Antarctic soil microbiomes encode structurally conserved and phylogenetically diverse beta‐lactamases

Antimicrobial resistance is a major global health threat shaped not only by clinical settings but also by environmental reservoirs, in line with the One Health framework. Antarctic and Subantarctic soils represent a largely unexplored component of the environmental resistome, particularly beta‐lactamases, whose diversity, structural features, and biogeographic patterns remain poorly resolved. Here, we applied an integrative metagenomic approach combining sequence‐, structure‐, and function‐based similarity to systematically identify putative beta‐lactamase orthologs across an extensive collection of Antarctic and Subantarctic soil metagenomes. We detected multiple beta‐lactamase classes and families, with a predominance of class A serine beta‐lactamases and subclass B3 metallo‐beta‐lactamases. Several previously uncharacterized families and divergent variants were identified, many of which retain conserved catalytic architectures. Beta‐lactamase diversity and relative abundance were strongly patterned across three major biogeographic clusters: Subantarctic islands, the Antarctic Peninsula and surrounding islands, and continental cold deserts, mirroring shifts in microbial community composition. The Antarctic Peninsula and maritime Antarctica exhibited the highest overall beta‐lactamase abundance. Analysis of more than 3500 metagenome‐assembled genomes indicated that most beta‐lactamases were encoded by members of p_Pseudomonadota and p_Bacteroidota , with additional representatives distributed across other bacterial phyla. A subset was linked to mobile genetic elements, suggesting a latent but limited potential for horizontal gene transfer. Together, these findings reveal a geographically organized and compositionally diverse repertoire of beta‐lactamases in (sub)Antarctic soils, underscoring the evolutionary persistence of conserved catalytic frameworks in cold environments and highlighting the contribution of remote ecosystems to global resistome diversity.