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Chemolithotrophy in the continental deep subsurface: Sanford Underground Research Facility (SURF), USA.

Osburn MR, LaRowe DE, Momper LM, Amend JP - Front Microbiol (2014)

Bottom Line: However, the metabolic capabilities of these microorganisms and the degree to which they are dependent on surface processes are largely unknown.As a direct result of this compositional buffet, Gibbs energy calculations reveal an abundance of energy for microorganisms from the oxidation of sulfur, iron, nitrogen, methane, and manganese.Pyrotag DNA sequencing reveals diverse communities of chemolithoautotrophs, thermophiles, aerobic and anaerobic heterotrophs, and numerous uncultivated clades.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, University of Southern California Los Angeles, CA, USA ; Department of Earth and Planetary Sciences, Northwestern University Evanston, IL, USA.

ABSTRACT
The deep subsurface is an enormous repository of microbial life. However, the metabolic capabilities of these microorganisms and the degree to which they are dependent on surface processes are largely unknown. Due to the logistical difficulty of sampling and inherent heterogeneity, the microbial populations of the terrestrial subsurface are poorly characterized. In an effort to better understand the biogeochemistry of deep terrestrial habitats, we evaluate the energetic yield of chemolithotrophic metabolisms and microbial diversity in the Sanford Underground Research Facility (SURF) in the former Homestake Gold Mine, SD, USA. Geochemical data, energetic modeling, and DNA sequencing were combined with principle component analysis to describe this deep (down to 8100 ft below surface), terrestrial environment. SURF provides access into an iron-rich Paleoproterozoic metasedimentary deposit that contains deeply circulating groundwater. Geochemical analyses of subsurface fluids reveal enormous geochemical diversity ranging widely in salinity, oxidation state (ORP 330 to -328 mV), and concentrations of redox sensitive species (e.g., Fe(2+) from near 0 to 6.2 mg/L and Σ S(2-) from 7 to 2778μg/L). As a direct result of this compositional buffet, Gibbs energy calculations reveal an abundance of energy for microorganisms from the oxidation of sulfur, iron, nitrogen, methane, and manganese. Pyrotag DNA sequencing reveals diverse communities of chemolithoautotrophs, thermophiles, aerobic and anaerobic heterotrophs, and numerous uncultivated clades. Extrapolated across the mine footprint, these data suggest a complex spatial mosaic of subsurface primary productivity that is in good agreement with predicted energy yields. Notably, we report Gibbs energy normalized both per mole of reaction and per kg fluid (energy density) and find the later to be more consistent with observed physiologies and environmental conditions. Further application of this approach will significantly expand our understanding of the deep terrestrial biosphere.

No MeSH data available.


Related in: MedlinePlus

histograms of Gibbs energies shown in Figure 2. Histograms of the data from Figure 2 illustrating the relative influence of electron acceptors and donors on Gibbs energy when expressed in multiple ways. The left two panels (A,B) show Gibbs energies in units of kilojoules per mole of electron transferred, kJ (mol e−)−1, where the right panels (C,D) show Gibbs energies in units of Joules per kg of water, J (kg H2O)−1. The upper and lower panels show how various electron donors and acceptors, respectively, are distributed.
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Figure 5: histograms of Gibbs energies shown in Figure 2. Histograms of the data from Figure 2 illustrating the relative influence of electron acceptors and donors on Gibbs energy when expressed in multiple ways. The left two panels (A,B) show Gibbs energies in units of kilojoules per mole of electron transferred, kJ (mol e−)−1, where the right panels (C,D) show Gibbs energies in units of Joules per kg of water, J (kg H2O)−1. The upper and lower panels show how various electron donors and acceptors, respectively, are distributed.

Mentions: To explore this point further, Figure 5 condenses the data points from Figure 2 into histograms that more specifically illustrate the energy available from various electron acceptors (A, C) and electron donors (B, D). Panels A and B (Gibbs energy per mole e− transferred) show a bimodal distribution, with a larger peak centering on 0 kJ (mol e−)−1 and a smaller, broader peak extended from about −60 to −90 kJ (mol e−)−1. Note in Panel A (binned by electron acceptor) that reactions with O2, NO−3, and MnO2 are more exergonic and are clearly separated from the less exergonic reactions with Fe3O4, SO−24, S0, HCO−3, and CO. In Panel B (binned by electron donor), no trend is observed (Figure 5B). For example, Fe2+ oxidation (red bars) spans nearly the entire range from +30 to −100 kJ (mol e−)−1. Does this mean that aerobes and nitrate reducers should dominate the subsurface at SURF?


