Imazalil exposure induces gut microbiota dysbiosis and hepatic metabolism disorder in zebrafish

The fungicide imazalil (IMZ) is used extensively to preserve freshness, prevent decay and control fungal infections in fruits, vegetables or other plants. Recently, some studies have reported that the real in aquatic systems have reached very high levels. Here, male adult zebrafish were exposed to 100 and 1000 μg/L IMZ for 1, 7, 21 days, and the gut microbiota and hepatic metabolism were evaluated. Exposure to a high concentration of IMZ for 21 days decreased mucin secretion in the gut. Sequencing of the V3-V4 region of the bacterial 16S rRNA gene revealed a significant increase in the diversity of gut microbiota in male zebrafish. At the phylum level, the composition of Proteobacteria and Bacteroidetes was decreased, while those Fusobacteria and Firmicutes increased in the gut after exposure to 1000 μg/L IMZ for 21 days. At the genus level, 29 species of microorganisms were significantly changed after IMZ exposure. Based on GC/MS metabolomics analysis, 101 metabolites were observably significantly altered in the 1000 μg/L IMZ-treatment group. These changed metabolites were mainly associated with the pathway of glycolysis, amino acid metabolism, and lipid metabolism. In addition, the transcription of some genes related to glycolysis and lipid metabolism, including Aco, Cpt1, Acc1, Srebp1a and Fas, was decreased significantly in the liver of zebrafish when exposed to 100 and 1000 μg/L IMZ for 7 or 21 days. These results indicated that exposure to IMZ could cause gut microbiota dysbiosis and metabolic disorders in adult zebrafish.