Hexavalent chromium exposure disrupts gut microbial structure and metabolic function in broiler chickens

Hexavalent chromium (Cr(VI)) is a pervasive environmental contaminant with well-documented toxicity, yet its impact on the gut microbiome remains poorly understood. This study investigated the effects of chronic dietary Cr(VI) exposure (37 mg/kg feed for 40 days) on the gut microbiota of broiler chickens using 16S rDNA sequencing and bioinformatic analysis. While alpha diversity remained unchanged, significant shifts in beta diversity indicated substantial structural reorganization of microbial communities. Taxonomic analysis revealed a decrease in Firmicutes and an increase in Proteobacteria and Cyanobacteria at the phylum level, along with genus-level alterations including enrichment of Romboutsia and depletion of Enterococcus. Functional prediction via PICRUSt2 further indicated disruptions in key metabolic pathways, particularly the phosphotransferase system (PTS), galactose metabolism, and propanoate metabolism. These findings elucidate a novel mechanism through which chromium exposure may induce toxicity, via disruption of gut microbial structure and function, and underscore the importance of the gut microbiome in mediating chemical toxicity, providing new insights for assessing ecological and health risks of heavy metal exposure.