Analysis of bacterial communities and exploration of coral pathogenic bacteria in the soft corals from Chuuk, Micronesia

Abstract

Coral-associated microbes play an essential role in maintaining viable coral reefs, which are a crucial niche in marine ecosystems, providing shelter for many marine organisms. In the present study, we employed 16S rRNA next generation sequencing to characterize bacterial community composition of seawater and 2 different corals, Nephthea sp. and Sinularia sp., of Weno, an island in the Federated States of Micronesia (FSM), South Pacific. Bacterial community composition was found to be diverse and species-specific at both the phylum and class level. For both coral species, the majority of bacterial colonization was confined to a single phylum. For Nephthea sp., Proteobacteria (62.33%) was the most abundant phylum, while for Sinularia sp., Spirochaetes (63.22%) was the most predominate. At the class level, Gammaproteobacteria (32.06%) and Alphaproteobacteria (26.63%) were found to predominate in Nephthea sp., while Spirochaetia (63.22%) and Gammaproteobacteria (13.01%) were most common in Sinularia sp. The coral pathogenic bacteria were identified 37 species. Among them, Vibrio campbellii was most abundant in seawater. Vibrio owensii was identified in every sample. In particular, unweighted pair group method with arithmetic mean (UPGMA) phylogenetic analysis showed diverse and species-specific differences in the microbiomes of Nephthea sp., Sinularia sp., and the surrounding seawater. This study represented the first c