Molecular cloning and characterization of bile salt hydrolase in Lactobacillus casei Zhang

Abstract

Bile salt hydrolase (BSH) is one of the genes relevant to bile tolerance. Biochemical assay showed that Lactobacillus casei Zhang was able to deconjugate sodium taurocholate during growth. To explore the possible relationship between BSH activity and bile tolerant ability, we cloned and determined full-length DNA sequence of the BSH gene in L. casei Zhang, and monitored its expression pattern under the stress of bile salts. The DNA sequence consists of 1181 nucleotides; the putative protein includes 338 amino acids. The sequences alignment and homology studies illustrated a great diversity between species. Further real-time PCR analysis revealed that expression of the BSH gene was up-regulated when there presented bile salts in the growth medium.