Skoltech researchers Svetlana Dubiley and Dmitry Sutormin have co-authored a recent paper “An Interplay between Viruses and Bacteria Associated with the White Sea Sponges Revealed by Metagenomics” that has been published in Life journal. The paper was previously released as a preprint at bioRxiv. The study is focused on investigation of microbial communities of the White Sea sponges via metagenomics. The scientists probed the microbiomes and viromes of cold-water sympatric sponges Isodictya palmata, Halichondria panicea, and Halichondria sitiens by 16S and shotgun metagenomics. They showed that the bacterial and viral communities associated with these White Sea sponges are species-specific and different from the surrounding water. Furthermore, bacteria that live inside sponges from the White Sea possess a variety of anti-phage defense systems. The abundance of defense systems was comparable in the metagenomes of the sponges and the surrounding water, thus distinguishing the White Sea sponges from those inhabiting the tropical seas. Using a network-based approach for the combined analysis of CRISPR-spacers and protospacers, the scientists showed that the virus–host interactions within the sponge-associated community are typically more abundant than the inter-community interactions. Additionally, we detected the occurrence of viral exchanges between the communities. Full text of the paper is available here.