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Lactic acid bacteria (LAB) and bifidobacteria may serve as reservoirs of antimicrobial resistance, but the risk posed by strains intentionally introduced into the agro-food chain has not yet been thoroughly investigated. The aim of our study was to evaluate whether probiotics, starter and protective cultures, and feed additives represent a risk to human health. In addition to commercial strains of LAB and bifidobacteria, isolates from human milk or colostrum, intestinal mucosa or feces, and fermented products were analyzed. Phenotypic susceptibility data of 474 strains showed that antimicrobial resistance was more common in intestinal isolates than in commercial strains. Antimicrobial resistance genes (ARGs) and mobile genetic elements (MGEs) were characterized in the whole genome sequences of 1114 strains using comparative genomics. Intrinsic ARGs were abundant in enterococci, bifidobacteria, and lactococci but were considered non-risky due to the absence of MGEs. The results revealed that 13.8% of commercial strains contained acquired ARGs, most frequently for tetracycline. We associated 75.5% of the acquired ARGs with known or novel MGEs, and their potential for transmission was assessed by examining metagenomic sequences. We confirmed that ARGs and MGEs were not as abundant or diverse in commercial strains as in human intestinal isolates or isolates from human milk, suggesting that strains intentionally introduced into the agro-food chain do not pose a significant threat. However, attention should be paid especially to individual probiotic strains containing elements that have been shown to have high potential for transferability in the gut microbiota.bAbbreviations:/bARG, antimicrobial resistance gene; ICE, integrative and conjugative element; IME, integrative and mobilizable element; LAB, lactic acid bacteria; MDR, multidrug resistance; MIC, minimum inhibitory concentration; MGE, mobile genetic element; TRRPP, tetracycline-resistant ribosomal protection protein; WGS, whole genome sequences.

The underlying mechanisms of probiotics and postbiotics are not well understood, but it is known that both affect the adaptive and innate immune responses. In addition, there is a growing concept that some probiotic strains have common core mechanisms that provide certain health benefits. Here, we aimed to elucidate the signalization of the probiotic bacterial strains Lactobacillus paragasseri K7, Limosilactobacillus fermentum L930BB, Bifidobacterium animalis subsp. animalis IM386 and Lactiplantibacillus plantarum WCFS1. We showed in in vitro experiments that the tested probiotics exhibit common TLR2‐ and TLR10‐dependent downstream signalling cascades involving inhibition of NF‐κB signal transduction. Under inflammatory conditions, the probiotics activated phosphatidylinositol 3‐kinase (PI3K)/Akt anti‐apoptotic pathways and protein kinase C (PKC)‐dependent pathways, which led to regulation of the actin cytoskeleton and tight junctions. These pathways contribute to the regeneration of the intestinal epithelium and modulation of the mucosal immune system, which, together with the inhibition of canonical TLR signalling, promote general immune tolerance. With this study we identified shared probiotic mechanisms and were the first to pinpoint the role of anti‐inflammatory probiotic signalling through TLR10.

Bifidobakterije su dominantna skupina bakterija u gastrointestinalnom traktu novorođenčadi, a u odrasloj dobi smanjuje im se brojnost. Prijenos bakterija s majke na dijete, pa tako i bifidobakterija, moguć je preko majčine kože, rodnice, djetetove usne šupljine, ali važan izvor je i majčino mlijeko koje je osim za nutritivni razvoj zaslužno i za imunosni razvoj djeteta. Oligosaharidi su nakon lipida i laktoze najzastupljenija komponenta majčinog mlijeka te funkcioniraju kao prebiotici potičući rast određenih bakterija u crijevima novorođenčadi i štiteći od kolonizacije patogenim bakterijama. Kolonizacija crijeva novorođenčadi ovisi o načinu poroda, prehrani i mikroorganizmima prisutnim u okolišu. Prve bakterije koje koloniziraju crijeva novorođenčadi su fakultativni anaerobi koji omogućuju rast striktnih anaeroba kao što su bifidobakterije. Adhezija bakterija na crijevnu sluznicu potrebna je kako bi se ostvarili zdravstveni učinci bifidobakterija kao što je smanjenje trajanje dijareje. Bifidobacterium are the dominant genus of bacteria in the gastrointestinal tract of newborns, and their number decreases in adulthood. Transmission of bacteria from mother to child, including bifidobacteria, is possible through the mother's skin, vagina, the child's oral cavity, but an important source is also breast milk. In addition to nutritional development, breast milk is also responsible for the immune development of the child. Oligosaccharides are after lactose and lipids the third most abundant component of human milk acting as prebiotics, which encourage the growth of certain bacteria within the infant gastrointestinal tract, and protecting the infant from colonisation by pathogenic bacteria. Colonization of the intestines of newborns depends on the mode of delivery, diet and microorganisms present in the environment. The first bacteria to colonize the intestines of newborns are facultative anaerobes that allow the growth of strict anaerobes such as bifidobacteria. Adhesion of bacteria to the intestinal mucosa is required to achieve the health effects of bifidobacteria such as reducing the duration of diarrhea.

