Search Results (9)

Background: Bee pollen is a uniquely complete nutritional product that has shown promise in alleviating obesity. While existing research has largely focused on the role of gut microbiota in obesity, the mechanisms by which bee pollen influences bile acid (BA) metabolism via microbial regulation remain poorly understood. Methods: This study hypothesized that Schisandra chinensis bee pollen extract (SCPE) could mitigate high-fat diet (HFD)-induced obesity by regulating BA metabolism. Results: In a 12-week animal experiment, SCPE supplementation significantly reduced body weight gain, lipid accumulation, and adipocyte hypertrophy, while improving insulin sensitivity and relieving hepatic oxidative stress. These benefits were attributed to an increased relative abundance of bile salt hydrolase (BSH)-producing microbes, including Bacteroides, Lachnospiraceae NK4A136 group, and Akkermansia, which modulated BA metabolism by improving the expression of BA metabolism-related genes and reducing the concentrations of various types of BAs. Conclusions: These findings provide new insights into the mechanism by which SCPE alleviates obesity through the gut microbiota-BA axis and support the potential of bee pollen as a functional food for obesity management. Full article

Background: Obesity is a highly prevalent chronic disease characterized by excessive weight gain and fat accumulation. There is growing evidence that Lactiplantibacillus plantarum strains with bile salt hydrolase (BSH) activity are effective in preventing and alleviating obesity. Methods: Initially, we screened bacterial strains with high hydrolytic activity against glycochenodeoxycholic acid (GDCA), and constructed an isogenic bsh1 knockout mutant. Subsequently, male C57BL/6J mice fed a high-fat diet (HFD) were randomly assigned to receive daily gavage of either the wild-type Lp20 (Lp20-WT) or the bsh1-deficient mutant (Lp20-Δbsh1) for 8 weeks. Serum cholesterol levels and histopathological changes in liver sections were monitored. Hepatic gene expression was quantified by RT-qPCR, and fecal bacterial communities were analyzed via 16S rRNA gene sequencing. These comprehensive assessments aimed to evaluate metabolic improvements and uncover the potential mechanisms behind the observed effects. Results:L. plantarum Lp20 hydrolyzed 91.62% of GDCA, exhibiting the highest bile-salt hydrolase (BSH) activity among tested isolates. Whole-genome sequencing and in-silico analyses mapped this activity to bsh1; gene deletion of bsh1 confirmed the role of bsh1 in GDCA hydrolysis. Daily gavage of the wild-type strain (Lp20-WT) to diet-induced obese mice markedly attenuated weight gain, reduced inguinal white adipose tissue and mesenteric fat mass, and lowered serum TC and LDL-C by 20.8% and 33.3%, respectively, while decreasing ALT and AST levels and reversing hepatic steatosis. In contrast, the bsh1-null mutant (Lp20-Δbsh1) failed to elicit any measurable metabolic benefit. Mechanistically, Lp20-WT upregulated rate-limiting bile-acid synthetic enzymes CYP7A1 and CYP27A1, thereby accelerating the catabolism of cholesterol into bile acids. Concurrently, it activated hepatic TGR5 and FXR signaling axes to modulate hepatic metabolism. Moreover, Lp20-WT restructured the gut microbiota by notably enhancing the abundance of beneficial bacteria such as norank_f__Muribaculaceae, Akkermansia, and Alistipes, while reducing the abundance of potentially harmful taxa, including norank_f__Desulfovibrionaceae, Dubosiella, and Mucispirillum. Conclusions: This study provides direct evidence of BSH’s anti-obesity effects through gene deletion. Specifically, BSH lowers cholesterol by modulating hepatic bile-acid metabolism-related gene expression and altering the gut microbiota composition. However, the study is limited by a small sample size (n = 6), the use of male mice only, and its preclinical stage, indicating a need for further validation across diverse strains and human populations. Full article

Background: Bile salt hydrolase (BSH) is a key probiotic trait, as it facilitates both host metabolism and bacterial survival into the gastrointestinal tract (GIT), through bile acid (BA) deconjugation, keeping intestinal homeostasis. Objectives: The present study aims to investigate the viability of the Lacticaseibacillus rhamnosus VB4 strain and its effects on bile acid deconjugation during the gastrointestinal tract (GIT) passage, under a fed condition, using the in vitro SHIME^® (Simulator of the Human Intestinal Microbial Ecosystem) model. Methods: Gastric, small intestinal and colonic fractions were monitored and a fecal slurry from a healthy donor was inoculated into the colonic compartment to establish the intestinal microbiota. Samples were collected at the end of stomach, duodenum, jejunum, ileum phases, and colon after 0, 16 and 24 h. Strain survival was assessed by culturing method, and bsh gene expression was revealed by quantitative PCR (qPCR). In addition, UHPLC/HR-MS was performed to reveal the hypothetical changes in BAs profile after strain administration. Results: Good survivability of the VB4 strain in the upper GIT was revealed. Furthermore, VB4-inculated sample showed sustained expression of bsh in both the stomach/small intestine and colon fractions at all sampling times. Analysis of the BAs profile shown that the VB4 strain reduced the levels of the main conjugated BAs in the small intestine under fed condition and improved the deconjugation efficiency during colonic transit compared with the control. Conclusions: These findings highlight the survivability of L. rhamnosus VB4 strain inside the gut and its potential as biotherapeutic BAs-mediator candidate, demonstrating that transcriptomic and metabolomic approaches coupled to a dynamic in vitro gut model represent a robust tool for selection of a BSH-positive probiotic candidate. Full article

