The influence of a human-relevant polychlorinated biphenyl mixture on the cecal microbiota in female mice 16S rRNA Sequencing

Polychlorinated biphenyls (PCBs) are hazardous environmental pollutants found in both indoor and outdoor settings and have been shown to impact the cecal microbiome. The MARBLES PCB mixture replicates the relative proportions of the 12 most abundant PCB congeners identified in the serum of pregnant women at higher risk of having a child with a neurodevelopmental disorder. We hypothesized that oral exposure to the MARBLES mixture influences microbial communities based on the local concentrations of PCBs and their metabolites in the gastrointestinal tract. Hybrid 75% C57Bl/6J/25% SVJ129 mice were exposed daily for 7 weeks through peanut butter containing either a sham dose (0 mg/kg/day) or low (0.1 mg/kg/day), medium (1 mg/kg/day), or high (6 mg/kg/day) doses of PCBs. About 20 hours after the final exposure, microbiome composition and PCB metabolite levels were analyzed in the cecal content and further PCB and OH-PCB levels were analyzed in discarded feces. MARBLES exposure altered microbial taxa abundance and predicted functions in the cecal content, and the levels of PCBs and their metabolites correlated with changes in specific microbes. These findings suggest that varying levels of PCBs and their metabolites affect the composition and functional predictions of microbial communities. Further research is needed to determine whether these changes result in negative health outcomes.