Methane release drives subglacial microbial community assembly at the western margin of the Greenland Ice Sheet

Abstract

The basal environments of ice sheets play an important role as places of methane (CH4) production, storage, and release. Recent investigations have confirmed the release of subglacial methane of microbial origin at the western margin of the Greenland Ice Sheet (GrIS). This methane may then serve as a substrate for methane-consuming microorganisms and thus significantly shape microbial community assembly in GrIS subglacial environments. We conducted a comparative analysis of the composition of exported microbial assemblages from six regions spanning a 2,000-km transect along the western margin of the GrIS. Based on 16S rRNA gene sequences, we identified taxa predominantly affiliated with Pseudomonadota (formerly Proteobacteria), Actinomycetota (formerly Actinobacteriota), and Acidobacteriota. Within the Pseudomonadota, notable genera such as Rhodoferax, Polaromonas, and the methylotrophic Crenothrix and Methylotenera were identified as the most abundant. Importantly, we observed a pattern in community composition related to measured methane concentrations at each site, resulting in three distinct clusters: samples from sites with atmospheric methane levels (i.e., with no significant methane release), those from sites with elevated methane concentrations, and methane release hotspots. Our results align with recent findings, suggesting that microbial communities colonizing methane-emitting sites may have the potential to utilize methane as a resource, thereby reducing its release into the atmosphere and so mitigating its impact on climate change. Furthermore, our findings may facilitate the identification of potential methane release hotspots based on microbial community analysis.