Bile salt toxicity to some bifidobacteria strains: role of conjugated bile salt hydrolase and pH.
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.
Grill
J P
JP
Laboratoire de Biochimie des Bactéries Gram+, Université Henri Poincaré-Nancy I, Vandoeuvre-lès-Nancy, France.
Perrin
S
S
Schneider
F
F
D000581:Amidohydrolases / Q000378:metabolism*; D001644:Bifidobacterium / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development; D003470:Culture Media; D006002:Glycodeoxycholic Acid / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D013657:Taurodeoxycholic Acid / Q000494:pharmacology*
D003470:Culture Media; D006002:Glycodeoxycholic Acid; D013657:Taurodeoxycholic Acid; D000581:Amidohydrolases; C023154:choloylglycine hydrolase