Biological toxicity of sulfamethoxazole in aquatic ecosystem on adult zebrafish (Danio rerio)

Abstract

Abstract The pollution of antibiotics in the water has also become a hot topic in recent years, especially the pollution of sulfonamide antibiotics, which seriously affects the development and growth of aquatic organisms. This study evaluated the impacts of sulfamethoxazole (SMX) on antioxidant, immune, histopathological dynamic changes, and gut microbiota of zebrafish. SMX was carried out five groups: 0 (C), 3 mg/L (T3), 6 mg/L (T6), 12 mg/L (T12), and 24 mg/L (T24), with 5 replicates per group for an 8-weeks chronic toxicity test. It was found that SMX is considered to have low toxicity to adult zebrafish. SMX with the concentration not higher than 24 mg/L has no obvious inhibitory effect on the growth of fish. Under different concentrations of SMX stress, oxidative damage and immune system disorder were caused to the liver and gill, with the 12 and 24 mg/L concentration being the most significant. At the same time, it also causes varying degrees of pathological changes in both intestinal and liver tissues. As the concentration of SMX increases, the composition and abundance of the gut microbiota in zebrafish significantly decrease.