Project description:Marine sponges are essential for coral reefs to thrive and harbour a diverse microbiome that is thought to contribute to host health. Although the overall function of sponge symbionts has been increasingly described, in-depth characterisation of each taxa remains challenging, with many sponge species hosting up to 3,000 distinct microbial species. Recently, the sponge Ianthella basta has emerged as a model organism for symbiosis research, hosting only three dominant symbionts: a Thaumarchaeotum, a Gammaproteobacterium, and an Alphaproteobacterium and a range of other minor taxa. Here, we retrieved metagenome assembled genomes (MAGs) for >90% of I. basta’s microbial community which allowed us to make a complete metabolic reconstruction of the sponge’s microbiome, identifying metabolic complementarity between microbes, as well as the importance of symbionts present in low abundance. We also mined the metagenomes for putative viral sequences, highlighting the contribution of viruses to the overall metabolism of the sponge, and complement this data with metaproteomic sequencing to identify active metabolic pathways in both prokaryotes and viruses. This data now allows us to use I. basta as a model organism for studying host-microbe interactions and provides a basis for future (genomic) manipulative experiments.
Project description:<p>Marine sponges can host abundant and diverse microbiomes, which can largely influence the metabolism and other phenotypic traits of the host. However, information on the potential relationships between sponge microbiomes and metabolic signatures, other than secondary metabolites explored for biotechnological purposes, needs further investigation. Applying an integrated approach, we investigated the microbiomes associated with 4 ubiquitous Mediterranean sponge species (i.e., Petrosia ficiformis, Chondrosia reniformis, Crambe crambe and Chondrilla nucula), correlated with their metabolomic patterns (in terms of lipidomics) and microbial predicted functions. Microscopy observations of sponge tissues revealed differences in microbial abundances, which, however, were only partially linked to their diversity assessed through metabarcoding. The microbiomes of the 4 sponges showed a species-specific composition and a different core size, which was independent from the microbial diversity of the surrounding seawater. Predicted functions of the associated microbiomes allowed identifying 2 functional host clusters: one more related to heterotrophic pathways and the other more linked to phototrophic activities. Differences in the microbiomes were also associated with different metabolic profiles, mostly due to specific compounds characterizing the host and its microbiome. Overall, this study provides new insights on the functionality of sponges and their prokaryotic symbioses’, and in particular, it discloses a descriptive sketch of the diverse compartments forming the sponge holobiont.</p>