Viral Diversity in Polar Hydrocarbon-Contaminated Soils: A Transect Study from King George Island, Antarctica

Viruses are key components of soils, influencing microbial dynamics and biogeochemical cycles. Here, we used shotgun metagenomics to analyze the virome of hydrocarbon-contaminated and uncontaminated soils from King George Island, Antarctica. Viral sequences were obtained from metagenomes of all soils; however, the relative abundance of viruses was higher in hydrocarbon-contaminated soils compared to uncontaminated soils. Our results indicate that viral distribution correlates with polycyclic aromatic hydrocarbons (PAHs) in King George Island soil (p = 0.05). Taxonomic analysis of viral contigs revealed viruses from realms Duplodnaviria, Varidnaviria, Monodnaviria, and Riboviria. While Caudoviricetes (realm Duplodnaviria) represented more than 90% of the relative abundance of viruses found in hydrocarbon-contaminated soils, this class represented less than 62% of the viruses of uncontaminated soils. Most viral hosts detected in King George Island soils belonged to hydrocarbon-degrading bacterial genera from the phyla Pseudomonadota and Actinomycetota. Hydrocarbon contamination resulted in the enrichment of well-characterized viruses at the expense of previously uncharacterized viral taxa, which were predominantly detected in non-contaminated soils. Among them, Gordonia-related Stormageddonvirus was the most abundant viral entity identified in King George Island soil. Viral auxiliary metabolic genes (AMGs) associated with nitrogen and phosphate cycles were found in different Caudoviricetes-related contigs. Our results further indicate that Caudoviricetes abundance is correlated with the carbon: phosphate (C:P) ratio in King George Island soils. We propose the Caudoviricetes may actively contribute to microbial competition for phosphorus in hydrocarbon-contaminated soils. These findings shed light on the intricate interplay between viruses, microbial hosts, and environmental contamination in Antarctic soils.