Effects of nanoplastics on the gut microbiota of Pacific white shrimp <i>Litopenaeus vannamei</i>

Nanoplastics (NPs) are an abundant, long-lasting, and widespread type of environmental pollution that is of increasing concern because of the serious threats they might pose to ecosystems and species. Identifying the ecological effects of plastic pollution requires understanding the effects of NPs on aquatic organisms. Here, we used the Pacific white shrimp (<i>Litopenaeus vannamei</i>) as a model species to investigate whether ingestion of polystyrene NPs affects gut microbes and leads to metabolic changes in <i>L. vannamei</i>. The abundance of Proteobacteria increased and that of Bacteroidota decreased after NPs treatment. Specifically, <i>Vibrio</i> spp., <i>photobacterium</i> spp., <i>Xanthomarina</i> spp., and <i>Acinetobacter</i> spp. increased in abundance, whereas <i>Sulfitobacter</i> spp. and <i>Pseudoalteromonas</i> spp. decreased. Histological observations showed that <i>L. vannamei</i> exposed to NP displayed a significantly lower intestinal fold height and damaged intestinal structures compared with the control group. Exposure to NPs also stimulated alkaline phosphatase, lysozyme, and acid phosphatase activity, resulting in an immune response in <i>L. vannamei</i>. In addition, the content of triglycerides, total cholesterol, and glucose were significantly altered after NP exposure. These results provided significant ecotoxicological data that can be used to better understand the biological fate and effects of NPs in <i>L. vannamei</i>.