečani tvorbi biofilma, pri Se18To pa različni geni, ki sodelujejo pri sintezi celične stene, kar je vodilo do zadebelitve celične stene. Študij sevov bakterij vrste S. epidermidis in prepoznavanje mehanizmov prilagoditve in razvoja odpornosti proti razkužilom so ključnega pomena pri iskanju uspešnih strategij razkuževanja. The main objectives of our research were the characterization of Staphylococcus epidermidis strains isolated from cleanrooms and human S. epidermidis strains, and study of their adaptation to didecyldimethylammonium chloride (DDAC)-based disinfectant and to DDAC itself. The susceptibilities to the disinfectant of 57 S. epidermidis strains isolated from cleanrooms were determined according to their minimum inhibitory concentrations (MICs), which ranged from 1.3 to 40.8 mg/L for the disinfectant, and from 0.1 to 4.5 mg/L for DDAC. In 15 clinical strains, the MICs were 10.2 mg/L for the disinfectant and 0.1 mg/L for DDAC. The qacA/B and qacC genes were present in the majority of cleanroom strains (96.5%), with almost half showing resistance to gentamicin (47.4%), but with low cefoxitin resistance (3.5%) 40.4% of these cleanroom strains were biofilm formers. Seven S. epidermidis strains were exposed to gradually increased concentrations of disinfectant or DDAC. Adaptation to the disinfectant was not seen, but for DDAC, 4 strains became adapted and 3 strains became resistant. Their corresponding MICs increased from 2- to 180-fold. Compared to their non-adapted counterparts, these adapted/resistant strains became cross-resistant to benzalconium chloride (3/7) and antibiotics (4/7), showed smaller cell size (6/7), altered their fatty-acid profiles (7/7), increased their efflux pump activities (5/7), and became stronger biofilm formers (3/7). Analysis for differentially expressed genes of an adapted (Se11Ad) and a resistant (Se18To) strain using RNA-seq analysis with criterium of fold change (FC) > 5 and statistical significance (p) < 0.05, revealed several adaptation mechanisms. Both strains had up-regulated genes for efflux pumps (e.g., arsenic efflux pump) and transport systems (e.g., amino acids, peptides, phosphate ions, nucleotides transport). For Se11Ad, down-regulation of the Agr system was seen, which results in stronger biofilm formation, as an important adaptation mechanism. For Se18To, several genes involved in cell-wall synthesis were down-regulated, which resulted in thickening of the cell wall. S. epidermidis studies and knowledge of their adaptation and resistance development mechanisms are crucial for the definition of effective disinfection strategies.

Čiščenje in razkuževanje sta pomembna tekom celotne proizvodno-prodajne živilske verige. Z ustrezno metodo čiščenja in izborom razkužila lahko učinkovito preprečujemo kontaminacijo živil z nezaželenimi mikroorganizmi. V okviru diplomskega dela smo določili protibakterijsko delovanje klorheksidin diacetata. Aktivnost smo ovrednotili z določitvijo minimalne inhibitorne koncentracije (MIC) klorheksidin diacetata z bakterijami vrst Listeria monocytogenes (kot grampozitivne bakterije), Staphylococcus aureus (kot toksigene bakterije), Bacillus cereus (kot sporogene bakterije), Escherichia coli in Salmonella enterica (kot gramnegativne bakterije). MIC smo določili z metodo razredčevanja v mikrotitrski ploščici, kjer smo po dodatku reagenta INT (2-p-iodofenil-3-p-nitrofenil-5-fentil tetrazolijev klorid) določili metabolno aktivne bakterije. Število preživelih bakterij smo nato določili še z metodo štetja kolonij na trdem gojišču. Najbolj učinkovito je razkužilo delovalo na grampozitivne bakterije vrst Staph. aureus in L. monocytogenes, kjer je povprečna MIC znašala 0,9±0,3 mg/l. Povprečna MIC pri gramnegativnih bakterijah vrste E. coli je bila 1,1±0,3 mg/l in pri bakterijah vrste S. enterica 8,7±2,5 mg/l. Sporogene bakterije vrste B. cereus so imele MIC pri 1,5±0,6 mg/l. Hipotezo, da so gramnegativne bakterije vrst E. coli in S. enterica bolj odporne proti klorheksidin diacetatu kot grampozitivne bakterije vrst Staph. aureus, B. cereus in L. monocytogenes lahko potrdimo, čeprav bi za podrobnejše rezultate rabili večji obseg raziskovalnega dela. Sporogene grampozitivne bakterije vrste B. cereus so bolj odporne proti razkužilu kot nesporogene grampozitivne bakterije. Uporaba ustreznih koncentracij razkužila klorheksidina zmanjša prisotnost bakterij. Cleaning and disinfection have big importance through the production, manufacturing and distribution of food. With proper cleaning method and selection of disinfectants we can effectively prevent contamination of foods with unwanted microorganisms. Within the diploma work we investigated antibacterial activity of chlorhexidine diacetate. The activity was evaluated by determining minimum inhibitory concentration (MIC) for different bacteria, as follows, Listeria monocytogenes (as gram-positive bacterium), Staphylococcus aureus (as toxigenic bacterium), Bacillus cereus (as sporogenic bacterium), Escherichia coli and Salmonella enterica (as gram-negative bacteria). MIC was determined by micro-dilution method after adding INT reagent (2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl-tetrazolium chloride) that dyed metabolic active bacterial cells. The number of surviving bacteria was also determined with the plate count method. Chlorhexidine diacetate was the most efficient for gram-positive Staph. aureus and L. monocytogenes stains, where the MIC was 0.9±0.3 mg/l. The gram-negative E. coli strain had MIC of 1.1±0.3 mg/l. The gram-negative S. enterica strain had the highest MIC of 8.7±2.5 mg/l. Sporogenic B. cereus had MIC of 1.5±0.6 mg/l. The hypothesis that gram-negative bacteria such as E. coli and S. enterica are more resistant to chlorhexidine diacetate than gram-positive bacteria such as Staph. aureus, B. cereus and L. monocytogenes was confirmed. Sporogenic bacteria like B. cereus were more resistant than non-sporogenic gram-positive bacteria. Usage of appropriate concentrations of chlorhexidine decrease the presence of bacteria.