Lactic acid bacteria and bifidobacteria deliberately introduced into the food chain may act as a reservoir of antimicrobial resistance genes (ARGs), which is considered a safety concern. In the present study, resistance to antimicrobials of commercial probiotic strains, probiotic candidate strains, and starter cultures (n = 20) was characterised based on integration of phenotypic and in silico data. Minimum inhibitory concentrations (MICs) of 16 antimicrobials were determined for lactobacilli and bifidobacteria that were isolated from pharmaceutical products or obtained from the manufacturers or culture collections. Using different databases and bioinformatic tools, we predicted ARGs, mutations, genomic islands, and mobile genetic elements (MGEs) in their whole genome sequences. In addition, a comprehensive in silico analysis of the prevalence of the tetW gene and its genetic environment across lactobacilli and bifidobacteria (n = 1423) was conducted. Several strains exhibited phenotypic resistance to kanamycin, tetracycline, chloramphenicol, quinupristin-dalfopristin, ciprofloxacin, or neomycin. These resistances, however, did not always correspond to the presence of ARGs and vice versa. We detected an acquired tetW gene in four commercial strains of Bifidobacterium animalis subsp. lactis, whereas homologs of antimicrobial resistance (AR) proteins were predicted in all 20 proteomes. The prevalence of the tetW gene, which was often flanked by MGEs, was higher in analysed bifidobacteria (31.9%) than lactobacilli (6.3%). In addition, sequences flanking tetW were associated with putative genomic islands and were conserved in several strains, including potential pathogens. Our findings provide an insight into AR of probiotics, probiotic candidates, and starter cultures with an emphasis on tetracycline and into the safety of these strains in the context of AR.

Raziskovali smo antibiotično odpornost mlečnokislinskih bakterij in bifidobakterij izoliranih iz črevesne sluznice. Zanimali sta nas morebiten pojav fenotipske in genotipske odpornosti. Po homogenizaciji črevesnih bioptov smo izolirali mlečnokislinske bakterije, bifidobakterije smo že imeli izolirane in smo jih vzeli iz mikrobiološke zbirke. Izolate smo z metodo RAPD pregledali za vrstno pestrost in za nadaljnjo analizo izbrali tiste z unikatnimi vzorci pomnožkov. Po izolaciji DNA in namnožitvi 16S rDNA, smo identifikacijo izvedli glede na rezultate sekvenciranja pomnožkov. Sledilo je preverjanje fenotipske odpornosti z metodo razredčevanja v mikrotitrski ploščici. Glede na mejne vrednosti, ki jih je postavila EFSA, je previsoke MIC izkazalo 14 sevov od skupno 104, devet proti eritromicinu, štirje proti tetraciklinu in eden proti kanamicinu. Sev B. longum 34-7 v svoji dednini nosi zapis za gen erm(B), sevu B. adolescentis IM677 smo potrdili prisotnost gena tet(O) in sevu B. longum 34-8 pa prisotnost gena tet(W). Pri nobenem izmed testiranih sevov nismo potrdili prisotnosti genov za odpornost proti kanamicinu. Ker odpornostnih genov nismo našli pri vseh sevih, ki so izkazali fenotipsko odpornost je ta najverjetneje posledica mutacij, ali pa genov, ki jih ne poznamo oz. jih nismo vključili v raziskavo. The aim of the study was to search for antibiotic (erythromycin, tetracycline and/or kanamycin) resistance among lactic acid bacteria (LAB) and bifidobacteria isolated from children's intestinal mucosa. We were searching for signs of phenotypic or genotypic antibiotic resistance. First we homogenized intestinal biopsy samples and isolated LAB, bifidoacteria strains had already been isolated. LAB isolates were screened with RAPD to see how related they are, for further analysis we chose the ones with uniqe M13 bands. After DNA isolation and 16S rDNA amplification isolates were sent for sequencing to determine their genus or species. Further on, we tested the LAB and bifidobacterial isolates for phenotypic resistance with microdilution method. At microdilution test 14 out of 104 strains showed resistance against antibiotics, nine strains against erythromycin, four strains against tetracycline and one strain against kanamycin. Those 14 strains with high MIC were later on screened with PCR to see if they contain any of resistance genes. Out of 14 strains that showed phenotypic resistance we discovered that one strain of B. longum (34-7) carries gene for erythromycin resistance erm(B) in his DNA, one strain of B. adolescetnis (IM677) carries gene for tetracycline resistance tet(O), strain B. longum (34-8) carries gene tet(W). None of the strains tested carried genes for resistance against kanamycine.

