Organophosphate pesticides modulate gut microbiota and influence bile acid metabolism in an in vitro fermentation model

Widely used organophosphate (OP) pesticides are shown to be of acute neurotoxicity; however, OP residues were frequently reported to be present in our living surroundings, posing a risk to human health. In this study, the effects of OP pesticides on gut microbiota mediated bile acid metabolism were investigated using a simple batch fermentation in vitro model, in which mouse fecal samples were incubated with six OPs and a mixture of bile acids. Samples were taken during the 24 h incubation and bile acid profiles were quantified by LC-MS/MS. OP treatment induced microbiota dependent alterations of primary and secondary bile acid levels, including especially substantially increased production of omega-muricholate and decreased levels of beta-muricholate. As a result, phorate led to the most significant effects on the bile acid profile and was selected for further determination of accompanying effects on the bacterial profile by 16S rRNA sequencing. Results showed that richness of the Muribaculaceae spp. significantly decreased after the exposure to phorate. In summary, OP treatment could lead to perturbation of gut microbiota resulting in correlated changes in related bile acid metabolism.