Life on the edge: Microbial diversity, resistome, and virulome in soils from the union glacier cold desert

The high-latitude regions of Antarctica remain among the most remote, extreme, and least explored areas on Earth. Still, microbial life has been reported in these environments, with limited information on their genetic properties and functional capabilities. Although diverse autochthonous multidrug-resistant bacteria were found in Antarctic Peninsula soils, posing whether these soils could act as a source of resistance determinants that could emerge among pathogens, we still lack information regarding the resistome of areas closer to the South Pole. Moreover, no previous studies have evaluated the pathogenic potential of microbes inhabiting Antarctic soils. In this work, we combined metagenomic and culture-dependent approaches to investigate the microbial diversity, resistome, virulome, and mobile genetic elements (MGEs) in soils from Union Glacier, a cold desert in West Antarctica. Despite the extreme conditions, several bacterial phyla were found, predominating Actinomycetota and Pseudomonadota, with limited archaeal and fungal taxa. Contrastive with Ecology Glacier soils from King George Island, the Union Glacier soil bacterial community is significantly less diverse, mainly attributed to scarce moisture. We recovered >80 species-level representative genomes (SRGs) of predominant bacteria and an ammonia-oxidating nitrogen- and carbon-fixing archaeon from a novel species of Nitrosocosmicus. Several resistance and virulence genes were found in Union Glacier soils, similar to those in other Antarctic cold desert areas but significantly distinct from those observed in maritime Antarctica and other non-cryosphere biomes. Furthermore, we characterized bacterial isolates resistant to up to 24 clinical antibiotics, mainly Pseudomonas, Arthrobacter, Plantibacter, and Flavobacterium. Moreover, some isolates produced putative virulence factors, including siderophores, pyocyanins, and exoenzymes with hemolytic, lecithinase, protease, and DNAse activity. This evidence uncovers a largely unexplored resistome and virulome hosted by deep Antarctica's soil microbial communities and the presence of bacteria with pathogenic potential, highlighting the relevance of One Health approaches for environmental surveillance in this continent.