The effect of fluorine exposure on morphological indicators and intestinal microbial community in Bufo gargarizans tadpoles

Abstract In this study, Bufo gargarizans ( B. gargarizans ) tadpoles were exposed to different fluorine concentrations (0, 0.5, 5 and 50 mg/L NaF) from the Gosner stage 26 to 38. We evaluated effects of fluorine exposure on morphological indicators, gut and intestinal microbiota in B. gargarizans tadpoles. Our results detected that B. gargarizans tadpoles exposure to 5 and 50 mg/L NaF significantly declined the total body length and changed the intestinal morphology. Furthermore, body weight of B. gargarizans tadpoles prominently decreased in 0.5, 5 and 50 mg/L NaF groups. In addition, high-throughput sequencing analysis showed that the diversity and composition of intestinal microbiota in B. gargarizans tadpoles differed among the control and treatment groups. At the phylum level, Proteobacteria increased significantly while Fusobacteria decreased significantly in fluorine exposure groups. At the genus level, the abundant of Raoultella , Shewanella and Escherichia-Shigella were increased in fluorine exposure groups, while Cetobacterium was declined. Also, functional prediction analysis of intestinal microbiota indicated that fluorine exposure obviously altered the metabolism of B. gargarizans tadpoles. Taken together, exposure to fluorine influenced the growth and development of B. gargarizans tadpoles and induced dysbiosis of the intestinal microbiota and metabolic disorder in tadpoles.