Interação vírus-bactéria na Ilha Rei George, Antártica: papel dos bacteriófagos na adaptação de Rummeliibacillus stabekisii PP9 e na ecologia viral de solos contaminados por hidrocarbonetos

Abstract

Interactions between bacteria and bacteriophages can promote bacterial adaptation and survival in extreme environments. However, the viral diversity of Antarctic soils and their interactions with bacterial communities remain poorly explored. In this context, the first objective of this study was to evaluate, at the genomic level, the role of bacteria–bacteriophage interactions in the adaptation of Rummeliibacillus stabekisii to adverse environmental conditions. Using the PHASTER program for prophage analysis, it was observed that strain PP9, isolated from Antarctic soil, harbors three intact and two defective prophages in its genome, differing from other strains of the species, isolated from spacecraft assembly cleanrooms subjected to rigorous cleaning, which presented only defective phages. Recombination hotspots were observed in specific regions of the PP9 genome, where prophages 3 and 5 are located, indicating that these regions function as centers for the incorporation of new genes via horizontal gene transfer. Investigation of the genetic context of the intact prophages revealed genes potentially associated with the adaptation of strain PP9 to the environment, such as gerABC (involved in spore germination) and ynfA (related to efflux proteins). Furthermore, the induction of at least two of the three intact prophages present in the PP9 genome was confirmed by flow cytometry. The second objective of this study was to characterize, through metagenomic approaches, the viral diversity in three hydrocarbon-contaminated Antarctic soils and two soils characterized as uncontaminated. Analysis of viral contigs, assembled with Megahit and identified using VirSorter from five samples, indicated the predominance of the class Caudoviricetes in Antarctic soils. Our results showed that the presence of Caudoviricetes viruses in the soils is directly related to phosphorus scarcity, representing 90% of the viruses detected in contaminated soils and 60% in uncontaminated soils. Host identification revealed that most viruses detected in Antarctic soils belong to bacterial genera (from the phyla Pseudomonadota and Actinomycetota) previously described as hydrocarbon degraders. Viruses of the genus Stormageddonvirus (bacteriophages infecting Gordonia bacteria) were the most abundant in Antarctic soils. Additionally, our results identified auxiliary viral metabolic genes linked to nitrogen cycles, such as amoC (ammonia monooxygenase), and phosphorus cycles, such as pho (phosphate regulon). These findings reinforce the role of viruses as agents of genetic and ecological modulation in Antarctic ecosystems, highlighting the continent as a potential viral reservoir.