Aflatoksin B1 (AFB1) je strupen sekundarni presnovek nekaterih sevov plesni rodu Aspergillus, ki zaradi mnogih škodljivih lastnosti predstavlja resen problem za zdravje ljudi. Poleg tega povzroča velike ekonomske izgube v kmetijstvu in živilstvu. AFB1 najdemo v številnih živilih kot so koruza, riž, drevesni oreščki, arašidi, in suho sadje. Lahko se tvori pred ali med skladiščenjem. Učinkovit način nadzora AFB1 je ustrezen način pakiranja živila. Študije so pokazale, da so nekateri polimerni embalažni materiali dobra bariera za pline in vlago, ki sta glavna dejavnika, ki vplivata na rast plesni. Med te embalažne materiale štejemo polietilen-laminiran aluminij, etilen vinil alkohol, polipropilen in druge materiale. Učinkovitost različnih materialov proti tvorbi AFB1 je boljša z dodatkom eteričnih olj in aktivnih spojin. Zaradi okolju prijaznih lastnosti v zadnjem času vse bolj prihajajo v veljavo naravni užitni premazi za živila, kot sta hitozan in želatina s karboksimetil celulozo, ki sta prav tako učinkovitejša z dodatkom eteričnih olj. Tvorbo AFB1 lahko upočasnimo tudi s pakiranjem v atmosfero s spremenjeno plinsko sestavo (MAP). Aflatoxin B1 (AFB1) is a toxic secondary metabolite synthesized by different Aspergillus strains. Its harmful properties represent a serious problem to human health. Additionally, it causes serious economic damage in agriculture and food industry. AFB1 can be found in corn, rice, tree nuts, peanuts and dried fruits and can be produced before or during storage. An effective way to control AFB1 in foods is choosing a suitable method for packaging. Some of the polymer materials represent a barrier for gases and moisture, the major factors that have influence on growth of molds. Such polymers are polyethylene-laminated aluminium, ethylene vinyl alcohol, polypropylene and other materials. The effectiveness of different materials against the formation of AFB1 can be increased by adding essential oils and other active compounds. Edible food coatings like chitosan and carboxymethyl cellulose-gelatin film have recently become popular due to their environmentally friendly properties which also become more effective by addition of essential oils. The synthesis of AFB1 can be controlled by modified atmosphere packaging (MAP) as well.

Jabolka so sadje, razširjeno in zelo priljubljeno po celem svetu. Bogata so s fenolnimi spojinami, med katerimi so glavne katehin, klorogenska kislina in kvercetin. Vsebnost fenolov v jabolku se razlikuje glede na sorto jabolk, okoljske razmere in razmere skladiščenja. Zanimalo nas je, ali svetloba uporabljena pri optimalnih razmerah skladiščenja jabolk, vpliva na vsebnost fenolnih spojin v jabolku in če imajo le-te vpliv na bakterijsko rast, adhezijo, agregacijo in tvorbo zunajceličnih polimernih snovi (EPS) pri bakterijah vrste Escherichia coli. Ugotovili smo, da imajo jabolčni ekstrakti pred in po 18-dnevnem shranjevanju jabolk pri 10 °C pri svetlobi valovnih dolžin 420 nm in 450 nm ter v temi na bakterije vrste E. coli enako protibakterijsko aktivnost, če je le ta določena kot minimalna inhibitorna koncentracija (MIC, 6,25 % vol. jabolčnega ekstrakta oz. 1,13-1,91 mg galne kisline/ml jabolčnega ekstrakta). Po 18-dnevnem shranjevanju jabolk pri 10 °C pri svetlobi valovne dolžine 450 nm in v temi, jabolčna ekstrakta (Ekstrakt 450 3,13 % vol. in 0,78 % vol. oz. ekstrakt tema v koncentracijah 3,13 % vol., 1,56 % vol. in 0,78 % vol.) zmanjšata adhezijo bakterij vrste E. coli skoraj za polovico. Po 18-dnevnem shranjevanju jabolk pri 10 °C pri svetlobi valovnih dolžin 420 nm in 450 nm ter v temi, v koncentraciji 3,13 % vol., jabolčni ekstrakti ne vplivajo na agregacijo bakterij vrste E. coli, vplivajo pa v koncentraciji 1,56 % vol. in 0,78 % vol. Pri tem se je koncentracija sladkorjev zmanjšala iz 120 µg/ml na 50,7 µg/ml, ob dodatku Ekstrakta 420 v koncentraciji 3,13 % vol. in za polovico pri dodatku Ekstrakta 450 v koncentracijah 1,56 % vol. in 0,78 % vol. Zaključimo lahko, da jabolčni ekstrakti imajo vpliv na različne bakterijske strukture in procese vendar bi za podrobnejše poznavanje potrebovali več raziskav in analiz s katerimi bi dobili vpogled v njihovo delovanje in mehanizme. Apples are a fruit widespread and very popular all over the world. They are rich in phenolic compounds, the main ones being catechin, chlorogenic acid and quercetin. The phenol content of an apple varies according to the apple variety, environmental conditions and storage conditions. We were interested in whether the light used under optimal storage conditions of apples affects the content of phenolic compounds in the apple and if they have an effect on bacterial growth, adhesion, aggregation and formation of extracellular polymeric substances (EPS) of Escherichia coli. We found out that the apple extracts before and after 18 days of storage of apples at 10 ° C in the light of wavelengths of 420 nm and 450 nm and in the dark have the same antibacterial activity determined by MIC (6. 