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Probiotics are living microorganisms with positive impact on consumer health if consumed in adequate amounts. The disadvantage of probiotic microorganisms is its considerable instability. Due to increasing demand for probiotic foods created pressure on the quality of these products. This thesis called Probiotic microorganisms in fermented milk products, examines how the quality is affected by customer behaviour. The effect of temperature (4 °C and 10 °C) and storage time for the number of lactic acid bacteria and bifidobacteria in fermented milk products (yoghurt and kefir milk) was examined by cultivation methods. The number of beneficial bacteria in baby food was also specified. Based on the results of this experiment it can be said, that the storage time significantly affects the amount of considered bacteria in fermented dairy products, but the legislative limits were met even at their expiration date. The amount of bifidobacteria in the baby food also matched the declared values. The storage temperature did not affect the amount of considered bacteria observed effect, however there was one exception. Storage of fermented dairy products at lower temperature can be recommended for customers. It is also desirable to consume these foods as fresh as possible.

The gastrointestinal microbiota of livestock is a complex and diverse ecosystem, which strongly depends and correlates with animals health. One of the many ways, how to improve the composition of this microbiota in the gastrointestinal tract, is application of probiotics, prebiotics or an appropriate combination called as synbiotics. Using subtle interventions can be achieved health benefits, increase of some indicators livestock performance and improving the economic situation of farming. The aim of the thesis was to find out the effect of prebiotics on the currently applied probiotics and the composition of the intestinal microbiota. Three groups of calves were studied. In the first one the mixture of five strains of rifampicin resistant variants of Bifidobacterium (RRBif): Bifidobacterium animalis ssp. animalis (2 strains), B. choerinum, B. thermophilum and B. longum ssp. suis was fed to 2 days old calves in a form of fermented milk. In the second group probiotics were adminestered together with prebiotics mixture contains fructooligosaccharides and galactooligosaccharides everyday. The third group without synbiotic treatment was used as a control. The numerous of main bacterial groups in gastrointestinal tract were determined by cultivation. Our results showed that applied bacteria were able to survive the passage through the gastrointestinal tract of calves. Administered bacteria persist in counts more than 107 CFU/g in the group of calves, that were fed only by probiotics and in numbers 108 CFU/g in the group of calves, that were treated by synbiotics. Furthermore a slow decrease of bifidobacterial numbers to 104 CFU / g was observed in both groups. Significant difference (p = 0.05) between the count of RRBif in probiotic and synbiotic group were determined only two days after administration of that additive. Administration of probiotics and synbiotics to calves increased the count of naturally occurring bifidobacteria, but these differences were not significant.

Probiotics are living microorganisms, which contribute to health improvement. The bacteria of the genus Bifidobacterium are one of the most commonly used probiotics. These bacteria are naturally occurring especially in the digestive tract of mammals. They affect the digestive process by helping to optimize the composition of the intestinal microbiota. The probiotic bacteria are expected to survive in the digestive tract and to be able to colonize the intestinal mucosa. The aim of this diploma thesis was to test bifidobacteria of different origin for certain functional properties. Three strains of bifidobacteria were selected: Bifidobacterium animalis ssp. lactis DAN (isolated from Danone yoghurt), Bifidobacterium bifidum JKM (isolated from infant feces) and Bifidobacterium longum ssp. suis 5/9 (isolated from feces of a calf); and tested in vitro a in vivo. The ability to survive in simulated conditions of digestive tract was tested. The bifidobacteria were exposed to low pH and bile salts. All the strains survived the conditions in unaltered amount till the end of the test. Autoaggregation was observed as well. The strain Bifidobacterium animalis ssp. lactis DAN showed average autoaggregation only 7,69 %. The other two strains had average autoaggregation 16,10 % and 79,05 %. The autoaggregation correlated with adherence. Adherence was tested on intestinal cell lines HT-29, Caco-2 and HT29-MTX, which differed in their ability to produce mucin. The strain Bifidobacterium bifidum JKM showed the best ability to adhere to intestinal cells among all the tested bifidobacteria. They best adhered to Caco-2 cells. Further, it was necessary to determine if the in vitro study is in correlation with in vivo testing and the bifidobacteria strain with the best ability to adhere will survive in the digestive tract of adult volunteers for the longest time. Rifampicin resistant variants of tested bacteria were given to adult volunteers to distinguish the introduced bifidobacteria and the bifidobacteria naturally occurring in intestine. All the tested bacteria survived the passage through the digestive tract in large numbers (106 a 107 KTJ/g), the bacteria were not detected 12th day after the introduction. None of the strains is able to permanently colonize the colon of the volunteers. The hypothesis was not confirmed that the most adherent strain in the digestive tract will survive the longest.

Nowadays, probiotic lactic acid bacteria (LAB) and bifidobacteria are plentifully exploited in food processing industry. LAB and bifidobacteria are important part of microflora of gastro intestinal tract (GIT). Probiotics (most often just lactobacilli and bifidobakteria) can be supplied to the GIT of the organism like food complements. Species identification is therefore very important. New methods of identification of LAB and bifidobacteria are based on analysis of DNA. Mostly exploited method is polymerase chain reaction (PCR). In my diploma work, genus and species specific PCRs were used for identification of different species of bacteria of genus Lactobacillus and Bifidobacterium in complex matrices of six food supplements (Zenflo, Linex Forte, Probian, Nutra Bona, GS lactobacillus Forte, Pangamin Bifi plus). Total DNA was isolated from crude lysates of cells present in tablets by magnetic particles coated by carboxyl groups . The preparation of cell lysates was optimalised. Different amounts of lysozyme (3 mg/ml, 10 mg/ml), time of incubation at laboratory temperature (1,5 hour, 3 hour) and time of incubation with SDS and proteinase K at 55 °C (1 hour, 3 hour, over all night) were tested. Isolated DNA was quantified and checked in PCR. Primers specific for genus Lactobacillus and Bifidobacterium and for species Lb. acidophilus, Lb. casei, Lb. rhamnosus and Lb. plantarum and B. animalis, B. bifidum, B. infantis, B. longum were used, respectively. All identified bacteria were in accord with the data declared by producer in 3 food supplements (Zenflo, Linex Forte and Pangamin Bifi Plus). The genus indentification was in accord with declaration of producer in other food products only (Probian, Nutra Bona, GS Laktobacily Forte).

Probiotic lactic acid bacteria and bifidobacteria are natural part of microflora of gastrointestinal tract. In the present, day they are grossly exploited in food processing industry. The aim of the work was molecular identification of bacteria of genus Lactobacillus and Bifidobacterium in complex matrices of two food additives. Total DNA was isolated from crude cell lysates by magnetic particles P(HEMA-co-GMA). Isolated DNA was amplified in genus-specific and species-specific PCRs. Amplicons were detected by agarose gel electrophoresis. Results were compared with declared specification given by producers in three different batches.