New Insights into the Effect of Fipronil on the Soil Bacterial Community.

Fipronil is a broad-spectrum insecticide with remarkable efficacy that is widely used to control insect pests around the world. However, its extensive use has led to increasing soil and water contamination. This fact is of concern and makes it necessary to evaluate the risk of undesirable effects on non-target microorganisms, such as the microbial community in water and/or soil. Studies using the metagenomic approach to assess the effects of fipronil on soil microbial communities are scarce. In this context, the present study was conducted to identify microorganisms that can biodegrade fipronil and that could be of great environmental interest. For this purpose, the targeted metabarcoding approach was performed in soil microcosms under two environmental conditions: fipronil exposure and control (without fipronil). After a 35-day soil microcosm period, the 16S ribosomal RNA (rRNA) gene of all samples was sequenced using the ion torrent personal genome machine (PGM) platform. Our study showed the presence of Proteobacteria, Actinobacteria, and Firmicutes in all of the samples; however, the presence of fipronil in the soil samples resulted in a significant increase in the concentration of bacteria from these phyla. The statistical results indicate that some bacterial genera benefited from soil exposure to fipronil, as in the case of bacteria from the genus Thalassobacillus, while others were affected, as in the case of bacteria from the genus Streptomyces. Overall, the results of this study provide a potential contribution of fipronil-degrading bacteria.

Tributyrin Attenuates Metabolic and Inflammatory Changes Associated with Obesity through a GPR109A-Dependent Mechanism.

Obesity is linked with altered microbial short-chain fatty acids (SCFAs), which are a signature of gut dysbiosis and inflammation. In the present study, we investigated whether tributyrin, a prodrug of the SCFA butyrate, could improve metabolic and inflammatory profiles in diet-induced obese mice. Mice fed a high-fat diet for eight weeks were treated with tributyrin or placebo for another six weeks. We show that obese mice treated with tributyrin had lower body weight gain and an improved insulin responsiveness and glucose metabolism, partly via reduced hepatic triglycerides content. Additionally, tributyrin induced an anti-inflammatory state in the adipose tissue by reduction of Il-1ß and Tnf-a and increased Il-10, Tregs cells and M2-macrophages. Moreover, improvement in glucose metabolism and reduction of fat inflammatory states associated with tributyrin treatment were dependent on GPR109A activation. Our results indicate that exogenous targeting of SCFA butyrate attenuates metabolic and inflammatory dysfunction, highlighting a potentially novel approach to tackle obesity.

Butyrate Protects Mice from Clostridium difficile-Induced Colitis through an HIF-1-Dependent Mechanism.

Antibiotic-induced dysbiosis is a key factor predisposing intestinal infection by Clostridium difficile. Here, we show that interventions that restore butyrate intestinal levels mitigate clinical and pathological features of C. difficile-induced colitis. Butyrate has no effect on C. difficile colonization or toxin production. However, it attenuates intestinal inflammation and improves intestinal barrier function in infected mice, as shown by reduced intestinal epithelial permeability and bacterial translocation, effects associated with the increased expression of components of intestinal epithelial cell tight junctions. Activation of the transcription factor HIF-1 in intestinal epithelial cells exerts a protective effect in C. difficile-induced colitis, and it is required for butyrate effects. We conclude that butyrate protects intestinal epithelial cells from damage caused by C. difficile toxins via the stabilization of HIF-1, mitigating local inflammatory response and systemic consequences of the infection.