Identification of the role of toxin B in the virulence of Clostridioides difficile based on integrated bioinformatics analyses

Water Level Fluctuations Modulate the Microbiomes Involved in Biogeochemical Cycling in Floodplains

Drastic changes in hydrological conditions within floodplain ecosystems create distinct microbial habitats. However, there remains a lack of exploration regarding the variations in microbial function potentials across the flooding and drought seasons. In this study, metagenomics and environmental analyses were employed in floodplains that experience hydrological variations across four seasons. Analysis of functional gene composition, encompassing nitrogen, carbon, and sulfur metabolisms, revealed apparent differences between the flooding and drought seasons. The primary environmental drivers identified were water level, overlying water depth, submergence time, and temperature. Specific modules, e.g., the hydrolysis of β-1,4-glucosidic bond, denitrification, and dissimilatory/assimilatory nitrate reduction to ammonium, exhibited higher relative abundance in summer compared to winter. It is suggested that cellulose degradation was potentially coupled with nitrate reduction during the flooding season. Phylogenomic analysis of metagenome-assembled genomes (MAGs) unveiled that the Desulfobacterota lineage possessed abundant nitrogen metabolism genes supported by pathway reconstruction. Variation of relative abundance implied its environmental adaptability to both the wet and dry seasons. Furthermore, a novel order was found within Methylomirabilota, containing nitrogen reduction genes in the MAG. Overall, this study highlights the crucial role of hydrological factors in modulating microbial functional diversity and generating genomes with abundant nitrogen metabolism potentials.

Bisphenol A biodegradation differs between mudflat and mangrove forest sediments

Bisphenol A (BPA) is one of the widely detected endocrine disrupting chemicals in coastal sediment. Biodegradation is a vital pathway of BPA elimination in sediment. However, the impact of vegetation on BPA degradation in coastal sediment is still unclear. In this study, the differences of BPA biodegradation and the functional microbial community and metabolic pathway were explored between mangrove forest and mudflat sediments. A nearly complete BPA attenuation was detected in 4 days in mudflat sediment but 8 days in forest sediment. Bacterial abundance varied greatly in different sediment types. Bacterial community structure changed with BPA biodegradation, dependent on sediment type. During the degradation, the proportions of Alphaproteobacteria and Gammaproteobacteria were higher in BPA amended microcosms than in un-amended microcosms. With BPA biodegradation, a substantial increase in Novosphingobium and Croceicoccus occurred in forest sediment and mudflat sediment, respectively. Additionally, two divergent BPA biodegradation pathways were proposed based on functional annotation and KEGG pathway database. The abundance of functional genes also varied with BPA biodegradation, dependent on sediment type. Gene pcaGH decreased, while genes ligK and pcaD increased in both sediment types. Gene pcaB showed a remarkable increase in forest sediment but a decrease in mudflat sediment. Therefore, BPA degradation and the associated microbial community and metabolic pathway differed between mudflat and mangrove forest sediments.

Rhubarb extract relieves constipation by stimulating mucus production in the colon and altering the intestinal flora

BACKGROUND

Constipation, mainly characterized by the difficulty in defecation, is a clinical symptom caused by a variety of factors. It can be manifested as normal or slow colonic transport abnormalities, which can occur alone or concurrently with defecation disorders. As there is not uniform definition and assessment standard, no clear plan could be used for the treatment of constipation. Although rhubarb, a traditional Chinese medicine, plays a therapeutic role in diseases involving constipation symptoms, the detailed mechanism of it in treating constipation remains unclear.

METHODS

A model of constipation-induced by diphenoxylate was prepared. Immunofluorescent staining was used to detect the expression of mucin 2 (MUC2), calnexin and chymase in colon. Western blotting was used to detect changes of tryptase and calnexin in the colon. And real-time polymerase chain reaction (PCR) was utilized to detect the changes of immunoglobulin-binding protein (Bip), X-box binding protein 1 (Xbp1) and C/EBP homologous protein (CHOP) of colonic goblet cells in mRNA levels. ELISA and biochemical kits were utilized to detect the changes of MUC2, Trefoil factor 3 (TFF3), acetylcholine, histamine and C-C motif chemokine ligand 5 (CCL5) in the colon. And the changes of colonic mucosa and intestinal flora of constipation model mice caused by rhubarb extract (RE) were analyzed to identify the mechanism of RE on the treatment of constipation.

RESULTS

RE promotes the secretion of colonic mucus by recruiting mast cells and enhancing the content of histamine and Ach in the mice colon. In the process, RE causes up-regulation of Bip and CHOP mRNA expression and down-regulation of Xbp1 and Xbp1s mRNA expression that induces ER stress of colonic epithelium associated with changes in the intestinal flora diversity and short-chain fatty acids content.

CONCLUSION

RE could relieve constipation by promoting the secretion of colonic mucus via mast cells activation and improving the intestinal microenvironment.