25% by volume of apple extract or 1.13-1.91 mg of gallic acid / ml of apple extract) on E. coli. After 18 days of storage of apples at 10 ° C in the light of wavelength 450 nm (in concentrations of 3.13% vol. and 0.78% vol.) and in the dark (in concentrations of 3.13% vol., 1.56% vol. and 0.78% vol.) reduce the adhesion of E. coli by almost half. After 18 days of storage of apples at 10 ° C in the light of wavelengths of 420 nm and 450 nm and in the dark, at a concentration of 3.13% vol. do not affect the aggregation of E. coli, but affect aggregation in the concentration of 1.56% vol. and 0.78% vol. The concentration of sugars in EPS decreased from 120 µg/ml to 50.7 µg/ml with the addition of Extract 420 at a concentration of 3.13% vol. and by half with the addition of Extract 450 in concentrations of 1.56 % vol. and 0.78 % vol. We can conclude that apple extracts have an impact on various bacterial structures and processes, but for more detailed knowledge we would need more research and analysis to get an insight into their functioning and mechanisms.

V nalogi smo se osredotočili na opis naravnih izotopskih variacij v mlečnih izdelkih iz kravjega, kozjega in ovčjega mleka iz štirih slovenskih makroregij. Kravje mleko je pokazalo statistično značilne razlike v porazdelitvi δ13Ck in δ15Nk iz štirih makroregij (p ⡤ 0,05). V povprečju smo najvišje vrednosti δ13Ck in δ15Nk določili v panonski regiji, najnižje v mediteranski regiji, alpska ter dinarska regija pa je pokazala širok interval δ13Ck in δ15Nk. Izotopska sestava kozjega in ovčjega mleka med geografskim regijami je pokazala manjše razlike kot kravje mleko. S primerjavo vrednosti δ13Ck in δ15Nk med kozjim in ovčjim sirom ter Tolmincem, večjih razlik nismo odkrili. Tolminc je pokazal zelo ozek interval vrednosti, kar povezujemo z geografskimi vplivi manjšega območja zgornjega Posočja. Kravje mleko se od mleka drobnice značilno razlikuje v porazdelitvi δ13Ck, δ15Nk ter δ18O (p ⡤ 0,05). Menimo, da razlike izhajajo iz različnega načina prireje molznih živali, izotopskih obogatitev vode v poletnih mesecih ter drugačnega načina vzorčenja. Z navzkrižnim preverjanjem smo v pravilno geografsko skupino uvrstili 47,8 % vzorcev kravjega, 71,4 % ovčjega in 66,7 % kozjega mleka. Zelo dobre rezultate navzkrižnega preverjanja je pokazalo mleko treh vrst živali, ki je bilo pravilno uvrščeno v 82,9 %. Iz rezultatov sklepamo, da na podlagi izotopske analize lahko mleko in sire le delno ločimo glede na geografsko poreklo ter različno vrsto mleka in sirov iz njih. The main goal of this work was to describe a natural variation of stable isotope ratio in a cow’s, goat and sheep dairy products from Slovenian geographical macroregions. Cow’s milk showed significant difference in the distribution of δ13Ck and δ15Nk in four regions (p ⡤ 0.05). The highest average values were determined in Pannonian region, the lowest in Mediterranean region, while Alpine and Dinaric region showed a great deviation in δ13Ck and δ15Nk values. Milk samples from goat and sheep milk showed smaller deviation in δ13Ck and δ15Nk than cow’s milk among the macroregions. Goat, sheep cheeses and cheese Tolminc didn't show significant difference in δ13Ck and δ15Nk values. Isotopic values of cheese Tolminc were distributed in a small interval, which might reflect geographic condition of upper Soča river region. Cow's milk compared with sheep and goat milk showed significant difference in the distribution of δ13Ck, δ15Nk and δ18O values (p ⡤ 0.05). These differences might originate from use of different farming system, enrichment of water due to evaporation and different sampling system. With cross classification tests 47.8% of cow's, 71.4% of sheep and 66.7% of goat milk samples were correctly classified according to Slovenian macrogeographic region. Milk samples from bovine, goat and sheep species were correctly classified in 82.9%. The results indicate that stable isotopes of bio-elements in dairy products can only partly distinguish between samples from different origin and animal species.

