IV Jornadas Latinoamericanas de Bacteriófagos

Antarctic marine ecosystems harbor diverse and largely uncharacterized viral communities, representing a significant reservoir of novel antimicrobial enzymes. We performed a comparative metaviromic analysis of viral assemblages from two Antarctic coastal sites with contrasting levels of anthropogenic influence: the more impacted Base Prat and the remote, pristine Base Yelcho. Using an integrated pipeline, we identified approximately 4,000 representative viral operational taxonomic units (vOTUs) for downstream analysis.
Taxonomic profiling revealed a similar viral class composition at both sites, dominated by Caudoviricetes. At the order level, however, most sequences were unclassified, indicating substantial novelty and the presence of putative new lineages within the Caudoviricetes. Family-level patterns revealed site-specific differences, including a relative increase in Kyanoviridae and a reduced representation of Peduoviridae at Yelcho compared to Prat. Predicted host distributions also diverged: Prat's community was dominated by viruses associated with Pseudomonas and Pseudoalteromonas, whereas Yelcho exhibited a more even host distribution spanning genera such as Algibacter and Aureispira.
Normalized Pfam domain profiles uncovered distinct functional signatures. The Yelcho virome was enriched in domains associated with recombination and DNA processing (e.g., AAA+ ATPases, HNH endonucleases), suggesting heightened genomic plasticity. Notably, Yelcho also showed a significantly higher relative abundance of lysis-associated domains, including Peptidase_M23, Peptidase_M10, CHAP, and LysM, consistent with greater endolysin diversity and lytic potential. In contrast, the Prat virome was enriched in structural viral domains, such as portal and capsid proteins, pointing to a more stable viral assemblage. Lysis-related domains in Prat were predominantly amidases and cell-wall modification enzymes rather than canonical endopeptidases. Several Antarctic endolysins exhibited sequence and structural similarity to enzymes active against pathogens of interest, including Pseudomonas, Klebsiella, and Acinetobacter.
Our findings demonstrate that Antarctic coastal viromes are structurally and functionally shaped by local ecological conditions and constitute a promising source of novel endolysins with potential biotechnological and antimicrobial applications.