Effects of cadmium on intestinal histology and microbiota in freshwater crayfish (Procambarus clarkii)

In this study, Procambarus clarkii (P. clarkii) were exposed to different concentrations (0, 2, 5 and 10 mg/L) of cadmium (Cd). We studied the effects of Cd exposure on intestinal histology and microbiota in P. clarkii. The results demonstrated that exposure to Cd caused histological alterations in the intestines of P. clarkii. Meanwhile, high-throughput sequencing analysis revealed that Cd exposure could alter the richness, diversity, and composition of intestinal microbiota in P. clarkii. At the phylum level, the relative abundances of the prevalent phyla Firmicutes, Proteobacteria, Bacteroidetes, Fusobacteria, and Actinobacteria changed significantly after exposure to Cd. At the genus level, the most prevalent genera with significant difference in relative abundance were Bacteroides, Clostridium XlVb, Hafnia, Buttiauxella, Shewanella, Anaerorhabdus, Alistipes, Arcobacter, Azoarcus, Chryseobacterium, and so on. Furthermore, functional prediction analysis of intestinal microbial communities showed that Cd exposure could significantly alter the pathways related to metabolism, diseases, cellular processes, and so on. Taken together, exposure to Cd could induce intestinal histological damage and affect intestinal microbiota composition and functions of P. clarkii. Our study can be an important step toward a better understanding of the toxic effects of Cd on aquatic crustaceans.