Bile salt toxicity to some bifidobacteria strains: role of conjugated bile salt hydrolase and pH |
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Authors: | Grill J P Perrin S Schneider F |
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Institution: | Laboratoire de Biochimie des Bactéries Gram+, Université Henri Poincaré-Nancy I, Vandoeuvre-lès-Nancy, France. |
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Abstract: | The purpose of this work was to study some aspects of bile salt toxicity towards bifidobacteria. A strain (Bifidobacterium coryneforme ATCC 25911) was selected for its lack of conjugated bile salt hydrolase activity (CBSH-), and was used with three deconjugating strains (CBSH+), for study of their growth and viability in the presence of two dihydroxylated conjugated bile salts (tauro- and glyco-deoxycholic acids). The presence of the glycoconjugate induced a more significant growth inhibition for the four strains than the tauroconjugate. The viability of the strains was measured at several pH levels. Glycodeoxycholic acid, but not taurodeoxycholic acid, exerted a lethal effect, which increased at low pH. This phenomenon was more pronounced for the CBSH- strain. We explain some of these results using an hypothesis based on the consequence of dissociation of conjugated and deconjugated bile salts, and the value of their pKa. |
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