Genomic Evidence for Formate Metabolism by Chloroflexi as the Key to Unlocking Deep Carbon in Lost City Microbial Ecosystems

McGonigle, Julia M.; Lang, Susan Q.; Brazelton, William J. 2020. Applied and Environmental Microbiology
PDF
McGonigle et al. - 2020 - Genomic Evidence for Formate Metabolism by Chlo.pdf
Supplement
zenodo.3522423
DOI
10.1128/AEM.02583-19

Link to online paper: https://journals.asm.org/doi/10.1128/AEM.02583-19

Abstract

The Lost City hydrothermal field on the Mid-Atlantic Ridge supports dense microbial life on the lofty calcium carbonate chimney structures. The vent field is fueled by chemical reactions between the ultramafic rock under the chimneys and ambient seawater. These serpentinization reactions provide reducing power (as hydrogen gas) and organic compounds that can serve as microbial food; the most abundant of these are methane and formate. Previous studies have characterized the interior of the chimneys as a single-species biofilm inhabited by the Lost City Methanosarcinales, but they also indicated that this methanogen is unable to metabolize formate. The new metagenomic results presented here indicate that carbon cycling in these Lost City chimney biofilms could depend on the metabolism of formate by Chloroflexi populations. Additionally, we present evidence for metabolically diverse, formate-utilizing Sulfurovum populations and new genomic and phylogenetic insights into the unique Lost City Methanosarcinales.