Gut microbiota promotes cholesterol gallstone formation by modulating bile acid composition and biliary cholesterol secretion.

Cholesterol gallstone disease is a worldwide common disease. Cholesterol supersaturation in gallbladder bile is the prerequisite for its pathogenesis, while the mechanism is not completely understood. In this study, we find enrichment of gut microbiota (especially Desulfovibrionales) in patients with gallstone disease. Fecal transplantation of gut microbiota from gallstone patients to gallstone-resistant strain of mice can induce gallstone formation. Carrying Desulfovibrionales is associated with enhanced cecal secondary bile acids production and increase of bile acid hydrophobicity facilitating intestinal cholesterol absorption. Meanwhile, the metabolic product of Desulfovibrionales, H2S increase and is shown to induce hepatic FXR and inhibit CYP7A1 expression. Mice carrying Desulfovibrionales present induction of hepatic expression of cholesterol transporters Abcg5/g8 to promote biliary secretion of cholesterol as well. Our study demonstrates the role of gut microbiota, Desulfovibrionales, as an environmental regulator contributing to gallstone formation through its influence on bile acid and cholesterol metabolism.

Sulphate-reducing bacterial community structure from produced water of the Periquito and Galo de Campina onshore oilfields in Brazil.

Sulphate-reducing bacteria (SRB) cause fouling, souring, corrosion and produce H2S during oil and gas production. Produced water obtained from Periquito (PQO) and Galo de Campina (GC) onshore oilfields in Brazil was investigated for SRB. Produced water with Postgate B, Postgate C and Baars media was incubated anaerobically for 20 days. DNA was extracted, 16S rDNA PCR amplified and fragments were sequenced using Illumina TruSeq. 4.2 million sequence reads were analysed and deposited at NCBI SAR accession number SRP149784. No significant differences in microbial community composition could be attributed to the different media but significant differences in the SRB were observed between the two oil fields. The dominant bacterial orders detected from both oilfields were Desulfovibrionales, Pseudomonadales and Enterobacteriales. The genus Pseudomonas was found predominantly in the GC oilfield and Pleomorphominas and Shewanella were features of the PQO oilfield. 11% and 7.6% of the sequences at GC and PQO were not classified at the genus level but could be partially identified at the order level. Relative abundances changed for Desulfovibrio from 29.8% at PQO to 16.1% at GC. Clostridium varied from 2.8% at PQO and 2.4% at GC. These data provide the first description of SRB from onshore produced water in Brazil and reinforce the importance of Desulfovibrionales, Pseudomonadales, and Enterobacteriales in produced water globally. Identifying potentially harmful microbes is an important first step in developing microbial solutions that prevent their proliferation.

Nickel complexation as an innovative approach for nickel-cobalt selective recovery using sulfate-reducing bacteria.

This study evaluated the differences in nickel (Ni) and cobalt (Co) solubility in the presence of sulfate reducing bacteria (SRB) to evaluate the feasibility of selective recovery of both metals from mine-impacted waters. A series of sulfate reducing activity tests with Ni, Co and both metals showed that up to 99 % Ni remained soluble despite the availability of sulfide for precipitation, while Co sulfide precipitation always occurred (over 84.5 %). The characterization of proteins in the liquid phase of the experiments revealed that some proteins were only produced in the experiments where Ni displayed higher solubility, suggesting their involvement in metal complexation. Some functions of these proteins included maintaining Ni homeostasis, acting as metalloenzymes and containing Ni-binding ligands. Desulfomicrobium baculatum, Stenotrophomonas maltophilia, and Desulfovibrio magneticus, were the main responsible species producing these proteins.

Proinflammatory Sulfur-Reducing Bacteria Are More Abundant in Colonic Biopsies of Patients with Microscopic Colitis Compared to Healthy Controls.

BACKGROUND: Microscopic colitis (MC), a subtype of inflammatory bowel disease, is a chronic condition of unknown etiology. Recent evidence has linked MC with intriguing changes in the stool microbiota, which may be linked to disease pathogenesis. The composition of the mucosal microbiome in patients with MC remains unclear. METHODS: We performed a cross-sectional study comparing colonic tissue samples from patients with MC to those of healthy controls at the Michael E. DeBakey VA Medical Center. We included adults older than 18 who underwent a colonoscopy with biopsies to evaluate chronic diarrhea. Cases were defined by histology consistent with MC and controls by the absence of histologic disease. We conducted structured chart review to exclude other gastrointestinal diseases and obtain demographic (age, sex, race) and clinical (duration of symptoms and concurrent medications) information for cases and controls. We extracted bacterial DNA from formalin-fixed paraffin-embedded tissue samples and sequenced the v4 region of the 16S rRNA gene. Operational taxonomic unit (OTU) clustering was performed using UPARSE, and OTUs were assigned using the SILVA database. Statistical analysis was performed in QIIME and LEfSe. Comparisons with FDR-adjusted p values of less than 0.05 were considered statistically significant. RESULTS: We included 20 MC patients and 20 controls with mean ages of 62 and 54, respectively. Most cases were White (95%), 60% had symptoms for greater than 12 months, and 50% were taking PPIs and NSAIDs at the time of their diagnosis. Compared to controls, MC patients had a significant increase in the proinflammatory sulfur-reducing bacterial family Desulfovibrionales. The Coriobacteriaceae family, abundant in the healthy gut, was significantly decreased in MC cases. There was also an increase in the genus Actinomyces in MC patients on PPI and an increase in the class Bacilli among those taking NSAIDs. DISCUSSION: Patients with MC have an increase in the proinflammatory family Desulfovibrionales. Actinomyces and Bacilli were associated with medications (PPI and NSAID) known to increase the risk of MC. Our findings may have important implications for understanding the pathogenesis of MC.