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Survival of bifidobacteria in digestive tract of adult volunteers
Morgensternová, Tereza ; Vlková, Eva (advisor) ; Jitka, Jitka (referee)
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.
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