Tretiranje hrane ultrazvukom je relativno novi način procesiranja hrane, a razvijen je u posljednja dva desetljeća. Koristi se, između ostalog, prilikom fermentacije mlijeka, za smanjenje broja štetnih mikroorganizama, ali i za stimulaciju rasta probiotičkih bakterija u mlijeku, a naročito bifidobakterija. Najčešće korištene probiotičke kulture pri proizvodnji fermentiranih mliječnih proizvoda jesu upravo bifidobakterije. Glavni problem njihove upotrebe je što mlijeko nije prirodna sredina za njihov rast i preživljavanje stoga je njihovo korištenje u fermentaciji mlijeka ograničeno. Pokazalo se da primjena ultrazvuka visokog intenziteta može skratiti trajanje fermentacije kod mlijeka fermentiranog s B. infantis, B. brevi i B. animalis subsp. lactis. Isto tako, pokazalo se da je mehanizam stimulacije rasta bifidobakterija ultrazvučnim tretiranjem povezan s kinetikom ugljikohidrata i organskih kiselina tijekom fermentacije. Cilj ovoga rada je prikazati kako upotrebom ultrazvuka visokog intenziteta dolazi do stimulacije rasta bifidobakterija u mlijeku, a samim time do ubrzanja procesa fermentacije., Treating food by ultrasound is a relatively novel food processing method which has been developed in the last two decades. When considering milk processing, ultrasound might be used to reduce the count of harmful microorganisms, and to stimulate the growth of probiotic bacteria during milk fermentation, especially bifidobacteria. The most commonly used probiotic cultures in fermented dairy products are bifidobacteria. The main problem related to the fermentation by bifidobacteria is that milk does not provide a natural environment for their growth and survival. Thus the application of bifidobacteria in milk fermentation is limited. Many studies indicated that the application of high intensity ultrasound (20 kHz) may shorten the duration of milk fermentation by B. infantis, B. brevi and B. animalis subsp. lactis. Also, studies showed that the stimulating mechanism of bifidobacteria growth by ultrasound was associated with the kinetics of carbohydrates and organic acids during fermentation. The aim of this review was to demonstrate how the application of the high intensity ultrasound stimulates the growth of bifidobacteria in the milk, and thus improves the fermentation process.

Namen magistrske naloge je bil raziskati, ali mlečnokislinske bakterije, predvsem laktobacili, in bifidobakterije iz humanega mleka, kolostruma in zrelega mleka, vsebujejo gene za odpornost proti tetraciklinu in eritromicinu, kar predstavlja določeno tveganje za prenos odpornosti na patogene bakterije v dojenčkovem črevesju. Odpornost proti kanamicinu smo priključili iz razloga, ker je bila v predhodnih raziskavah teh sevov nepričakovano pogosta. Tako smo raziskali, ali so v njihovem genomu prisotni pridobljeni geni z zapisi za odpornost proti izbranim antibiotikom. En vzorec kolostruma in 38 vzorcev mleka smo nacepili na gojišči Rogosa in WCA-mup ter osamili 243 izolatov. Rezultati sekvenciranja izolirane DNA so pokazali, da smo s teh gojišč osamili bakterije iz rodov Lactobacillus, Propionibacterium, Streptococcus, Bifidobacterium in Actinomyces. Tem izolatom smo priključili še 56 predhodno izoliranih bakterijskih sevov iz rodov Lactobacillus in Bifidobacterium. Fenotipsko odpornost smo ugotavljali s pomočjo mikrodilucije. Pri sevih, ki so izkazovali fenotipsko odpornost proti določenemu antibiotiku, smo z uporabo PCR metode preverjali prisotnost najbolj znanih genov, povezanih z odpornostjo proti temu antibiotiku. Fenotipsko odpornost proti eritromicinu smo zaznali pri 3 sevih, proti tetraciklinu pri 10 sevih in proti kanamicinu pri 52 sevih, medtem ko prisotnosti genov erm(A), erm(B), erm(C), erm(T), tet(A), tet(B), tet(C), tet(M), tet(O), tet(W), aac(6’)-aph(2’’), ant(6)-Ia in aph(3’)-IIIa nismo potrdili pri nobenem od teh sevov. The aim of this master's thesis was to investigate whether lactic acid bacteria, especially lactobacilli, and bifidobacteria from human milk, colostrum and mature milk, contain tetracycline and erythromycin resistance genes, which presents a certain risk of spread of antibiotic resistance to pathogenic bacteria in the infant's gut. Kanamycin was subsequently added to the study for a reason that in previous studies the resistance of lactobacili to this antibiotic was unexpectedly frequent. Thus, we investigated whether the genes associated with the resistance to selected antibiotics are present in the genome of lactic acid bacteria and bifidobacteria. One sample of colostrum and 38 samples of milk were plated on Rogosa and WCA-mup medium. 243 bacterial strains were isolated. The results of the sequencing of isolated DNA showed that bacteria belonged to the genera Lactobacillus, Propionibacterium, Streptococcus, Bifidobacterium and Actinomyces. We also included 56 pre-isolated bacterial strains from the genera Lactobacillus and Bifidobacterium. Phenotypic resistance was determined by microdilution. In phenotypic resistant strains we investigated the presence of the most well-known genes associated with resistance to a particular antibiotic with PCR. Phenotypic resistance to erythromycin was detected in 3 strains, tetracycline in 10 strains, and kanamycin in 52 strains, while the presence of investigated genes erm(A), erm(B), erm(C), erm(T), tet(A), tet(B), tet(C), tet(M), tet(O), tet(W), aac(6')-aph(2''), ant(6)-Ia and aph(3')-IIIa has not been confirmed in any of the strains.

