Genetic analysis of a bile salt hydrolase in Bifidobacterium animalis subsp. lactis KL612.
OBJECTIVE
To clone, sequence and characterize a new bile salt hydrolase from a bile tolerant strain of Bifidobacterium animalis ssp. lactis KL612, and further analysis of the bsh promoter and an operon-like structure containing the bsh gene in the genus Bifidobacterium.


RESULTS
A new type of bile salt hydrolase from a bile tolerant strain of Bifidobacterium was cloned, completely sequenced and characterized. The putative bsh promoter sequence was analysed by primer extension to determine the transcriptional start point by applying the genomic walking-PCR, an operon-like structure containing the bsh gene and two more open reading frames located within a complete set ranging from a promoter to a transcription terminator sequence is reported for the first time in the genus Bifidobacterium. The polycistronic bsh transcript was revealed by reverse transcriptase-PCR (RT-PCR) as well as by Northern hybridization.


CONCLUSIONS
Most of bile tolerant strains of bifidobacteria showed a similar genetic organization around the bsh gene. This finding suggests that bile tolerance of those strains is possibly because of the bile salt hydrolase and some transporter proteins, which are functionally related to each other to respond efficiently to the stress from bile salts.


CONCLUSIONS
Knowledge gained through BSH research would provide further insight into the survival of probiotics in the gastrointestinal tract and some physiological functions of this enzyme in relation to the host as well as the enzyme-producing bacteria.
Kim
G-B
GB
Department of Food Science and Agricultural Chemistry, McGill University, Montreal, Quebec, Canada.
Lee
B H
BH
D000581:Amidohydrolases / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D001644:Bifidobacterium / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D001647:Bile Acids and Salts / Q000378:metabolism; D015152:Blotting, Northern; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D009876:Operon; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
D001647:Bile Acids and Salts; D000581:Amidohydrolases; C023154:choloylglycine hydrolase