Comparative Genomics Reveals Metabolic Specificity of Isolated from a Marine Sponge and the Genomic Repertoire for Host-Bacteria Symbioses.

The most recently described bacterial members of the genus have been found in association with a wide variety of marine invertebrates. Despite their ubiquity in the host holobiont, limited information is available on the molecular genomic signatures of the symbiotic association of with marine sponges. Here, we generated a draft genome of sp. OPT23 isolated from the intertidal marine sponge and performed comprehensive comparative genomics analyses. Genome-specific analysis and metabolic pathway comparison of the members of the genus revealed the presence of gene clusters encoding for unique metabolic features, such as the utilization of carbon sources through lactate, L-rhamnose metabolism, and a phenylacetic acid degradation pathway in sp. OPT23. Moreover, the genome harbors genes encoding for eukaryotic-like proteins, such as ankyrin repeats, tetratricopeptide repeats, and Sel1 repeats, which likely facilitate sponge-bacterium attachment. The genome also encodes major secretion systems and homologs of effector molecules that seem to enable the sponge-associated bacterium to interact with the sponge and deliver the virulence factors for successful colonization. In conclusion, the genome analysis of sp. OPT23 revealed the presence of adaptive genomic signatures that might favor their symbiotic lifestyle within the sponge host.