A metagenomic window into carbon metabolism at 3 km depth in Precambrian continental crust

Cara Magnabosco, Kathleen Ryan, Maggie C.Y. Lau, Olukayode Kuloyo, Barbara Sherwood Lollar, Thomas L. Kieft, Esta Van HeerDen, Tullis C. Onstott

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52 Scopus citations

Abstract

Subsurface microbial communities comprise a significant fraction of the global prokaryotic biomass; however, the carbon metabolisms that support the deep biosphere have been relatively unexplored. In order to determine the predominant carbon metabolisms within a 3-km deep fracture fluid system accessed via the Tau Tona gold mine (Witwatersrand Basin, South Africa), metagenomic and thermodynamic analyses were combined. Within our system of study, the energy-conserving reductive acetyl-CoA (Wood-Ljungdahl) pathway was found to be the most abundant carbon fixation pathway identified in the metagenome. Carbon monoxide dehydrogenase genes that have the potential to participate in (1) both autotrophic and heterotrophic metabolisms through the reversible oxidization of CO and subsequent transfer of electrons for sulfate reduction, (2) direct utilization of H 2 and (3) methanogenesis were identified. The most abundant members of the metagenome belonged to Euryarchaeota (22%) and Firmicutes (57%) - by far, the highest relative abundance of Euryarchaeota yet reported from deep fracture fluids in South Africa and one of only five Firmicutes-dominated deep fracture fluids identified in the region. Importantly, by combining the metagenomics data and thermodynamic modeling of this study with previously published isotopic and community composition data from the South African subsurface, we are able to demonstrate that Firmicutes-dominated communities are associated with a particular hydrogeologic environment, specifically the older, more saline and more reducing waters.

Original languageEnglish (US)
Pages (from-to)730-741
Number of pages12
JournalISME Journal
Volume10
Issue number3
DOIs
StatePublished - Mar 1 2016

All Science Journal Classification (ASJC) codes

  • Microbiology
  • Ecology, Evolution, Behavior and Systematics

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    Magnabosco, C., Ryan, K., Lau, M. C. Y., Kuloyo, O., Sherwood Lollar, B., Kieft, T. L., Van HeerDen, E., & Onstott, T. C. (2016). A metagenomic window into carbon metabolism at 3 km depth in Precambrian continental crust. ISME Journal, 10(3), 730-741. https://doi.org/10.1038/ismej.2015.150