Celiakija je imunsko posredovana sistemska bolezen, ki je posledica uživanja glutena. Edini do sedaj učinkovit način zdravljenja je brezglutenska dieta (BGD), dosledno izvajanje le-te pa predstavlja težavo za mnoge osebe s celiakijo. Pri nekaterih osebah kljub strogi BGD simptomi bolezni vztrajajo in pri 40¬¬–50 % je vnetje še vedno prisotno. V več študijah je bilo ugotovljeno, da imajo osebe s celiakijo neravnovesno črevesno mikrobioto (povečan delež gramnegativnih bakterij in zmanjšan delež bifidobakterij), ki ima pomembno vlogo v patogenezi bolezni. Tudi po uvedbi BGD imajo te osebe še vedno zmanjšan delež bifidobakterij. Določene vrste Bifidobacterium breve so v in vitro študijah delovale protivnetno. Cilj doktorske disertacije je bil ugotoviti vpliv 3-mesečnega jemanja Bifidobacterium breve BR03 in B632 (v nadaljevanju probiotik) na provnetni citokin dejavnik tumorske nekroze alfa (TNF-α), protivnetni citokin interlevkin 10 (IL-10) v serumu in na raven kratkoverižnih maščobnih kislin (KVMK) v blatu pri otrocih s celiakijo na BGD. V raziskavo smo vključili 10 otrok z na novo odkrito aktivno celiakijo, 49 otrok s celiakijo na BGD in 18 zdravih otrok. Otroke s celiakijo na BGD smo randomizirali v dve skupini. Prva skupina je 3 mesece prejemala probiotik, druga skupina pa placebo. Meritve citokinov TNF-α in IL-10 so potekale po navodilih proizvajalca z metodo kemiluminiscence na aparatu Immulite One. Iz vzorcev blata smo s pomočjo visokozmogljivostne tekočinske kromatografije analizirali ocetno, propionsko, masleno in mlečno kislino. Fermentacijski indeks ([ocetna kislina] – ([propionska kislina] + [n-maslena kislina]) / [skupne KVMK]) smo uporabili za prikaz vnetnega količnika KVMK. Pri otrocih s celiakijo na BGD je prišlo po jemanju probiotika do značilnega znižanja TNF-α. Ob kontroli, 3 mesece po koncu jemanja probiotika, se je raven TNF-α ponovno značilno dvignila. Vrednosti IL-10 so bile pri večini otrok pod ravnjo kvantifiacije. Otroci z aktivno celiakijo so imeli značilno višje začetne vrednosti ocetne in propionske kisline v blatu v primerjavi z zdravimi otroki. Otroci s celiakijo na BGD so imeli značilno več propionske kisline v primerjavi z zdravimi otroki. Vrednosti mlečne kisline so bile pri večini otrok pod ravnjo kvantifikacije. Po jemanju probiotika ni prišlo do značilnih sprememb vrednosti KVMK v blatu. Fermentacijski indeks (FI) se je 3 mesece po koncu uživanju probiotika še značilno znižal, kar nakazuje zmanjšanje vnetja na ravni črevesja. Z raziskavo smo dokazali, da sta izbrana probiotična seva Bifidobacterium breve BR03 in B632 delovala protivnetno, saj so se po jemanju le-teh vrednosti TNF-α v serumu značilno znižale in nakazano se je znižal FI, ki ponazarja aktivnost kroničnega, s črevesno floro povezanega vnetja. Celiac disease (CD) is an immune-mediated disorder triggered by ingestion of gluten. Gluten-free diet (GFD) has so far proved to be the only effective treatment. Many patients with CD have problems with full compliance to GFD. Symptoms persist in some patients despite strict GFD and in 40¬¬–50 % of them inflammation is still present. Increasing evidence suggests that persons with CD have gut microbiota dysbiosis (increased number of Gram negative bacteria and decreased number of bifidobacteria), which play an important role in the disease pathogenesis. Even after a long-term treatment with GFD patients have a decreased number of bifidobacteria. Some strains of Bifidobacterium breve have shown in vitro anti-inflammatory effect on the gut level. The aim of doctoral dissertation was to investigate the influence of three months administration of Bifidobacterium breve BR03 and B632 (afterwards probiotic) on the pro-inflammatory cytokine tumor necrosis factor alpha (TNF-α), anti-inflammatory cytokine interleukin 10 (IL-10) in serum and on the level of short chain fatty acids (SCFA) in faeces of children with celiac disease on GFD. Clinical study was conducted on 10 children with newly diagnosed active CD, 49 children with CD on GFD and 18 healthy children. Children with CD on GFD were randomized in two groups. The first group received probiotic for three months and the second group was administered placebo. Measurements of cytokines TNF-α and IL-10 was performed according to the manufacturer’s instructions with chemiluminescent immunometric assay in Immulite One. Faecal samples were analyzed for acetic, propionic, butyric and lactic acid with high performance liquid chromatography. Fermentation index ([acetic acid] – ([propionic acid] + [n-butyric acid]) / [total SCFAs]) was used for the assessment of inflammatory status in the gut of patients. TNF-α levels were significantly decreased in children with CD on GFD after receiving probiotics for three months. At checkup, three months after the end of intervention with probiotics, TNF-α significantly increased again. IL-10 levels were below the detection level in most of the children. Children with an active CD had significantly higher baseline levels of acetic and propionic acid in faeces compared to healthy children. Children with CD on GFD had significantly higher baseline levels of propionic acid in faeces compared to the healthy children. Lactic acid levels were below detection level in most of the children. After probiotic administration there was no significant differences in individual SCFA levels in faeces. However, faecal fermentation index was significantly decreased three months after the end of probiotic intervention, suggesting a decrease of inflammation on the gut level. Our study has shown that selected B. breve strains have an anti-inflammatory effect. After administration of the probiotic, TNF-α levels in serum as well as faecal FI decreased, which represents chronical, gut microbiota-mediated inflammation.