Background: Berberine has extremely low oral bioavailability, but shows a potent lipid-lowering effect, indicating its potential role in regulating intestinal microbiota, which has not been investigated. Methods: In the present study, five experimental diets, a control diet (Con), a high-lipid diet (HL), and high-lipid·diets·supplemented with an antibiotic cocktail (HLA), berberine (HLB), or both (HLAB) were fed to zebrafish (Danio rerio) for 30 days. Results: The HLB group showed significantly greater weight gain and feed intake than the HLA and other groups, respectively (p < 0.05). Hepatic triglyceride (TG) and total cholesterol (TC) levels, lipogenesis, and proinflammatory cytokine gene expression were significantly upregulated by the high-lipid diet, but significantly downregulated by berberine supplementation. Conversely, the expression levels of intestinal and/or hepatic farnesoid X receptor (fxr), Takeda G protein-coupled receptor 5 (tgr5), lipolysis genes, and zonula occludens 1 (zo1) exhibited the opposite trend. Compared with the HLB group, the HLAB group displayed significantly greater hepatic TG content and proinflammatory cytokine expression, but significantly lower intestinal bile salt hydrolase (BSH) activity and intestinal and/or hepatic fxr and tgr5 expression levels. The HL treatment decreased the abundance of certain probiotic bacteria (e.g., Microbacterium, Cetobacterium, and Gemmobacter) and significantly increased the pathways involved in cytochrome P450, p53 signaling, and ATP-binding cassette (ABC) transporters. The HLB group increased some probiotic bacteria abundance, particularly BSH-producing bacteria (e.g., Escherichia Shigella). Compared with the HLB group, the abundance of BSH-producing bacteria (e.g., Bifidobacterium and Enterococcus) and pathways related to Notch signaling and Wnt signaling were reduced in the HLAB group. Conclusions: This study revealed that berberine’s lipid-lowering and intestine-protective effects are closely related to the intestinal microbiota, especially BSH-producing bacteria. Full article

Bile salt hydrolase (BSH; EC 3.5.1.24) is the microbial enzyme that catalyzes the conversion of primary bile acids (BAs) into secondary ones, promoting microbial adaptation and modulating several host’s biological functions. Probiotics with BSH activity are supposed to survive harsh intestinal conditions and exert a cholesterol-lowering effect. Here, Lacticaseibacillus rhamnosus strains (VB4 and VB1), isolated from the vaginal ecosystem, were submitted to a genomic survey, in vitro BSH activity, and BAs tolerance assay to unravel their probiotic potential as BAs modulators. The draft genomes of Lcb. rhamnosus VB4 and VB1 strains comprised 2769 and 2704 CDSs, respectively. Gene annotation revealed numerous strain-specific genes involved in metabolism and transport, as well as in DNA recombination. Each strain harbors a single bsh gene, encoding a C-N amide hydrolase, which conserved the essential residues required in the BSH core site. According to the results, compared to VB1, the VB4 strain tolerated better BAs stress and was more active in deconjugating BAs. However, BAs stress increased the bsh gene transcription in the VB1 strain but not in the VB4 strain, suggesting a partially nonlinear relationship between BSH activity and gene expression. In conclusion, despite the complexity of the BSH transcriptional system, the results support the VB4 strain as a promising BAs-deconjugating probiotic candidate. Full article

