Potential metabolic strategies of widely distributed holobionts in the oceanic archipelago of St Peter and St Paul (Brazil)

Sponges are one of the most complex symbiotic communities and while the taxonomic composition of associated microbes has been determined, the biggest challenge now is to uncover their functional role in symbiosis. We investigated the microbiota of two widely distributed sponge species, regarding both their taxonomic composition and their functional roles. Samples of Didiscus oxeata and Scopalina ruetzleri were collected in the oceanic archipelago of St Peter and St Paul and analysed through metagenomics. Sequences generated by 454 pyrosequencing and Ion Torrent were taxonomically and functionally annotated on the MG-RAST server using the GenBank and SEED databases, respectively. Both communities exhibit equivalence in core functions, interestingly played by the most abundant taxa in each community. Conversely, the microbial communities differ in composition, taxonomic diversity and potential metabolic strategies. Functional annotation indirectly suggests differences in preferential pathways of carbon, nitrogen and sulphur metabolisms, which may indicate different metabolic strategies.