Galactooligosaccharides (GOS) are an important class of dietary prebiotics that exert beneficial effects on intestinal microbiota and gut barrier function. In this study, high-purity GOS (HP-GOS) were investigated in vitro and in vivo and confirmed as prebiotic ingredients in rat diet. HP-GOS were successfully produced using a two-step process, enzymatic hydrolysis and fermentation by yeast. They were found to serve as a good substrate and carbon source for supporting the growth of probiotic bacteria more effectively than other commercial GOS. Following administration of 1 % (by mass) of HP-GOS to rats, the growth of Bifidobacterium bifidum and B. longum in the gut increased most rapidly up to 12 h, and thereafter the increase was slow. Therefore, 1 % HP-GOS was found to be acceptable for the growth of probiotic bacteria. Groups of animals that were orally administered HP-GOS and bifidobacteria during the study, and the group administered HP-GOS during the 2nd (days 13–15) and 4th (days 28–30) period of the study had significantly (p, Galaktooligosaharidi su važna klasa prebiotika koji blagotvorno djeluju na mikroorganizme probavnog trakta i time štite stijenke probavnih organa. U radu je ispitan in vitro i in vivo prebiotički učinak pročišćenih galaktooligosaharida, dodanih hrani za štakore. Pročišćeni galaktooligosaharidi uspješno su proizvedeni enzimskom hidrolizom i fermentacijom s pomoću kvasca. U usporedbi s galaktooligosaharidima dostupnim na tržištu, znatno su bolji izvor ugljika te podloga za rast probiotičkih bakterija. Nakon dodatka 1 % masenog udjela pročišćenih galaktooligosaharida hrani, bitno se povećao rast bakterija Bifidobacterium bifidum i B. longum u probavnom traktu štakora tijekom 12 sati, nakon čega je rast bio nešto sporiji. Zaključeno je da ta doza galaktooligosaharida ima prebiotički učinak. Skupine životinja dohranjivane pročišćenim galaktooligosaharidima i bifidobakterijama te skupina dohranjena galaktooligosaharidima nakon 13-15 i 28-30 dana uzgoja imale su bitno veći (p˂0,05) broj bakterija u izmetu od skupina dohranjenih samo jednom dozom bifidobakterija. Pročišćeni galaktooligosaharidi utjecali su na ekspresiju gena koji kodiraju GLP-1 (peptid sličan glukagonu) i peptid YY (PYY). Nakon dohrane prebioticima i bifidobakterijama došlo je do pojačane uzvodne transkripcije mRNA u genima za GLP-1 i PYY. Stoga smatramo da se pročišćeni galaktooligosaharidi zbog dragocjenih prebiotičkih svojstava mogu upotrijebiti u proizvodnji funkcionalne hrane.

