Adaptive gut microbiota dysbiosis coupled with altered fatty acid metabolism in apple snails (Pomacea canaliculata): A potential strategy against polystyrene microplastic stress.

Microplastic (MP) pollution is a growing concern in aquatic ecosystems, and it can be accumulated within aquatic organisms, but the impact on the physiological status and gut microbiota of freshwater gastropods remains insufficiently understood. This study investigates the impact of polystyrene microplastic (PS) on the gut microbiota and metabolomic of apple snails (Pomacea canaliculata) following a 21-day exposure at three concentrations (1, 10, and 50 mg/L). Results showed that high PS concentrations significantly reduced food intake and weight gain while induced oxidative stress in intestinal tissues. High-throughput sequencing revealed substantial gut microbiota dysbiosis, with a decline in immune-bacteria, such as Bacteroides and Lactococcus, alongside an enrichment of Chlorobium, suggesting adaptive gut microbiota dysbiosis to PS exposure. Metabolomic analysis further identified significant disruptions in fatty acid metabolism, with altered levels of key metabolites such as palmitic acid and capric acid; meanwhile, a significant positive correlation between the long-chain fatty acids (LCFAs) and PS concentration was observed, which would affect the snail's energy balance and physiological functions. These findings highlighted the ecological risks of MPs pollution in freshwater environments and underscore the need for long term studies to evaluate chronic toxicity and potential adaptation mechanisms in aquatic organisms.