Subsurface carbon monoxide oxidation capacity revealed through genome-resolved metagenomics of a carboxydotroph

Abstract

Microbial communities play important roles in the biogeochemical cycling of carbon in the Earths deep subsurface. Previously, we demonstrated changes to the microbial community structure of a deep aquifer (1.4 km) receiving 150 tons of injected supercritical CO2 (scCO2) in a geosequestration experiment. The observed changes support a key role in the aquifer microbiome for the thermophilic CO-utilising anaerobe Carboxydocella, which decreased in relative abundance post-scCO2 injection. Here, we present results from more detailed metagenomic profiling of this experiment, with genome resolution of the native carboxydotrophic Carboxydocella. We demonstrate a switch in CO-oxidation potential by Carboxydocella through analysis of its carbon monoxide dehydrogenase (CODH) gene before and after the geosequestration experiment. We discuss the potential impacts of scCO2 on subsurface flow of carbon and electrons from oxidation of the metabolic intermediate carbon monoxide (CO). Originality-Significance StatementThe research conducted in this study is associated with one of the worlds largest demonstrations of carbon geosequestration - The Cooperative Research Centre for Greenhouse Gas Technologies Otway Project (Victoria, Australia). Our results expand the ecology of CO-utilising microbes to include the terrestrial deep subsurface through genome-resolved metagenomics of an aquifer-native carboxydotroph.