Namen diplomske naloge je bil določiti, ali eterično olje in hidrolat lovorja (Laurus nobilis) delujeta protimikrobno na naravno prisotne bakterije ter na bakterije vrste Listeria innocua in protiadhezivno na bakterije vrste L. innocua na solatnem listu ter vpliv obeh učinkovin na biofilm naravno prisotnih bakterij na listu zelene solate. Eterično olje (0,25 ?l/cm2 oz. 25 ?l/ml) in hidrolat (10 ?l/cm2, 20 ?l/cm2, 30 ?l/cm2) sta imela proti-biofilmski učinek na naravno prisotne bakterije. Na bakterije vrste L. innocua na solatnem listu sta eterično olje (0,25 ?l/cm2 oz. 25 ?l/ml) in hidrolat (20 ?l/cm2, 30 ?l/cm2) delovala protimikrobno. Protiadhezivni učinek na bakterije vrste L. innocua na solatnem listu je imelo eterično olje (0,13 ?l/cm2 oz. 12,5 ?l/ml, 0,25 ?l/cm2 oz. 25 ?l/ml) in hidrolat (20 ?l/cm2, 30 ?l/cm2). Rezultati našega eksperimentalnega dela kažejo, da imata eterično olje in hidrolat lovorja določeno biološko aktivnost tudi na solatnem listu, saj sta do določene mere delovala tako na naravno prisotne bakterije kot na bakterije vrste L. innocua. Za uporabo eteričnega olja ali hidrolata na ali v samem živilu bi bile potrebne obširnejše raziskave. The purpose of this thesis was to determine the antibacterial activity laurel (Laurus nobilis) essential oil and its hydrosol made against naturally occurring bacteria and Listeria innocua and antiadhesive activity against L. innocua on lettuce leaves. We assessed effect of essential oil and hydrosol on biofilm of naturally present bacteria. Essential oil (0.25 ?l/cm2 or 25 ?l/ml) and hydrosol (10 ?l/cm2, 20 ?l/cm2 30 ?l/cm2) showed antimicrobial effect on naturally present bacteria. Essential oil (0.25 ?l/cm2 or 25 ?l/ml) and hydrosol (20 ?l/cm2, 30 ?l/cm2) also showed antimicrobial activity against L. innocua inoculated on lettuce leaves. Antiadhesive effect was shown by essential oil (0.13 ?l/cm2 or 12.5 ?l/ml, 0.25 ?l/cm2 oz. 25 ?l/ml) and hydrosol (20 ?l/cm2, 30 ?l/cm2) on L. innocua inoculated on surface of lettuce. The results of this study indicated that essential oil and hydrosol of laurel do have some biological activities on salad leaves, as seen by their influence on naturally occurring bacteria and L. innocua. According to these results further work should focus on mechanisms involved in antiadhesion activity in foods.

Kot odgovor na vedno večjo potrebo po alternativnih protibakterijskih sredstvih, smo preverjali protibakterijsko delovanje eteričnih olj in hidrolatov petih izbranih zdravilnih rastlin: sladki pelin (Artemisia annua), sivka (Lavandula hybrida), laški smilj (Helichrysum italicum), nemška kamilica (Matricaria recutita) in žajbelj (Salvia officinalis) proti po Gramu negativnim bakterijam vrste Escherichia coli in po Gramu pozitivnim bakterijam vrste Staphylococcus epidermidis. Z metodo razredčevanja v mikrotitrski ploščici smo jim določili minimalno inhibitorno koncentracijo (MIC), z metodo štetja kolonij na trdnem gojišču pa smo potrdili minimalno baktericidno koncentracijo (MBC). Eterična olja so bolje delovala na po Gramu pozitivne bakterije, večina z MIC 3,13 mg/ml. MIC za po Gramu negativne bakterije so bile večinoma 6,25 mg/ml. Najbolje sta proti bakterijam učinkovali eterični olji sivke in laškega smilja, sledila sta sladki pelin in nemška kamilica. Vzorec mešanice eteričnega olja in hidrolata žajblja je imel najbolj spremenljive rezultate. Eterična olja so imela boljši protibakterijski učinek kot hidrolati. V 50 % koncentraciji ni noben inhibiral rasti bakterij. Pri 75 % in 100 % koncentraciji smo ugotovili očitno protibakterijsko delovanje samo pri hidrolatu sivke. Hidrolati sladkega pelina, laškega smilja in nemške kamilice, so sicer pokazali šibko protibakterijsko delovanje v 100 % koncentraciji, a le proti bakterijam vrste S. epidermidis. Rezultati naših eksperimentov kažejo na to, da bi lahko eterična olja in hidrolate zdravilnih rastlin uporabili kot protibakterijska sredstva tudi v živilstvu, za kar pa bi bile potrebne še dodatne raziskave. In response to the increasing need for alternative antibacterial agents, we analyzed antibacterial activity of essential oils and hydrosols of five selected medicinal plants: mugwort (Artemisia annua), lavandin (Lavandula hybrida), curry plant (Helichrysum italicum), German chamomile (Matricaria recutita) and sage (Salvia officinalis) against Escherichia coli and Staphylococcus epidermidis. Minimal inhibitory concentration (MIC) was determined using broth microdilution method. Minimal bactericidal concentration (MBC) was confirmed using plate count method. Gram-positive bacteria were more susceptible to essential oils, with most of them having MIC 3.13 mg/ml, while MIC for Gram-negative bacteria were mostly 6.25 mg/ml. Essential oils of lavandin and curry plant were the most effective, followed by mugwort and German chamomile. The sample containing sage essential oil and hydrosol had the most variable results. Essential oils had a better antibacterial effect than hydrosols. At 50 % concentration, hydrosols did not show any inhibition of bacterial growth. At 75 % and 100 % however, antibacterial activity was determined, but only for lavandin hydrosol. Mugwort, curry plant and German chamomile also showed weak antibacterial activity at 100 % concentration, but only against S. epidermidis. Results of our experiments indicate that essential oils and hydrosols of medicinal plants could also be used as antibacterial agents in food industry, which would require further research.

