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

Abstract

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.