Microbial dysbiosis induced in Cyprinus carpio by tetrabromobisphenol A exposure: Mediation through gut barrier impairment and oxidative stress

The frequent detection of Tetrabromobisphenol A (TBBPA) in environmental media has elicited considerable scientific concern. The ecotoxicological impacts of TBBPA on intestinal health in the common carp (Cyprinus carpio) were systematically investigated through integrated histopathological, biochemical, and metagenomic analyses. Fish were exposed to environmentally relevant TBBPA concentrations (0, 0.005, 0.05, and 0.5 mg/L) for a 14-day duration. Dose-dependent intestinal damage was induced by TBBPA exposure, manifested as villus fusion and atrophy, oxidative stress (diminished SOD/CAT activities and elevated MDA levels), and downregulated expression of tight junction proteins (ZO-1, Claudin-3, Occludin). This collectively compromised barrier integrity and triggered pro-inflammatory cytokine upregulation of TNF-α alongside anti-inflammatory IL-10 suppression. Significant intestinal microbial dysbiosis was detected via 16S rRNA sequencing. Alpha diversity indices were reduced at low concentrations (0.005 mg/L) of TBBPA but elevated at higher concentrations (0.05–0.5 mg/L). TBBPA exposure induced gut microbiota perturbations, characterized by depletion of beneficial taxa (Cetobacterium) and enrichment of opportunistic pathogens (Legionella and Thermomonas). Functional prediction analyses indicated that these microbial alterations may influence carbohydrate metabolism, and vitamin biosynthesis within the intestinal tract of common carp. Collectively, these findings demonstrated that TBBPA disrupted intestinal health via synergistic mechanisms involving oxidative stress, histopathological damage, and microbiota-mediated dysregulation. This investigation addresses a critical knowledge gap regarding the impacts of TBBPA on fish gut microbiota, while providing provided a reference for assessing the potential ecological risks of TBBPA in the environment.