Effects of short term lead exposure on gut microbiota and hepatic metabolism in adult zebrafish

Lead (Pb) is one of the most prevalent toxic, nonessential heavy metals that has been associated with a wide range of toxic effects in humans and environmental animals. Here, effects of short time exposure to 10 and 30 μg/L Pb on gut microbiota and hepatic metabolism were analyzed in adult male zebrafish. We observed that both 10 and 30 μg/L Pb increased the volume of mucus in the gut. At phylum level, the abundance of α-Proteobacteria decreased significantly and the abundance of Firmicutes increased significantly in the gut when treated with 30 μg/L Pb for 7 days. In addition, the 16S rRNA gene sequencing for V3-V4 region revealed a significant change in the richness and diversity of gut microbiota in 30 μg/L Pb exposed group. A more depth analysis, at the genus level, discovered that 52 gut microbes identified by operational taxonomic unit analysis were changed significantly in 30 μg/L Pb treated group. Based on GC/MS metabolomics analysis, a total of 41 metabolites were significantly altered in 30 μg/L Pb treatment group. These changed metabolites were mainly associated with the pathways of glucose and lipid metabolism, amino acid metabolism, nucleotide metabolism. In addition, we also confirmed that the transcription of some genes related to glycolysis and lipid metabolism, including Gk, Aco, Acc1, Fas, Apo and Dgat, decreased significantly in the liver of zebrafish when exposed to 30 μg/L Pb for 7 days. Our results observed that Pb could cause gut microbiota dysbiosis and hepatic metabolic disorder in zebrafish.