Kadmijum je široko prisutni toksikant životne sredine, koji izaziva različite poremećaje u biološkim sistemima, uklјučujući tu i bubrežnu disfunkciju i degeneraciju tkiva jetre. Sa druge strane, pretpostavlјa se da su pozitivne osobine probiotskih bakterija u vezi sa njihovom sposobnošću da vezuju različite ligande, što dovodi do pobolјšanja crevne mikrobijalne ravnoteže i drugih koristi za domaćina. Imajući u vidu pomenuta, ova studija je sprovedena da istraži zaštitni efekat probiotika protiv kadmijum-indukovanog toksičnosti kod pacova. Muški pacovi Rattus norvegicus Wistar soja, težine 130±10 g, gajeni su u standardnim laboratorijskim uslovima (22±2°C, režim 12h svetlo/12h mrak) u metaboličkim kavezima (3 pacova/kavezu). Životinje su podeljene u četiri grupe: 1) kontrolne jedinke; 2) životinje tretirane probioticima; 3) životinje koje su primale kadmijum u formi CdCl2; i 4) životinje tretirane probioticima i kadmijumom. U krvi je određivana koncentracija kadmijuma, aktivnost alanin aminotransferaze (ALT) i aspartat aminotransferaze (AST), kao i nivoi adrenalina i noradrenalina. U homogenatima tkiva jetre i bubrega određivane su koncentracije kadmijuma, cinka i bakra, kao i aktivnosti ukupne superoksid dismutaze (SOD) i katalaze (CAT). Takođe, ispitivan je i histomorfološki profil tkiva jetre i bubrega u svim grupama životinja. U fecesu eksperimentalnih životinja određivana je koncentracija kadmijuma i mikrobijalni profil odabranih vrsta bakterija crevne mikroflore. Na kraju, Comet testom je testirana genotoksičnost kadmijuma in vitro and in vivo. Na osnovu naših rezultata mogu se izvesti sledeći zaključci:Davanje kadmijuma eksperimentalnim životinjama u formi kadmijum hlorida i koncentraciji 70ppm u pijaćoj vodi izaziva značajno smanjenje u porastu telesne mase tokom 5 nedelja eksperimenta... Cadmium is a ubiquitous environmental toxicant that causes a variety of disturbances in biological systems, including renal dysfunction and liver tissue degeneration. On the other hand, it is supposed that beneficial properties of probiotic bacteria are related to their capacity to adhere or bind different targets, thus leading to improved intestinal microbial balance and other benefits to host. Bearing aforementioned in mind, the present study was undertaken to investigate the protective effect of probiotic supplementation against cadmium-induced toxicity in rat. Male Wistar rats Rattus norvegicus, weighing 130±10 g, were acclimated to 22±2°C in metabolic cages (3 rats/cage) and maintained under a 12h light/12h dark cycle. Animals were divided into four groups: 1) controls; 2) probiotics treated; 3) CdCl2 treated; and 4) probiotics + CdCl2 treated. The cadmium concentrations were obtained in the blood, liver, kidney, and feces, as well as the blood alanine aminotransferase (ALT), aspartate aminotransferase (AST), adrenaline and noradrenaline activities. Furthermore, histomorphological changes of liver and kidney were determined, as well as the level of total supeoxide dismutase (SOD) and catalase (CAT) activities, and zinc and cooper concentration. Finally, cadmium genotoxicity were determined both in vitro and in vivo by Comet test, as well as the alterations in the fecal microflora content. Based on our results we can conclude that:1. Exposure of rats to cadmium chloride (70ppm) alone resulted in significant decrease in body weight gain compared with the control group...

Taking in consideration the long time for whey fermentation using probiotic bacteria, the aim of this research was to determine if prior enzymatic hydrolysis of lactose influences microbial activities of Lactobacillus acidophilus La-5 or Bifidobacterium animalis subsp. lactis BB-12 in reconstituted sweet whey. During fermentation (at 37 °C), pH-value and viable cell counts were monitored. The fermented samples were sensory profiled. Lactose hydrolysis shortened the fermentation time of Lactobacillus acidophilus La-5 by 2 h, and viable cell count at the end of fermentation time was greater in hydrolyzed whey sample (~9.45 log10 CFU/mL) when compared with the control sample (~8.91 log10 CFU/mL). In contrast, lactose hydrolysis in whey did not enhance the activity of Bifidobacterium animalis subsp. lactis BB-12. Lactose hydrolysis had slightly influence on sensory score of fermented samples, probably due to sweetness that masked the acidic taste of the product., Uzimajući u obzir dužinu fermentacije sirutke probiotičkim bakterijama, cilj ovog rada bio je ispitati utječe li prethodna enzimska hidroliza laktoze na aktivnost bakterije Lactobacillus acidophilus La-5 ili Bifidobacterium animalis subsp. lactis BB-12 u rekonstituiranoj slatkoj sirutki. Tijekom fermentacije (pri 37 °C) praćena je promjena pH-vrijednosti i broj živih bakterijskih stanica. Fermentirani uzorci su senzorski analizirani. Hidroliza laktoze skratila je fermentaciju sirutke s Lactobacillus acidophilus La-5 za oko 2 sata, a broj živih bakterija na kraju fermentacije bio je nešto veći u hidroliziranoj sirutki (~9,45 log10 CFU/mL), u odnosu na kontrolni uzorak (~8,91 log10 CFU/mL). Međutim, hidroliza laktoze nije utjecala na aktivnost bakterije Bifidobacterium animalis subsp. lactis BB-12. Hidroliza laktoze neznatno je utjecala na senzorska svojstva fermentirane sirutke, jer vjerojatno stvorenu kiselinu prikriva osjet slatkoće.