Namen naloge je bil preveriti, ali način osušitve rok vpliva na njihovo snažnost po umivanju. Poznamo veliko načinov osušitve rok, npr. sušenje s t. i. neskončno brisačo, sušenje s sušilnikom s toplim zrakom, sušenje s sušilnikom s hitrim izstopnim zrakom in sušenje s papirnatimi brisačkami za enkratno uporabo. Eksperimentalno delo smo opravili s prostovoljci, ki so si po predpisanem postopku umili roke, in si jih osušili s papirnatimi brisačkami za enkratno uporabo ali s sušilnikom s hitrim izstopnim zrakom. Dlani smo vzorčili pred umivanjem in po umivanju ter osušitvi rok. Za tem smo določili skupno število aerobnih mezofilnih bakterij in z njihovim povprečnim številom ovrednotili vpliv načina osušitve rok na njihovo higieno. Ugotovi smo, da uporaba sušilnika s hitrim izstopnim zrakom da primerljive rezultate kot uporaba papirnatih brisačk. Higiensko stanje sušilnika s hitrim izstopnim zrakom in papirnatih brisačk smo določili kot število aerobnih mezofilnih bakterij v zraku sušilnika in na neuporabljenih papirnatih brisačkah. Rezultati so pokazali, da so bili zračni tok sušilnika in papirnate brisačke v ustreznem higienskem stanju. Le-to je namreč predpogoj, da je osušitev rok lahko primerna. Zavedanje, da je sušenje pomemben korak pri umivanju rok, je eden od dejavnikov pri preprečitvi širjenja mikroorganizmov. The purpose of research was to check whether hand drying method affects hands hygiene after washing. There are many ways of drying hands, e.g. drying with endless towel, drying with a warm air dryer, drying with fast-exhaust air dryer and drying with disposable paper towels. Experimental work was carried out with volunteers who washed their hands and dried them with disposable paper towels or with the fast-exhaust air dryer according to the prescribed procedure. The hands were sampled before washing and after washing and drying hands. After that, the total number of aerobic mesophilic bacteria was determined and with their average number we evaluated the influence of hand drying method on its hygiene. It has been found that the use of the fast-exhaust air dryer gave comparable results to that of paper towels. The hygienic condition of the fast-exhaust air dryer and paper towels was determined as the number of aerobic mesophilic bacteria in the dryer air flow and on unused paper towels. The air of the dryer and paper towels were in good hygiene condition what is a prerequisite that hand drying may be appropriate. Awareness that hand drying is an important step in washing hands and a factor in preventing the spread of microorganisms.

Med je naravna sladka snov, ki jo čebele predelajo iz medičine ali mane z dodajanjem izločkov. Zaradi povečane bakterijske odpornosti proti antibiotikom in vedno boljšega poznavanja sestavin medu in njihovih interakcij, narašča potencial medu v boju proti boleznim povzročenih s strani bakterij. Ker ima med poznano protimikrobno in protiadhezivno aktivnost, smo predpostavili, da bi med lahko zaviral tvorbo biofilma v ustni votlini in tako preprečil naselitev in razrast patogenih bakterij in z njimi povezanih bolezni ustne votline. Proučevali smo vpliv kostanjevega medu na adhezijo bakterij vrste Streptococcus cristatus na zobno površino. Optimizirali smo metodiko določanja bakterijske adhezije na zobni površini (čiščenje zobnih površin pred bakterijsko adhezijo, način izpostavitve zobne površine bakterijam). Z optimizirano metodo smo ugotovili, da kostanjev med ni imel vpliva na adhezijo bakterij vrste Strept. cristatus na zobno površino. Da bi protiadhezivno aktivnost medu na zobni površini lahko podrobneje okarakterizirali, bi morali preizkusiti več koncentracij kostanjevega medu, spremljati kemijske lastnosti kostanjevega medu in ovrednotiti zobne površine ter pri vseh analizah uporabiti večje število le-teh. Honey is a natural sweet substance, which is produced by honey bees from nectar or honeydew by the addition of their own secretions. Due to the increased bacterial resistance to antibiotics and the increasing knowledge of honey's ingredients and their interactions, the potential of honey in the fight against bacterial-borne diseases is increasing. Since honey's antimicrobial and antiadhesive activity is well known, it has been assumed that honey will act as inhibitor in biofilm formation in oral cavity, thereby preventing attachment and spread of pathogenic bacteria and related diseases of oral cavity. We studied the impact of chestnut honey on Streptococcus cristatus adhesion on dental surface. We have optimized method for quantification of bacterial adhesion on dental surface (cleaning of tooth surfaces prior adhesion, the way of dental surface exposure to bacteria). Using the optimized method, we found that chestnut honey had no effect on Strept. cristatus adhesion to dental surface. In order to further characterize the antiadhesive activity of the honey on dental surface, several concentrations of chestnut honey should be tested, the chemical properties of chestnut honey should be analysed, dental surfaces should be evaluated and a greater number of them should be used in all analyses.

