Prokaryotic communities of the sponge Dactylospongia elegans

Sponges were widespread in the South China Sea. Reports have shown numerous natural products extracted from sponges . Sponge-associated microbes have also been reported in several works. However, systematic studies on sponge-associated prokaryotic communities in the South China Sea, especially those associated with cyanobacterial symbionts such as “Ca. Synechococcus spongiarum”, remain limited at present. Here, sponge specimens of Dactylospongia elegans were collected from the South China Sea. Sponge associated prokaryotic communities were investigated using barcoded 16S rRNA gene amplicons through next generation sequencing methods, which showed high abundance of the cyanobacterial symbiont “Ca. Synechococcus spongiarum”. More reliable metagenomic method were also used to resolve the prokaryotic community and highly abundant poribacterial symbionts were revealed. Several nearly-complete genomes of sponge symbionts were further retrieved from metagenomes, providing an opportunity to reveal the complex symbiotic networks in the sponge D. elegans.