Characterization of Skin Symbiotic Bacteria of Sympatric Amphibians in Southeastern China

The fungal infection called chytridiomycosis,caused by Batrachochytrium dendrobatidis(Bd),has given rise to dramatic declines or extinctions of many amphibian species around the world;however,in Asia,this disease has shown a low zoospore load or scant mortality.One potential reason for this may be that certain unique community structures of amphibian skin symbiosis contribute to the outcome of the disease;nevertheless,we know very little about the microbiota in this region. In this study,we used skin swabs of five sympatric amphibian species that have various habitat preferences in Lishui,Zhejiang Province,a place in southeastern China,to explore the skin bacterial communities by using 16 S rRNA amplicon sequencing.We detected a total of 1020 OTUs,belonging to 17 phyla,among which Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes dominated all five host species.Enterobacteriaceae and Exiguobacteraceae and the genera Escherichia and Exiguobacterium belonging to these two families were identified as the most abundant taxa on our focal species.The alpha diversity was significantly lower on the terrestrial species,and also the highly enriched Proteobacteria was found on the terrestrial species,Rana zhenhaiensis,whereas Actinobacteria,Bacteroidetes,Cyanobacteria and Firmicutes were more abundant on aquatic species than on the terrestrial species.Our results suggest that both host species and habitat sites are important factors driving skin microbial diversity and composition and that amphibians in China may harbour unique skin bacterial communities.This study helps elucidate amphibian skin microbial ecology,and with further efforts,the specific mechanism of the interaction between Bd and host amphibians in China could be elucidated.