Namen diplomskega dela je bil ugotoviti, ali izbrana eterična olja (EO) delujejo protiglivno. Zato smo jim določili minimalno inhibitorno koncentracijo (MIC) ter minimalno mikrobicidno koncentracijo (MBC) ter njihovo delovanje primerjali z že uveljavljenim razkužilom – vodikovim peroksidom. Testirali smo EO origana (Origanum vulgare), grške bazilike (Ocimum basilicum), sladkega pelina (Artemisia annua), sivke (Lavandula hybrida), laškega smilja (Helichrysum italicum), rožmarina (Rosmarinus officinalis), nemške kamilice (Matricaria recutita) in žajblja (Salvia officinalis) ter vodikov peroksid s kvasovkami vrste Candida albicans in plesnimi vrste Penicillium griseofulvum. Za testiranje protiglivne aktivnosti smo uporabili metodo razredčevanja v mikrotitrski ploščici. Natančne vrednosti MIC in MBC smo za kvasovke določili z metodo štetja kolonij na trdnem gojišču, za plesni pa s pregledovanjem gojišča s plesnimi v mikrotitrskih ploščicah pod lupo. Kvasovke vrste C. albicans so bile bolj dovzetne za EO kot plesni vrste P. griseofulvum. Kvasovkam smo vrednosti MIC določili v območju

Namen naloge je bil določiti protibakterijsko delovanje eteričnih olj in hidrolatov šetraja (Satureja hortensis), lovorja (Laurus nobilis), origana (Origanum vulgare), grške bazilike (Ocimum basilicum) in rožmarina (Rosmarinus officinalis) proti bakterijam vrst Escherichia coli in Staphylococcus aureus. Med eksperimentalnim delom smo v raziskavo vključili še hidrolat morske alge (Laminaria digitata) in etanolni ekstrakt pire (Triticum aestivum ssp. spelta). Protibakterijsko delovanje omenjenih snovi smo preizkušali z metodo razredčevanja v mikrotitrski ploščici. Natančne minimalne inhibitorne koncentracije (MIC) in minimalne baktericidne koncentracije (MBC) smo določili z metodo štetja kolonij na trdem gojišču. Za bakterije vrste E. coli so se vrednosti MIC za eterična olja gibale od 1,56 mg/ml do 6,25 mg/ml, vrednosti MBC pa od 1,56 mg/ml do 12,5 mg/ml. Najboljšo protibakterijsko aktivnost je pokazalo eterično olje origana, ki je imelo najnižje vrednosti MIC. Za bakterije vrste E. coli je znašala vrednost MIC eteričnega olja origana 1,56 mg/ml, za bakterije vrste S. aureus pa 0,78 mg/ml. 50 % hidrolati niso pokazali protibakterijske aktivnosti. 75 % hidrolata šetraja in origana sta rast obeh testiranih vrst bakterij zavrla, medtem ko je bilo za inhibicijo bakterijske rasti potrebno uporabiti 100 % hidrolat rožmarina. Hidrolata lovorja in grške bazilike nista pokazala protibakterijskega delovanja. Ekstrakt pire preizkušen direktno v tekočem gojišču triptični sojin bujon (TSB) ni zavrl rasti bakterij vrste E. coli, je pa zavrl rast bakterij vrste S. aureus. Ko smo ekstrakt pire topili v etanolu in nato dodali gojišču TSB je zavrl rast obeh vrst bakterij. Eksperimentalno smo pokazali, da imajo eterična olja in hidrolati v ustrezni koncentraciji potencial zaviranja rasti bakterij in da je njihovo delovanje odvisno od vrste začimbne rastline. Eterična olja so bolj učinkovita sredstva za zaviranje rasti bakterij kot hidrolati, potrdimo pa lahko tudi, da so Gram pozitivne bakterije bolj občutljive za eterična olja in hidrolate kot Gram negativne bakterije. The purpose of our work was to determine antibacterial activity of essential oils and hydrosols made of summer savory (Satureja hortensis), laurel (Laurus nobilis), oregano (Origanum vulgare), Greek basil (Ocimum basilicum) and rosemary (Rosmarinus officinalis) against Escherichia coli and Staphylococcus aureus. During the work we decided to include also the hydrosol of sea algae (Laminaria digitata) and ethanolic extract of spelt (Triticum aestivum ssp. spelta). The main method we used to determine antibacterial activity of the substances was broth microdilution method. To get the precise minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) we performed the plate count method. For E. coli MIC values for essential oils were from 1.56 mg/ml to 6.25 mg/ml, and MBC values from 1.56 mg/ml to 12.5 mg/ml. The essential oil of oregano showed the best antibacterial activity with the lowest MIC of 1.56 mg/ml for E. coli and 0.78 mg/ml for S. aureus. In a concentration of 50 %, hydrosols did not show antibacterial activity, while 75 % hydrosols of summer savory and oregano did inhibit the growth of bacteria. As well did the 100 % hydrosol of rosemary. Hydrosols of laurel and Greek basil did not show antibacterial activity. The extract of spelt tested directly in triptic soy broth (TSB) did not inhibit growth of E. coli, but showed antibacterial activity against S. aureus. The extract of spelt diluted in ethanol and then tested in TSB inhibited growth of both tested bacteria. In this study we proved that essential oils and hydrosols do have a potential to inhibit the growth of bacteria, and that their activity differs due to plant sort. Overall, essential oils are more effective against bacteria than hydrosols. We can also confirm that Gram positive bacteria are more susceptible to essential oils and hydrosols than Gram negative bacteria.

