Deep-sea siliceous sponges harbor distinct and functionally diverse microbiomes.

Deep-sea siliceous sponges host microbial communities dominated by ammonia-oxidizing archaea, with one sponge hosting only Nitrosopumilaceae.

• Why it matters: Understanding the microbiomes of deep-sea siliceous sponges is crucial because they play key roles in ocean biogeochemistry and nutrient cycling, yet remain poorly characterized.
• What they did: Shotgun metagenomics was used to analyze 13 siliceous sponges from depths of 400 to 1,900 meters near Puerto Rico, assembling 176 genomes from 20 bacterial and 1 archaeal phylum.
• The result: Microbial communities showed limited diversity, with evidence of metabolic capabilities for carbon, nitrogen, and sulfur cycling, indicating metabolic flexibility that may support sponge health in oligotrophic environments.