BioProject

Marine sponges host abundant and diverse associated bacteria, some of which known to produce biologically active natural products. More...

Marine sponges host abundant and diverse associated bacteria, some of which known to produce biologically active natural products. Although much research effort has been applied to cultivate sponge-associated microorganisms, we still lack the ability to capture the full phylogenetic breadth of this symbiotic consortium in the laboratory. This study uses a cultivation-independent, shotgun metagenomics approach to unveil the taxonomic and functional features of the model sponge host Spongia sp. and its environmental surroundings (seawater and sediments). Samples were taken off the coast of Algarve, South Portugal (North-east Atlantic), and subjected to Illumina sequencing after microbial metagenomic DNA extraction. Taxonomic and functional profiles were assessed using MG-RAST with the Genbank and COG databases, respectively. Most abundant phyla in the sponge microbiome were Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Chloroflexi, Cyanobacteria, Planctomycetes and Acidobacteria, in this order, altogether comprising 84.35% of all the classifiable sequence reads. In contrast, the dominant phyla in seawater were Bacteroidetes and Proteobacteria (89.3% of all classifiable reads), whereas sediments were dominated by Proteobacteria, Bacteroidetes, Planctomycetes, Actinobacteria and Firmicutes (85%). We found significantly higher frequencies of transcription and translation termination factors in sediments and seawater, respectively, than in marine sponge microbial metagenomes. Moreover, higher abundances of motility and chemotaxis gene reads were found in the former microhabitats in comparison with the marine sponge microbiome, where a conspicuously higher frequency of Clustered Regularly Interspaced Palindromic Repeats (CRISPRs), accompanied by much lower viral abundance, was otherwise observed. These results suggest a highly distinct microbiome inhabiting Spongia sp., both in terms of taxonomy and function, characterized by the prevalence of k-strategy prokaryotes which collectively possess a sophisticated, early-branched viral defence system. Less...