Clostridium perfringens is the main pathogen of chicken necrotic enteritis (NE) causing huge economic losses in the poultry industry. Although dietary secondary bile acid deoxycholic acid (DCA) reduced chicken NE, the accumulation of conjugated tauro-DCA (TDCA) raised concerns regarding DCA efficacy. In this study, we aimed to deconjugate TDCA by bile salt hydrolase (BSH) to increase DCA efficacy against the NE pathogen C. perfringens. Assays were conducted to evaluate the inhibition of C. perfringens growth, hydrogen sulfide (H₂S) production, and virulence gene expression by TDCA and DCA. BSH activity and sequence alignment were conducted to select the bsh gene for cloning. The bsh gene from Bifidobacterium longum was PCR-amplified and cloned into plasmids pET-28a (pET-BSH) and pDR111 (pDR-BSH) for expressing the BSH protein in E. coli BL21 and Bacillus subtilis 168 (B-sub-BSH), respectively. His-tag-purified BSH from BL21 cells was evaluated by SDS-PAGE, Coomassie blue staining, and a Western blot (WB) assays. Secretory BSH from B. subtilis was analyzed by a Dot-Blot. B-sub-BSH was evaluated for the inhibition of C. perfringens growth. C. perfringens growth reached 7.8 log10 CFU/mL after 24 h culture. C. perfringens growth was at 8 vs. 7.4, 7.8 vs. 2.6 and 6 vs. 0 log10 CFU/mL in 0.2, 0.5, and 1 mM TDCA vs. DCA, respectively. Compared to TDCA, DCA reduced C. perfringens H₂S production and the virulence gene expression of asrA1, netB, colA, and virT. BSH activity was observed in Lactobacillus johnsonii and B. longum under anaerobe but not L. johnsonii under 10% CO₂ air. After the sequence alignment of bsh from ten bacteria, bsh from B. longum was selected, cloned into pET-BSH, and sequenced at 951 bp. After pET-BSH was transformed in BL21, BSH expression was assessed around 35 kDa using Coomassie staining and verified for His-tag using WB. After the subcloned bsh and amylase signal peptide sequence was inserted into pDR-BSH, B. subtilis was transformed and named B-sub-BSH. The transformation was evaluated using PCR with B. subtilis around 3 kb and B-sub-BSH around 5 kb. Secretory BSH expressed from B-sub-BSH was determined for His-tag using Dot-Blot. Importantly, C. perfringens growth was reduced greater than 59% log10 CFU/mL in the B-sub-BSH media precultured with 1 vs. 0 mM TDCA. In conclusion, TDCA was less potent than DCA against C. perfringens virulence, and recombinant secretory BSH from B-sub-BSH reduced C. perfringens growth, suggesting a new potential intervention against the pathogen-induced chicken NE. Full article

In the present study, thirty two lactic acid bacteria (LAB) were isolated from fermented Indian herbal medicine. In comparison to other strains, MNL5 had stronger bile salt hydrolase (BSH) and cholesterol-lowering properties. Furthermore, it can withstand the extreme conditions found in the GI tract, due to, e.g., pepsin, bile salts, pancreatin, and acids. Pediococcus acidilactici MNL5 was identified as a probiotic candidate after sequencing the 16S rRNA gene. The antibacterial activity of P. acidilactici MNL5 cell-free supernatants (CFS) against Escherichia coli, Staphylococcus aureus, Helicobacter pylori, Bacillus cereus, and Candida albicans was moderate. A Caenorhabditis elegans experiment was also performed to assess the effectiveness of P. acidilactici MNL5 supplementation to increase life span compared to E. coli supplementation (DAF-2 and LIU1 models) (p < 0.05). An immense reduction of the lipid droplets of C. elegans was identified through a fluorescent microscope. The drastic alteration of the expression of fat genes is related to obesity phenotypes. Hence, several paths are evolutionary for C. elegans; the results of our work highlight the nematode as an important model for obesity. Full article

Lactobacillus gasseri is one of the most likely probiotic candidates among many Lactobacillus species. Although bile salt resistance has been defined as an important criterion for selection of probiotic candidates since it allows probiotic bacteria to survive in the gut, both its capability and its related enzyme, bile salt hydrolase (BSH), in L. gasseri is still largely unknown. Here, we report that the well-known probiotic bacterium L. gasseri JCM1131^T possesses BSH activity and bile salt resistance capability. Indeed, this strain apparently showed BSH activity on the plate assay and highly tolerated the primary bile salts and even taurine-conjugated secondary bile salt. We further isolated a putative BSH enzyme (LagBSH) from strain JCM1131^T and characterized the enzymatic function. The purified LagBSH protein exhibited quite high deconjugation activity for taurocholic acid and taurochenodeoxycholic acid. The lagBSH gene was constitutively expressed in strain JCM1131^T, suggesting that LagBSH likely contributes to bile salt resistance of the strain and may be associated with survival capability of strain JCM1131^T within the human intestine by bile detoxification. Thus, this study first demonstrated the bile salt resistance and its responsible enzyme (BSH) activity in strain JCM1131^T, which further supports the importance of the typical lactic acid bacterium as probiotics. Full article

Oxidative stress occurs when cells are exposed to elevated levels of reactive oxygen species that can damage biological molecules. One bacterial response to oxidative stress involves disulfide bond formation either between protein thiols or between protein thiols and low-molecular-weight (LMW) thiols. Bacillithiol was recently identified as a major low-molecular-weight thiol in Bacillus subtilis and related Firmicutes. Four genes (bshA, bshB1, bshB2, and bshC) are involved in bacillithiol biosynthesis. The bshA and bshB1 genes are part of a seven-gene operon (ypjD), which includes the essential gene cca, encoding CCA-tRNA nucleotidyltransferase. The inclusion of cca in the operon containing bacillithiol biosynthetic genes suggests that the integrity of the 3′ terminus of tRNAs may also be important in oxidative stress. The addition of the 3′ terminal CCA sequence by CCA-tRNA nucleotidyltransferase to give rise to a mature tRNA and functional molecules ready for aminoacylation plays an essential role during translation and expression of the genetic code. Any defects in these processes, such as the accumulation of shorter and defective tRNAs under oxidative stress, might exert a deleterious effect on cells. This review summarizes the physiological link between tRNA^Cys regulation and oxidative stress in Bacillus. Full article