U radu je ispitivan rast probiotskih bakterija Lactobacillus acidophillus La5 i Bifidobacterium lactis Bb12 u komercijalnom kravljem, kozjem i sojinom mleku. Fermentacija je obavljena na 37 C do približno pH-vrednosti 4, 6. Bifidobakterije su najbolje rasle u sojinom mlijeku gde je fermentacija bila dvostruko kraća nego u kozjem i kravljem mleku. S druge strane, laktobacili su mnogo bolje rasli u kravljem, a najbolje u kozjem mleku, dok je njihov broj u sojinom mleku na kraju fermentacije ostao na nivou inokulacije.

Cilj rada bio je ispitati mikrobiološka i senzorska svojstva kozjeg i kravljeg mlijeka fermentiranog probiotičkim bakterijama Bifidobacterium longum Bb-46 i Bifidobacterium bifidum Bb-12 tijekom čuvanja. Osim s navedene dvije DVS komercijalne starter kulture, kozje i kravlje mlijeko fermentirani su probiotičkim sojevima bifidobakterija izoliranim iz ljudskog organizma (B. bifidum B 3.2, B. bifidum B 7.1 i B. longum B 6.1). Svrha rada bila je usporediti sposobnost preživljavanja ispitivanih sojeva u fermentiranom kozjem mlijeku, u odnosu na fermentirano kravlje mlijeko. Rezultati rada pokazali su da je veći broj svih ispitivanih sojeva bifidobakterija nastao tijekom fermentacije kozjeg mlijeka u odnosu na kravlje. Održivost bifidobakterija u fermentiranom kozjem i kravljem mlijeku tijekom skladištenja varirala je ovisno o soju. Rezultati rada pokazali su da nije bilo značajne razlike u održivosti tijekom čuvanja između komercijalnih DVS i humanih sojeva bifidobakterija. Nadalje, rezultati kretanja broja bifidobakterija i pH vrijednosti pokazali su da nema značajnih razlika u sposobnosti preživljavanja odabranih sojeva u fermentiranom kozjem u odnosu na fermentirano kravlje mlijeko. Razlikovale su se međutim tendencije kretanja broja bifidobakterija u kozjem u odnosu na kravlje mlijeko tijekom perioda čuvanja. Sveukupno, rezultati pokazuju da je optimalno vrijeme čuvanja većine probiotičkih fermentiranih proizvoda 12-15 dana, što su pokazali i rezultati senzorskih ocjenjivanja.

Praćenjem parametara kinetike fermentacije utvrđen je utjecaj različitih bakterijskih kultura na brznu fermentacije kozjeg mlijeka uz dodatak meda. Za inokulaciju mlijeka korištene su mezofilna kultura CH-N19 (Lactococcus lactis subsp. diacetilactis, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. mesentericus i Leuconostoc mesenteroides subsp. lactis), Bb46 – probiotičke bakterije (Bifidobacterium longum), Lactobacillus plantarum, jogurtna kultura (Streptococcus thermophilus i Lactobacillus delbrueckii subsp. bulgaricus) – termofilne bakterije. Fermentacija kozjeg mlijeka probiotičkim bakterijama Bb46 i Lactobacillus plantarum vođena je na 37 &ordm ; C, s CH-N19 na 22 &ordm ; C, te za jogurtnu kulturu na 41, 5 &ordm ; C. Utvrđene su razlike trajanja i tijeka fermentacije. Dodatak meda je povoljno utjecao na brzinu fermentacije kozjeg mlijeka. Grafički su prikazane sve značajne ovisnosti mjerenih parametara kinetike procesa i posebno su istaknute korelacije praćenih parametara.

Za inokulaciju kozjeg i kravljeg mlijeka korištene su ABT-2 kultura (Lactobacillus acidophilus, Bifidobacterium lactis Bb-12, Streptococcus thermophilus) i mezofilne CH-N19 kultura (Lactococcus lactis subsp. diacetylactis, Lactococcus lactis subsp. lactis, Lactococcus lactis subsp. mesentericus, Leuconostoc mesenteroides subsp. lactis). Fermentacija kozjeg i kravljeg mlijeka nacijepljenih ABT-2 kulturom vođena je na 37 °C kroz 8 sati, a sa CH-N19 starterom na 24 °C kroz 24 sata. Utvrđene su značajne razlike tijeka i trajanja fermentacije. Pokazalo se da sve odabrane mliječno kisele bakterije brže rastu i bolje fermentiraju kozje mlijeko. Krivulje rasta mliječno kiselih bakterija bile su u potpunoj korelaciji s brzinom nastajanja mliječne kiseline i promjenom pH vrijednosti do određenog perioda fermentacije, nakon čega odnos CFU-pH nije bio u statistički značajnoj korelaciji. Veći koeficijenti korelacije između spomenutih parametara zabilježene su u kozjem mlijeku.

