Actinobacterial community in Shuanghe Cave using culture-dependent and -independent approaches.

Karst caves, considering to be the "arks" of biodiversity, often contain high levels of endemism. In the present study, the actinobacterial community in Shuanghe Cave, the longest cave in Asia, was analyzed for the first-time using culture-dependent and -independent (16S rRNA amplicon sequencing) approaches. The amplicon sequencing analysis revealed a broad taxonomic diversity in Shuanghe Cave, including 19 phyla (predominantly Actinobacteria) and 264 different genera. While the culture-dependent method got the unrepresentative but supplemental result, a total of 239 actinomycetes were isolated and were identified to seven genera based on culture features and 16S rRNA tests. Among the three habitats (soil, rock soil, and bat guano), the dominant phyla did not differ significantly, while the dominant genus community varied among different habitats, and the richness in soil and rock soil samples was higher than that in bat guano. Furthermore, 16 isolate strains showed antimicrobial activity, especially, the strain S142 (Streptomyces badius) and S761 (Actinoplanes friuliensis) exhibited the most promising activity against various pathogens. Overall, this work showed the abundant bacterial diversity and the antimicrobial potential of the isolates from the Shuanghe Cave.