The toxic effects of benzalkonium chloride on intestinal health in common carp (Cyprinus carpio L.): Potential role of intestinal microbiota-derived metabolites dysbiosis

Benzalkonium chloride (BAC) is a broad-spectrum antimicrobial disinfectant that commonly used in various products of daily routine. Although the concerns regarding the adverse effects of BAC have been emerged, the potential impacts of BAC on host health remain uncertain. In this study, the toxic potential of environmentally relevant BAC to the intestine of common carp ( Cyprinus carpio L.) was examined. Histopathological results showed that BAC treatment changed intestinal structure and induced intestinal injury in fish. Biochemical analyses indicated that BAC altered the levels of tight junction proteins, inflammatory factors and oxidative stress related indicators. In addition, BAC significantly decreased the activities of lipase and altered the levels of α-amylase. Metagenomics and metabolomics results suggested that BAC exposure induced the dysbiosis of intestinal microbiota and metabolites, significantly altered lipid metabolism. Correlation analysis revealed that Alloprevotella was positively associated the metabolites in glycerophospholipid metabolism and alpha-linolenic acid metabolism, Clostridium_sensu_stricto_7 and Bacteroides were significantly positive correlated with the metabolites in arachidonic acid metabolism, Serratia was significantly correlated with the metabolites in alpha-linolenic acid metabolism, suggesting the dysbiosis of intestinal microbiota-derived lipid metabolism potentially influencing intestinal health. This study affirms that BAC-induced intestinal microbiota-derived lipid metabolism dysbiosis is adverse to intestinal health in aquatic ecosystems, and provides theoretical basis for evaluating the risk of disinfectants application. • The toxic effects of BAC on intestine in common carp were observed. • Oxidative stress and inflammatory response were observed after BAC exposure. • BAC changed the compositions of intestinal microbiota and metabolites. • Lipid metabolism disturbances were specially induced by BAC. • Intestinal microbiota-derived metabolites were traced based on correlation analysis.