Ecotoxicological impacts of polystyrene microplastics on rainbow trout: A multidisciplinary analysis of gut microbiota dysbiosis, oxidative stress, and cellular senescence for environmental risk assessment

Microplastic (MP) pollution poses a severe threat to aquatic organisms. This study employed multiple approaches, including, gut microbiota profiling, metabolomics, and transcriptomics, to investigate the effects of MPs exposure on intestinal health of rainbow trout and its potential mechanisms. The results showed that MP exposure significantly reduced the activities of antioxidant enzymes (SOD, CAT) while increasing oxidative stress markers (MDA, LPS), indicating compromised intestinal antioxidant defense and aggravated inflammatory responses. Gut microbiota analysis revealed significant alterations in microbial composition, with decreased species richness and altered abundance of key bacterial genera potentially affecting immune function and disease resistance. Metabolomics and transcriptomics analyses identified significantly altered metabolic pathways associated with oxidative stress, apoptosis, and cell cycle regulation, particularly affecting glutathione metabolism and FoxO signaling. These molecular changes were closely correlated with gut microbiota alterations, suggesting that microplastic might affect host physiology by modulating the microbial community. This study demonstrates the adverse effects of microplastic on intestinal health of rainbow trout, highlighting the necessity of implementing measures to mitigate microplastic pollution in aquatic environments.