Chemolithotrophy in the continental deep subsurface: Sanford Underground Research Facility (SURF), USA.

Osburn MR, LaRowe DE, Momper LM, Amend JP - Front Microbiol (2014)

histograms of Gibbs energies shown in Figure 2. Histograms of the data from Figure 2 illustrating the relative influence of electron acceptors and donors on Gibbs energy when expressed in multiple ways. The left two panels (A,B) show Gibbs energies in units of kilojoules per mole of electron transferred, kJ (mol e−)−1, where the right panels (C,D) show Gibbs energies in units of Joules per kg of water, J (kg H2O)−1. The upper and lower panels show how various electron donors and acceptors, respectively, are distributed.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4228859&req=5

Figure 5: histograms of Gibbs energies shown in Figure 2. Histograms of the data from Figure 2 illustrating the relative influence of electron acceptors and donors on Gibbs energy when expressed in multiple ways. The left two panels (A,B) show Gibbs energies in units of kilojoules per mole of electron transferred, kJ (mol e−)−1, where the right panels (C,D) show Gibbs energies in units of Joules per kg of water, J (kg H2O)−1. The upper and lower panels show how various electron donors and acceptors, respectively, are distributed.
Mentions: To explore this point further, Figure 5 condenses the data points from Figure 2 into histograms that more specifically illustrate the energy available from various electron acceptors (A, C) and electron donors (B, D). Panels A and B (Gibbs energy per mole e− transferred) show a bimodal distribution, with a larger peak centering on 0 kJ (mol e−)−1 and a smaller, broader peak extended from about −60 to −90 kJ (mol e−)−1. Note in Panel A (binned by electron acceptor) that reactions with O2, NO−3, and MnO2 are more exergonic and are clearly separated from the less exergonic reactions with Fe3O4, SO−24, S0, HCO−3, and CO. In Panel B (binned by electron donor), no trend is observed (Figure 5B). For example, Fe2+ oxidation (red bars) spans nearly the entire range from +30 to −100 kJ (mol e−)−1. Does this mean that aerobes and nitrate reducers should dominate the subsurface at SURF?

Bottom Line: However, the metabolic capabilities of these microorganisms and the degree to which they are dependent on surface processes are largely unknown.As a direct result of this compositional buffet, Gibbs energy calculations reveal an abundance of energy for microorganisms from the oxidation of sulfur, iron, nitrogen, methane, and manganese.Pyrotag DNA sequencing reveals diverse communities of chemolithoautotrophs, thermophiles, aerobic and anaerobic heterotrophs, and numerous uncultivated clades.

View Article: PubMed Central - PubMed

Affiliation: Department of Earth Sciences, University of Southern California Los Angeles, CA, USA ; Department of Earth and Planetary Sciences, Northwestern University Evanston, IL, USA.

ABSTRACT
The deep subsurface is an enormous repository of microbial life. However, the metabolic capabilities of these microorganisms and the degree to which they are dependent on surface processes are largely unknown. Due to the logistical difficulty of sampling and inherent heterogeneity, the microbial populations of the terrestrial subsurface are poorly characterized. In an effort to better understand the biogeochemistry of deep terrestrial habitats, we evaluate the energetic yield of chemolithotrophic metabolisms and microbial diversity in the Sanford Underground Research Facility (SURF) in the former Homestake Gold Mine, SD, USA. Geochemical data, energetic modeling, and DNA sequencing were combined with principle component analysis to describe this deep (down to 8100 ft below surface), terrestrial environment. SURF provides access into an iron-rich Paleoproterozoic metasedimentary deposit that contains deeply circulating groundwater. Geochemical analyses of subsurface fluids reveal enormous geochemical diversity ranging widely in salinity, oxidation state (ORP 330 to -328 mV), and concentrations of redox sensitive species (e.g., Fe(2+) from near 0 to 6.2 mg/L and Σ S(2-) from 7 to 2778μg/L). As a direct result of this compositional buffet, Gibbs energy calculations reveal an abundance of energy for microorganisms from the oxidation of sulfur, iron, nitrogen, methane, and manganese. Pyrotag DNA sequencing reveals diverse communities of chemolithoautotrophs, thermophiles, aerobic and anaerobic heterotrophs, and numerous uncultivated clades. Extrapolated across the mine footprint, these data suggest a complex spatial mosaic of subsurface primary productivity that is in good agreement with predicted energy yields. Notably, we report Gibbs energy normalized both per mole of reaction and per kg fluid (energy density) and find the later to be more consistent with observed physiologies and environmental conditions. Further application of this approach will significantly expand our understanding of the deep terrestrial biosphere.

No MeSH data available.


Related in: MedlinePlus