Analysis of bacterial diversity in sponges collected off Chujado, an Island in Korea, using barcoded 454 pyrosequencing: analysis of a distinctive sponge group containing Chloroflexi.

The bacterial diversity of 14 sponges belonging to 5 different orders that were collected around Chuja Island, Korea was investigated using barcoded 454 pyrosequencing. The sponges contained many unidentified bacterial groups (e.g. more than half of the taxa at the family level) that were known only in environmental sequences and obtained from culture-independent methods. Five of the sponges were clustered into one notable group (CF group), which was distinguished from the other sponges in accordance with bacterial composition (the other sponges may be separated into more groups but clustering is not clear). The CF group contained high amounts of Chloroflexi (25.0-47.7%) and moderate amounts of Gemmatimonadetes (2.3-7.0%), AncK6 (0.6-2.2%), PAUC34f (0.8-6.0%), Acidobacteria (3.7-9.6%), and SBR1093 (1.8-5.6%) exclusively or almost exclusively to this group. Sponges in the CF group also showed higher diversity (e.g. Shannon index) than the other sponges and contained group-specific taxonomic lineages (e.g. class or family level) from group-specific phyla and even from the Proteobacteria and Actinobacteria, which were detected in all sponges at the phylum level. The CF group may be one of the most distinctive groups in sponges in terms of bacterial diversity.