Radi sve veće popularizacije proizvoda prirodnog podrijetla, osobito u području prehrane i prehrambenih aditiva, u posljednje je vrijeme intenzivirana uporaba sporo apsorbirajućih i neapsorbirajućih šećera kao supstrata za bakterije mliječne kiseline i kao prebiotika za ljudsku prehranu. Ljudsko debelo crijevo sadrži veliku koncentraciju bakterija (10000000000000 po gramu suhe tvari sadržaja debelog crijeva), a noviji radovi pokazuju da bifidobakterije i laktobacili, najbrojnije uobičajene anaerobne bakterije u mikroflori ljudskog debelog crijeva, korisno djeluju na zdravlje domaćina. Glavni čimbenik za razmnožavanje bifidobakterija u ljudskom probavnom sustavu je dijetalni šećer, pa korištenje neprobavljivih oligosaharida - kao što su rafinoza, fruktooligosaharidi, galaktozillaktoza, izomaltooligosaharidi ili transgalaktozilo-ligosaharidi - uzrokuju porast broja endogenih bifidobakterija i neke promjene kod bakterija mliječne kiseline. U radu su prikazani pregledi prebiotika i njihovih osobina kao i kriteriji za selekciju te sigurnost prebiotika i supstrata., There is an increasing consumer demand for natural products, particularly in the area of food or food additives. This has created some possibilities for the use of slowly absorbable and nonabsorbable sugars as substrates for lactic acid bacteria and as prebiotics for human nutrition. The human colon contains a high concentration of bacteria (10000000000000 per gram dry weight of colonic contents). Recent studies show that bifidobacteria and lactobacilli are among the common anaerobic bacteria in the human colonic microflora and may exert beneficial effects on the host. Dietary sugar source is the main factor affecting the multiplication of bifidobacteria in the human intestine. Consequently, the administration of nondigestible oligosaccharides such as raffinose, fructooligosaccharides, galactosyllactose, isomaltooligosaccharides, or transgalactosyloligosaccharied causes an increase in the number of endogenous bifidobacteria and some changes in lactic acid bacteria. In this paper prebiotics and theirs charasteristis were described as also criteria for selection and safety of prebiotics and substrates.

Radi sve veće popularizacije proizvoda prirodnog podrijetla, osobito u području prehrane i prehrambenih aditiva, u posljednje je vrijeme intenzivirana uporaba sporo apsorbirajućih i neapsorbirajućih šećera kao supstrata za bakterije mliječne kiseline i kao prebiotika za ljudsku prehranu. Ljudsko debelo crijevo sadrži veliku koncentraciju bakterija (10 na 12 po gramu suhe tvari sadržaja debelog crijeva), a noviji radovi pokazuju da bifidobakterije i laktobacili, najbrojnije uobičajene anaerobne bakterije u mikroflori ljudskog debelog crijeva, korisno djeluju na zdravlje domaćina. Glavni čimbenik za razmnožavanje bifidobakterija u ljudskom probavnom sustavu je dijetalni šećer, pa korištenje neprobavljivih oligosaharida kao što su rafinoza, fruktooligosaharidi, galaktozillaktoza, izomaltooligosaharidi ili transgalaktoziloligosaharidi, uzrokuju porast broja endogenih bifidobakterija i neke promjene kod bakterija mliječne kiseline. U radu su prikazani pregledi prebiotika i njihovih osobina kao i kriteriji za selekciju te sigurnost prebiotika i supstrata.

Fermentirani mliječni proizvodi koji sadrže bakterije mliječne kiseline vrlo povoljno djeluju na zdravlje čovjeka. Posebno se ističe njihova vrijednost pri obnavljanju zdravstveno povoljne crijevne populacije. Bakterije mliječne kiseline, koje su stoljećima sastavni dio ljudske prehrane, mogu se smatrati prirodnim načinom opskrbe probavnog sustava aktivnim tvarima. Takove aktivne tvari su npr. enzimi (laktaza, reduktaza) i tvari koje antagonistički djeluju na nepoželjnu mikrobnu populaciju u probavnom sustavu čovjeka. Brojna istraživanja, in vitro, pokazala su različitu osjetljivost bakterija mliječne kiseline prema niskom pH i koncentraciji žuči u probavnom sustavu čovjeka. Tako su bakterije Lactobacillus bulgaricus/Streptococcus thermophilus (mljekarska kultura za proizvodnju jogurta) osjetljiviji na nizak pH i veće koncentracije žuči od bakterija Lactobacillus acidophilus, Lactobacillus casei/Bifidobacteria (Marteau i sur. 1993). Bifidobakterije i Lactobacillus acidophilus mogu se razvijati i opstati u probavnom sustavu čovjeka te proizvoditi važne tvari, koje priječe rast patogenih bakterija., Fermented dairy products have particularly good influence on human health. Also, their importance is accentuated revival of beneficial intestinal microorganisms. It is quoted that Bifidobacteria and Lactobacillus acidophilus could develop and exist in human digestive tract and produce some important substances preventing pathogenic bacteria growth.