Ecological and metabolic signatures of biofilm viromes across a national river surveillance network

River biofilm viromes across England’s River Surveillance Network show extensive viral novelty, with 93% of 38,534 vOTUs unassigned to known families and no vOTU in >8.3% of samples.

• Why it matters: Endogenous viral communities in benthic biofilms are poorly resolved at national scales, limiting how well river health and microbial ecology can be interpreted from viral diversity and function.
• What they did: The study analyzed 447 biofilm metagenomes from 146 RSN sites sampled in spring and autumn from 2021–2023, integrating vOTUs, water-quality gradients, predicted host associations, and auxiliary metabolic genes.
• The result: Virome composition was structured by season (family-level PERMANOVA R2 = 0.050, p = 0.001; year p = 0.08), linked weakly to water chemistry (envfit R2 ≤ 0.066), and enriched for nucleotide metabolism and DNA methylation AMGs, including nrdA/nrdB.