Comparison of the characteristics of intestinal microbiota response in Bufo gargarizans tadpoles: Exposure to the different environmental chemicals (Cu, Cr, Cd and NO 3 -N).

Environmental pollutants could change the intestinal microbiota communities, while data concerning the dynamics of the intestinal microbiota in response to different environmental chemicals in amphibian are lacking. We compared the effects of Cu, Cd, Cr and NO3–N on intestinal microbiota of B. gargarizans tadpoles by using high-throughput 16S rRNA sequencing technology. Our results revealed that responses of intestinal microbiota to three metals and NO3–N showed different characteristics. At the phylum level, the most 100 OTUs were predominantly colonized by Proteobacteria, and meanwhile, expansion of Proteobacteria was observed in Cu 64 μg/L, Cd (100 μg/L and 200 μg/L) and NO3–N100 mg/L treatment groups. In addition, the abundance of Bacteroidetes significantly increased in the gut administrate with Cu, Cd, Cr, NO3–N 20 mg/L exposures, while declined abundance of Fusobacteria was observed in Cu64 μg/L Cd100 μg/L Cd200μg/L-exposed groups. At the genus level, several genera exhibited increased prevalence of abundance such as Shewanella, Azospira and Flavobacterium. The functional prediction revealed that exposures of three metals and NO3–N increase the risks of metabolic disorders and diseases. Our research could be an important step toward an assessment of the ecological risks of different chemicals to aquatic organisms using intestinal microbiota.