Concurrent impacts of polystyrene nanoplastic exposure and Aeromonas hydrophila infection on oxidative stress, immune response and intestinal microbiota of grass carp (Ctenopharyngodon idella)

Research has demonstrated that polystyrene nanoplastics (PS-NPs) can have adverse effects on the immune responses of fish. NPs have the potential to increase the likelihood of infections in fish by pathogenic bacteria, such as the opportunistic pathogen Aeromonas hydrophila, potentially increasing the virulence of pathogenic bacteria infections in fish. The concurrent effects of PS-NPs and A. hydrophila on grass carp intestinal tissues were assessed by exposing grass carp to different concentrations of PS-NPs (10 μg/L, 100 μg/L, 1000 μg/L) after infection with A. hydrophila. As the concentration of PS-NPs in the exposure and the duration of A. hydrophila infection both escalated, intestinal tissues showed damage in the form of disordered breakage of intestinal villi, thinning of the intestinal wall, and reduced necrosis of the cells in the annulus muscle layer. The AHS-PS100 group and AHS-PS1000 group exhibited a substantial rise in the function of CAT, SOD, GST, and MPO, as well as increased MDA content and elevated ROS levels (p