Antarctic Environmental Resistomes Closely Associated with Human and Animal Waste Releases

Antarctica harbors a diverse spectrum of antibiotic resistance genes (ARGs) across lake, soil, and seawater environments. However, linkages between resistomes in waste-impacted and pristine settings are not well understood in polar settings, especially how phage, plasmids, and microbial community assembly influence the spatial distribution of ARGs. Metagenomic sequencing of 85 Antarctic samples showed 10-fold greater ARG abundances near animal and human waste-impacted sites compared with more remote settings, including glacial, lake, soil, and offshore seawater sites (-1.9 to -0.1 log10(ARGs/cell), P < 0.01), although (except for glaciers) resistome compositions were broadly similar. Based on metagenomic data, plasmids appear to be more associated with ARGs than phages in the Antarctic samples, with Pseudomonas, Staphylococcus, Bacillus, and Mycobacterium being primarily associated with ARG prevalence because they dominate local microbial assemblages. These primary taxa exhibit wide cross-setting prevalence and are not significantly impacted by local environmental selection (P > 0.05, SNPs-RDA). As such, human- and animal-waste-impacted locations, which have higher microbial migration rates (m = 10.8, NCM), are primary sources of ARG-containing and assembly predominant bacteria in Antarctic settings. Thus, better management of waste releases from human settlements must be central to retaining "pristine" Antarctic environments against the globally expanding resistomes.