Bile salt hydrolase activity is present in nonintestinal lactic acid bacteria at an intermediate level.

Abstract

It is generally considered that bile salt hydrolase (BSH) activity is hardly detected in nonintestinal lactic acid bacteria (LAB). The aim of this study was to investigate the distribution and intensity of BSH activity in LAB isolated from naturally fermented vegetables and milk. A total of 624 lactic acid bacterial strains classified into 6 genera and 50 species were isolated from 144 naturally fermented vegetable samples and 103 naturally fermented milk samples, and their BSH activity was screened by gas chromatography with electron capture detection. The BSH-positive strains were further analyzed quantitatively for their deconjugation ability against six human-conjugated bile salts by HPLC based on the disappearance of the conjugated bile salts from the reaction mixture. The results showed that 39% of the strains possessed BSH activity distributed in 24 lactic acid bacterial species. The strains of the fermented vegetable origin showed a 0.5-fold higher incidence of BSH-positive strains than those of the fermented milk origin, and the lactic acid bacilli exhibited 2.5-fold higher incidence of BSH-positive strains than the lactic acid cocci in general. The strains of the fermented vegetable origin generally had greater bile salt deconjugation ability than those of the fermented milk origin. More than 97% and 93% of the BSH-positive strains exhibited a greater substrate preference for glycoconjugated bile salts than tauroconjugated bile salts and for dihydroxy bile salts than trihydroxy bile salts, respectively. This study demonstrated that BSH activity was also present in nonintestinal LAB.