Deconjugation and bile salts hydrolase activity by Bifidobacterium strains with acquired resistance to bile

Deconjugation by bile salts hydrolases in probiotics has been related to reduction of serum cholesterol levels in mammals. We compared the susceptibility to conjugated primary (glycocholate and taurocholate) and secondary (glycodeoxycholate and taurodeoxycholate) salts and the level of hydrolase activity of Bifidobacterium strains with acquired resistance to bile and of their more sensitive original strains. Minimum inhibitory concentrations against conjugated salts of the resistant strains were higher than that of the corresponding originals. None of the strains displayed deconjugation against primary salts, whereas most of them deconjugated secondary salts. Salts of cholic acid were more toxic than that of deoxycholic acid. Derivatives showed higher hydrolase activity than their originals. These results suggested a relationship between bile resistance and deconjugation. Finally, the resistance of bifidobacteria against glycodeoxycholate increased in the presence of maltose and cellobiose as compared with glucose, which could be related to a more efficient energy procurement from disaccharides. (c) 2005 Elsevier Ltd. All rights reserved.