Total and active communities of Tedania ignis. The total and active microbial community dynamics of the sponge Tedania ignis in a sustained mariculture setup over time

Sponges contain multitudes of symbiotic microbes with exceptional diversity, particularly seen with large sequencing projects, such as the sponge microbiome project. Attempts to obtain enough biomass for experiments remains a key issue which is holding back the area of research. To this end, several groups have tried to develop a mariculture approach to grow sponges in the laboratory and thus protect wild stocks. What is not clear, however, are whether microbial communities in maricultured sponges are stable upon entering the ex-situ mariculture setup and whether we are capturing the active community within the sponge. To explore these changes, wild specimens of Tedania ignis were collected and cultivated in a recirculating mariculture setup. After extracting total DNA and RNA, and the generation of cDNA, the V4 hypervariable region of the 16S rRNA gene was sequenced to observe changes in the microbial structure of the sponge. The results showed high abundances of Endozoicomonas and Candidatus Branchiomonas across all samples. Populations of Mycobacteria and Sulfurovum were unique to the gDNA samples, with time point changes consisting mainly of unclassified bacteria. Within the cDNA samples, increases in the abundance of unclassified and rarer bacteria such as Actibacter and the family Desulfobacteraceae, were observed. Increases in alpha and beta diversity were seen for both the gDNA and cDNA samples as time increased. This research contributes to understanding how the sponge microbiome fluctuates in mariculture, and also to showing differences in diversity by incorporating cDNA into microbiome analyses.