Namen našega dela je bil ugotoviti sposobnost prilagoditve izbranih sevov listerij na benzalkonijev klorid (BAC). Z metodo razredčevanja v mikrotitrski ploščici smo določili minimalno inhibitorno koncentracijo (MIKa) BAC. MIKa za posamezen sev smo preverili z rastno krivuljo in ugotovili, da imajo na rast vseh sevov inhibitorni učinek nižje koncentracije BAC, ki so variirale med 0,125-0,5x MIKa (MIKb). Prilagoditev sevov smo zato začeli z 0,25x MIKb BAC in jo glede na prilagoditev posameznega seva nadaljevali do 128x MIKb. Na BAC se je prilagodilo 40 % sevov bakterij vrste L. monocytogenes (od 4x do 8x MIKb) in 60 % sevov bakterij vrste L. innocua (8x MIKb). Nato smo določili stabilnost prilagoditve posameznega seva na BAC. Rezultati so pokazali, da je prišlo do razvoja proti BAC odpornega seva- L. monocytogenes ŽM 500, medtem ko je pri drugih prilagojenih sevih listerij minimalna inhibitorna koncentracija BAC ostala močno povišana glede na minimalno inhibitorno koncentracijo neprilagojenih sevov. V laboratorijskih razmerah smo pri 50 % testiranih sevov listerij dobili močno zmanjšano občutljivost na BAC, kar je zelo zaskrbljujoč rezultat, ki nakazuje smeri nadaljnjega raziskovanja, s katerim bi pridobili vpogled v mehanizme prilagoditve in razvoja odpornosti listerij. Hkrati pa prikazani rezultati kažejo na sicer sprejemljivo rutinsko uporabo metode razredčevanja v mikrotitrski ploščici, ki jo je za detajlne študije nujno kombinirati z drugimi metodami. The purpose of our work was to determine the ability of selected L. innocua and L. monocytogenes strains to adapt to benzalkonium chloride (BC). The minimum inhibitory concentration (MICa) of BC was determined with broth microdilution method, and with growth curve. From the latter we determined the lowest concentration of BC that had an inhibitory effect on growth of each listeria strain. This indicated sufficiently low concentrations at which the adaptation assay was started. We found that lower concentrations of BC, between 0.125x - 0.5x MICa, have an inhibitory effect on growth of selected strains of L. monocytogenes and L. innocua. Therefore, the adaptation assay started at 0.25x MICb BC, as determined by the growth curve, using 5 strains of L. innocua and 5 strains of L. monocytogenes. BC concentration was increased stepwise for all strains, up to a concentration of 16x MICb. 40 % of L. monocytogenes and 60 % of L. innocua strains were able to adapt to the higher BC concentrations than MICb. For those strains that were adapted to the higher BC concentrations, broth microdilution method was used to determine whether MICa of adapted strains remained raised. If MICa remained constant for seven days, we concluded that a BC resistant strain had developed. Among five adapted Listeria strains, MICa remained unchanged in one of L. monocytogenes strain which is a significant proportion for laboratory conditions. These results provide a great basis for further research, which might provide a more detailed insight into mechanisms responsible for adaptation and the development of BC resistance in Listeria.

Med je v medicini poznan že dolgo časa. Zaradi svojih protimikrobnih, antioksidativnih in protivnetnih lastnosti je postal vse bolj zanimiv tudi pri preprečevanju nastanka zobnih oblog in bolezni. V raziskavi nas je zanimalo protimikrobno in protiadhezivno delovanje različnih vrst medu na seve bakterij ustne votline Streptococcus cristatus, Staphylococcus warneri in Prevotella oralis. Z metodo razredčevanja v mikrotitrski ploščici smo določili minimalno inhibitorno koncentracijo (MIK) lipovega, medu oljne ogrščice, cvetličnega, smrekovega, kostanjevega, medu manuke MGO 100+, manuke UMF 10+ in manuke MGO 400+. Z namenom, da med ne bi vplival na rast bakterij, ampak na zmanjšanje njihove adhezije, smo nato določili subinhibitorne koncentracije, ki so bile manjše od MIK (0,1, 0,3 in 0,5 MIK). Te smo uporabili za določanje protiadhezivnega delovanja medu na polistirenu z metodo barvanja s kristal vijoličnim. Rezultati so pokazali, da je imel med dobro protimikrobno aktivnost na vse izbrane seve bakterij. Najboljšo aktivnost sta imela kostanjev in smrekov med. Močan protiadhezivni učinek medu smo zaznali pri 0,5 MIK medu, medtem ko smo pri nižjih koncentracijah (0,1 in 0,3 MIK) ugotovili, da nekatere vrste medu spodbujajo adhezijo oz. jo minimalno inhibirajo. Najboljšo inhibicijo adhezije bakterij sevov Strept. cristatus ŽMJ476 in Staph. warneri ŽMJ478 so imeli med manuke, kostanjev, lipov in med oljne ogrščice. V nadaljevanju smo določili vpliv površine na protiadhezivno učinkovitost medu. Kostanjev med in med manuke MGO 100+ sta imela protiadhezivni učinek na nanohibridnem kompozitu in na amalgamskih diskih. Rezultati raziskav kažejo, da imata kostanjev med in med manuke MGO 100+ velik potencial za uporabo kot snovi oz. dodatka, ki zmanjšujeta adhezijo bakterij na površine ustne votline, vendar bi bile potrebne še dodatne raziskave. Honey has been used in medicine for a long time. Due to its antimicrobal, antioxidative and anti–inflammatory properties it became interesting in prevention of dental plaque and diseases. In our study we examined and evaluated antimicrobial and antiadhesive effect of different types of honey on oral cavity bacteria (Streptococcus cristatus, Staphylococcus warneri and Prevotella oralis). Microdilution method was used to determine minimal inhibitory concentration (MIC) of different types of honey (linden, rapeseed, flower, spruce, chestnut, manuka MGO 100+, manuka UMF 10+, manuka MGO 400+). In order not to influence the growth of bacteria, we determined subinhibitory concentration of honey which were smaller than MIC (0.1, 0.3 and 0.5 MIC). These concentrations were used to evaluate antiadhesive effect on polistyren with crystal violet staining. According to obtained results we can conclude that honey has antimicrobal effect on all tested bacteria. The best activity was found at chestnut and spruce honey. Strong antiadhesive effect has been determinated at 0.5 MIC, meanwhile some types of honey stimulated adhesion or had minimal inhibitory effect at lower concentrations (0.1 and 0.3 MIC). The best antiadhesive activity on Strept. cristatus ŽMJ476 and Staph. warneri ŽMJ478 was shown by manuka, chestnut, rapeseed and linden honey. Surface effect on adhesion was also evaluated. Chestnut honey and manuka MGO 100+ had antiadhesive effect on nanohybrid composit surface and amalgam disks. Our findings suggest that chestnut honey and manuka MGO 100+ honey have a potential for being used as an antiadhesive product in oral cavity surfaces, however further experiments are needed.

