Evidence for Trace Gas Metabolism and Widespread Antibiotic Synthesis in an Abiotically Driven, Antarctic Soil Ecosystem.

The McMurdo Dry Valleys (MDVs) of Antarctica are a uniquely pristine, low-biodiversity model system for understanding fundamental ecological phenomena, the impact of a warming climate on ecosystem functioning, community structure and composition and the dynamics of adaptation. Despite the scientific value of this system, we still know little about the functional ecology of its biota, especially the bacteria. Here, we analysed the bacterial taxonomic and functional diversity of 18 shotgun metagenomes using the VEBA metagenome processing pipeline. We recovered 701 medium-to-high quality metagenome-assembled genomes (MAGs) (≥ 50% completeness and contamination < 10%) and 201 high-quality MAGs (≥ 80% completeness and < 10% contamination), almost 50% more than found in similar sites previously. We found that: (1) community composition shifts along environmental gradients correlated with soil moisture, elevation and distance to the coast; (2) many MDV bacteria are capable of performing trace gas metabolism; (3) genes associated with antibiotic-mediated competitive interactions (e.g., antibiotic biosynthesis and antibiotic resistance genes) are widespread; and (4) MDV bacteria employ survival strategies common to bacteria in similarly extreme environments. This study provides novel insight into microbial survival strategies in extreme environments and lays the groundwork for a more comprehensive understanding of the autecology of MDV bacteria.