Emma is a Marie Skłodowska-Curie postdoctoral fellow in the Environmental Genomics group at SciLifeLab. She is currently researching microbe-phage interactions in the Baltic Sea using meta-omic approaches.
Microbial meta-omics uncovers biogeochemical cycling in the terrestrial subsurface
The terrestrial subsurface remains an environment where there is limited understanding of the extant metabolisms, despite the reported large contribution of the deep subsurface to the overall biomass on this planet. In the deep crystalline bedrock of the Fennoscandian Shield at Olkiluoto, Finland, anoxic groundwater is geochemically gradated with depth and a terrestrial sulfate-methane transition zone is created by opposing gradients of abiotic methane and ancient seawater-derived sulfate. Sulfide is detected in relatively few groundwaters from this site, but it is important to understand the microbial drivers of sulfidogenesis as the bedrock will host a deep geological repository for the final safe disposal of spent nuclear fuel. To uncover the electron donors fueling sulfidogenesis, we investigated three groundwaters with varying chemistry and different concentrations of sulfide. Genome-resolved metaproteogenomics coupled with geochemical tools revealed a diversity of metabolic processes. In the deepest groundwater with the highest concentration of sulfide, geogenic hydrogen and primary production provide energy and carbon for sulfate-reducing bacteria. In the sulfate-methane transition zone, sulfur-disproportionating bacteria are active and possibly form a non-obligate syntrophy with anaerobic methanotrophic archaea (ANME). In the shallowest groundwater with limited sulfide production, a community of sulfate-reducing and sulfide-oxidizing bacteria mediate a cryptic sulfur cycle. This study highlights the importance of activity measurements for uncovering the roles of microorganisms in geochemical cycling and sheds light on sulfur cycling in the deep terrestrial subsurface.
Relevant published paper:
https://www.nature.com/articles/s41396-022-01207-w