A new insight into the physiological role of bile salt hydrolase among intestinal bacteria from the genus Bifidobacterium

PLoS One. 2014 Dec 3;9(12):e114379. doi: 10.1371/journal.pone.0114379. eCollection 2014.

Abstract

This study analyzes the occurrence of bile salt hydrolase in fourteen strains belonging to the genus Bifidobacterium. Deconjugation activity was detected using a plate test, two-step enzymatic reaction and activity staining on a native polyacrylamide gel. Subsequently, bile salt hydrolases from B. pseudocatenulatum and B. longum subsp. suis were purified using a two-step chromatographic procedure. Biochemical characterization of the bile salt hydrolases showed that the purified enzymes hydrolyzed all of the six major human bile salts under the pH and temperature conditions commonly found in the human gastrointestinal tract. Next, the dynamic rheometry was applied to monitor the gelation process of deoxycholic acid under different conditions. The results showed that bile acids displayed aqueous media gelating properties. Finally, gel-forming abilities of bifidobacteria exhibiting bile salt hydrolase activity were analyzed. Our investigations have demonstrated that the release of deconjugated bile acids led to the gelation phenomenon of the enzymatic reaction solution containing purified BSH. The presented results suggest that bile salt hydrolase activity commonly found among intestinal microbiota increases hydrogel-forming abilities of certain bile salts. To our knowledge, this is the first report showing that bile salt hydrolase activity among Bifidobacterium is directly connected with the gelation process of bile salts. In our opinion, if such a phenomenon occurs in physiological conditions of human gut, it may improve bacterial ability to colonize the gastrointestinal tract and their survival in this specific ecological niche.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amidohydrolases / chemistry
  • Amidohydrolases / physiology*
  • Amino Acid Sequence
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / physiology*
  • Bifidobacterium / enzymology*
  • Biocatalysis
  • Deoxycholic Acid / chemistry
  • Humans
  • Hydrogels / chemistry
  • Hydrogen-Ion Concentration
  • Phylogeny
  • Substrate Specificity

Substances

  • Bacterial Proteins
  • Hydrogels
  • Deoxycholic Acid
  • Amidohydrolases
  • choloylglycine hydrolase

Grants and funding

This work was supported by grant DEC-2011/01/N/NZ9/04575 from National Science Centre (http://www.ncn.gov.pl/?language=en) and partially by grant Nr 0195/IP1/2011/71 from Ministry of Science and Higher Education (http://www.nauka.gov.pl/en/). The funding was received by PJ, MP, and ZT. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.