Toxic effects of chronic Cd exposure on Litopenaeus vannamei based on joint analysis of gut microbiome and metabolomics

The problem of Cd pollution has attracted much attention. Cd stress can inhibit the growth of shrimp and cause serious tissue damage, which is not conducive to the healthy development of shrimp culture industry, and even threaten human food safety. We studied the effects of chronic exposure to different concentrations of Cd on growth performance, tissue enrichment, intestinal microbiology and metabonomics of Penaeus vannamei. The results showed that the growth performance of shrimp was negatively correlated with the concentration of Cd chronic exposure, and the concentration-effect relationship of Cd accumulation in Gill was significant, but the hepatopancreas and intestine only showed a concentration-effect relationship in low concentration (75) and medium concentration (150) exposure. Intestinal microorganisms changed significantly after chronic exposure to Cd. Under high concentration (300) chronic stress, the relative abundance of Vibrio and Motilimonas decreased, while Donghicola, Maribacter and Bacteroides increased significantly. Chronic exposure to Cd also interfered with the intestinal metabolism of shrimp, especially amino acid metabolism. In addition, after high concentration exposure, some metabolites related to growth promotion, antioxidation and intestinal barrier repair were positively correlated with Proteobacteria abundance, but negatively correlated with Bacteroidota. It is suggested that Cd exposure may induce diseased bacteria to participate in the reduction of some metabolites against Cd toxicity, while beneficial bacteria may have the potential to alleviate Cd toxicity.