A New Insight into the Physiological Role of Bile Salt Hydrolase among Intestinal Bacteria from the Genus Bifidobacterium

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.

Evaluation of the prebiotic potential of five kiwifruit cultivars after simulated gastrointestinal digestion and fermentation with human faecal bacteria

“…Of the Firmicutes, there was a significant decrease in Faecalibacterium after fermentation as compared to the faeces inoculum, and this has been attributed to sensitivity of Faecalibacterium to the bile salts in the culture medium (Long et al, 2015). The abundance of Faecalibacterium was partially restored in the presence of kiwifruit, which may be attributed to an increase in bacteria that metabolise bile, such as Ruminococcaceae and Bifidobacterium (Jarocki et al, 2014;Labbe et al, 2014). Different groups of bacteria occupy different niches in the intestine, based on the availability of substrates, with the mucus-adherent butyrate producers increasing in the distal colon, which is comparatively energy poor (Donaldson et al, 2016).…”

Interactions between bile salts, gut microbiota, and hepatic innate immunity

“…These enzymes are widely distributed among commensal bacteria, although the diversity is larger in Gram‐positive genera including Lactobacillus , Enterococcus , Clostridium , and Bifidobacterium . In contrast, Bacteroides is the only Gram‐negative genus with reported bile salt hydrolase activity . The further processing of taurine has been studied in detail in Bilophila wadsworthia .…”

Mathematically modelling the dynamics of cholesterol metabolism and ageing

“…Although preferentially hydrolysing glyco-conjugated bile acids, both glyco-and tauroconjugated bile acids can be converted to unconjugated bile acids whilst in the intestinal lumen by the hydrolysis of the amine bond, and removal of glycine or taurine by bacterial bile salt hydrolase (BSH) (Jarocki et al, 2014). Certain intestinal microflora have the ability to produce BSH, but Lactobacillus species are responsible for 86% of the BSH activity in the ileum, and 74% in the caecum (Tannock et al, 1989).…”

“…In recent years however, several groups have adopted a systems level approach to investigating lipid metabolism Mooney et al, 2016). The majority of these models have centred on specific metabolic processes, including those directed at lipoprotein metabolism (Hubner et al, 2008;Shorten and Upreti, 2005;Sips et al, 2014), cholesterol biosynthesis (Bhattacharya et al, 2014;Kervizic and Corcos, 2008;Mazein et al, 2013;Watterson et al, 2013), reverse cholesterol transport (Lu et al, 2014), adipocyte metabolism (Micheloni et al, 2015), hepatocyte metabolism (Jerby et al, 2010), cholesterol regulatory enzymes (Chapman et al, 2010), whole-body plasma cholesterol metabolism (van de Pas et al, 2012) and enterohepatic circulation of bile acids (Mishra et al, 2014). These models all have noteworthy features and have added to our understanding of lipid metabolism.…”