Namen dela je bil oceniti adhezijo bakterij vrst L. monocytogenes in E. coli na liste zelene solate (Lactuca sativa L.). Bakterije vrste L. monocytogenes so po kontaminaciji solatnih listov na njih dobro rastle in se adherirale pri 12 °C (4,3 ± 0,1 log cfu/g po 1 dnevu, 5,3 ± 0,2 log cfu/g po 9 dneh). Podoben trend adhezije smo zaznali pri bakterijah vrste E. coli (5,1 ± 0,1 log cfu/g po 1 dnevu, 6,4 ± 0,2 log cfu/g po 9 dneh). V nadaljnjih preiskavah so se bakterije vrste E. coli bolje adherirale na neoprane, kot na oprane solatne liste. Glede na dobljene rezultate, smo predvidevali, da ima površina solate dovolj ustreznih hranilnih snovi, ki omogočajo bakterijam vrste E. coli adhezijo in rast na solatnem listu. Dobro rast bakterij smo potrdili v vodnem izpirku solatne površine, saj so bakterije vrste E. coli iz začetnega števila 5,35 ± 0,02 log cfu/ml v 2 dneh dosegle koncentracijo 7,15 ± 0,03 log cfu/ml. Kemijske analize sladkorjev (glukoza, fruktoza, saharoza) sveže solate in solate med skladiščenjem pri 12 °C so pokazale, da se vsebnosti le-teh zmanjšujejo. Sladkorje smo določili tudi na sami površini solatnih listov, to je v vodnem izpirku solatne površine (glukoza 0,215 ± 0,131 mg/100 ± 5 cm2 fruktoza 0,121 ± 0,086 mg/100 ± 5 cm2 saharoza: 0,430 ± 0,130 mg/100 ± 5 cm2). Na površini solatnih listov smo določili tudi za bakterije izkoristljive vire dušika (nitratni dušik: 0,019 mg/100 ± 5 cm2 in amonijev dušik: 0,003 mg/100 ± 5 cm2). Rezultati naših raziskav kažejo, da so solatni listi ugodno okolje za adhezijo, kolonizacijo in rast bakterij vrst E. coli in L. monocytogenes. Pranje solatnih listov v vodi vpliva na zmanjšanje hranilnih snovi, potrebnih za bakterijsko rast in tako na zmanjšanje njihove adhezije in rasti. The purpose of this research was to assess the adhesion of L. monocytogenes and E. coli on lettuce leaves (Lactuca sativa L.). After artificial inoculation of salad leaves with L. monocytogenes these bacteria have adhered well and grown at 12°C (4.3 ± 0.1 log cfu/g, 5.3 ± 0.2 log cfu/g after 1 and 9 days, respectively). Similar adhesion trend was observed for E. coli (5.1 ± 0.1 log cfu/g, 6.5 ± 0.1 log cfu/g after 1 and 9 days, respectively). Further experiments with E. coli indicated that these bacteria adhered better on unwashed lettuce leaves than on washed one. That indicates that the surface of salad leaves have enough nutrients to allow adhesion and growth of E. coli. Therefore, we have checked the growth of E. coli in lettuce washing solution. The results revealed that E. coli grew well in lettuce washing solution as from initial concentration of 5.35 ± 0.02 log cfu/ml they reached 7.15 ± 0.03 log cfu/ml in 2 days. Chemical analysis of fresh lettuce leaves and lettuce leaves during storage showed that they contained fructose 0.71 ± 0.08 g/100g (2 days), 0.36 ± 0.15 g/100g (9 days), glucose 0.55 ± 0.10 g/100g (2 days) in 0.27 ± 0.10 g/100g (9 days) and sucrose 0.19 ± 0.04 g/100g (2 days), 0.08 ± 0.06 g/100g (9 days). All three sugars were also detected on the surface of fresh lettuce leaves (in lettuce leaves washing solution) and average amounts were: fructose 0.121 ± 0.086 mg/100 ± 5 cm2, glucose 0.215 ± 0.131 mg/100 ± 5 cm2, and sucrose 0.430 ± 0.130 mg/100 ± 5 cm2. Nitrogen compounds present on surface of lettuce leaves were determined as nitrate 0.019 mg/100 ± 5 cm2 and ammonium 0.003 mg/100 ± 5 cm2. Our results indicate that lettuce leaves represent favourable environment for adhesion, colonisation and growth of E. coli and L. monocytogenes. Washing of lettuce reduces nutrients for bacterial growth and consequently diminish the adhesion and growth of E. coli.