TY - JOUR
T1 - Variations in microbial carbon sources and cycling in the deep continental subsurface
AU - Simkus, Danielle N.
AU - Slater, Greg F.
AU - Lollar, Barbara Sherwood
AU - Wilkie, Kenna
AU - Kieft, Thomas L.
AU - Magnabosco, Cara
AU - Lau, Maggie C.Y.
AU - Pullin, Michael J.
AU - Hendrickson, Sarah B.
AU - Wommack, K. Eric
AU - Sakowski, Eric G.
AU - Heerden, Esta van
AU - Kuloyo, Olukayode
AU - Linage, Borja
AU - Borgonie, Gaetan
AU - Onstott, Tullis C.
N1 - Funding Information:
This work was supported by National Science Foundation (NSF) funding to T.C.O. (EAR-0948659) and T.L.K. (EAR-0948335 and EAR-1141435) and funding from the Natural Science and Engineering Research Council ( NSERC ) of Canada to G.F.S. via Discovery (RGPIN-288309-2009) and CREATE grants (Canadian Astrobiology Training Program CREAT 371308-09). Metagenome sequencing and analyses of BE2011, BE2012, DR5IPC, T109 Bh2 and TT107 were supported by NASA EPSCoR/New Mexico Space Grant Consortium funding to T.L.K. Metagenome data from sample TT107 were made possible by the Deep Carbon Observatory’s Census of Deep Life supported by the Alfred P. Sloan Foundation and partial salary support for several co-authors was from the Deep Carbon Observatory Deep Energy Directorate. Sequencing was performed at the Marine Biological Laboratory (MBL, Woods Hole, MA, USA) and we are grateful for the assistance of Mitch Sogin, Susan Huse, Joseph Vineis, Andrew Voorhis, Sharon Grim, and Hilary Morrison of MBL. C. Magnabosco was supported by the NSF Graduate Research Fellowship to C. Magnabosco (Grant No. DGE-1148900) and the Center for Dark Energy Biosphere Investigations (C-DEBI) Graduate Research Fellowship. (Disclaimer: Any opinion, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation. This is C-DEBI contribution 278). We are grateful for the support of Sibanye Gold Ltd. and AngloGold Ashanti Ltd., South Africa and the management and staff of Beatrix, Driefontein, Kloof and Tau Tona mines. We give credits to S. Maphanga of Beatrix Au mine, H. van Niekerk of Driefontein Au mine, and F. Vermeulen, M. Pienaar and A. Munro of Tau Tona Au mine. We thank E. Cason, B. Pfeiffer, C. Simon, Melody Lindsay, L. Snyder, J.-G. Vermeulen, A.M. Meyer, M. Maleke, T. Tlalajoe, V. Mescheryakov, for their assistance in the collection, preservation and field analyses the fracture water samples. We also thank George Rose (Princeton University) who designed and constructed the sampling manifold. Finally we thank Kathryn Elder and Sue Handwork of the NOSAMS facility for processing our 14 C samples.
Publisher Copyright:
© 2015 Elsevier Ltd.
PY - 2016/1/15
Y1 - 2016/1/15
N2 - Deep continental subsurface fracture water systems, ranging from 1.1 to 3.3km below land surface (kmbls), were investigated to characterize the indigenous microorganisms and elucidate microbial carbon sources and their cycling. Analysis of phospholipid fatty acid (PLFA) abundances and direct cell counts detected varying biomass that was not correlated with depth. Compound-specific carbon isotope analyses (δ13C and δ14C) of the phospholipid fatty acids (PLFAs) and carbon substrates combined with genomic analyses did identify, however, distinct carbon sources and cycles between the two depth ranges studied. In the shallower boreholes at circa 1kmbls, isotopic evidence indicated microbial incorporation of biogenic CH4 by the in situ microbial community. At the shallowest site, 1.05kmbls in Driefontein mine, this process clearly dominated the isotopic signal. At slightly deeper depths, 1.34kmbls in Beatrix mine, the isotopic data indicated the incorporation of both biogenic CH4 and dissolved inorganic carbon (DIC) derived from CH4 oxidation. In both of these cases, molecular genetic analysis indicated that methanogenic and methanotrophic organisms together comprised a small component (<5%) of the microbial community. Thus, it appears that a relatively minor component of the prokaryotic community is supporting a much larger overall bacterial community in these samples. In the samples collected from >3kmbls in Tau Tona mine (TT107, TT109 Bh2), the CH4 had an isotopic signature suggesting a predominantly abiogenic origin with minor inputs from microbial methanogenesis. In these samples, the isotopic enrichments (δ13C and δ14C) of the PLFAs relative to CH4 were consistent with little incorporation of CH4 into the biomass. The most 13C-enriched PLFAs were observed in TT107 where the dominant CO2-fixation pathway was the acetyl-CoA pathway by non-acetogenic bacteria. The differences in the δ13C of the PLFAs and the DIC and DOC for TT109 Bh2 were ~-24‰ and 0‰, respectively. The dominant CO2-fixation pathways were 3-HP/4-HB cycle>acetyl-CoA pathway>reductive pentose phosphate cycle.
AB - Deep continental subsurface fracture water systems, ranging from 1.1 to 3.3km below land surface (kmbls), were investigated to characterize the indigenous microorganisms and elucidate microbial carbon sources and their cycling. Analysis of phospholipid fatty acid (PLFA) abundances and direct cell counts detected varying biomass that was not correlated with depth. Compound-specific carbon isotope analyses (δ13C and δ14C) of the phospholipid fatty acids (PLFAs) and carbon substrates combined with genomic analyses did identify, however, distinct carbon sources and cycles between the two depth ranges studied. In the shallower boreholes at circa 1kmbls, isotopic evidence indicated microbial incorporation of biogenic CH4 by the in situ microbial community. At the shallowest site, 1.05kmbls in Driefontein mine, this process clearly dominated the isotopic signal. At slightly deeper depths, 1.34kmbls in Beatrix mine, the isotopic data indicated the incorporation of both biogenic CH4 and dissolved inorganic carbon (DIC) derived from CH4 oxidation. In both of these cases, molecular genetic analysis indicated that methanogenic and methanotrophic organisms together comprised a small component (<5%) of the microbial community. Thus, it appears that a relatively minor component of the prokaryotic community is supporting a much larger overall bacterial community in these samples. In the samples collected from >3kmbls in Tau Tona mine (TT107, TT109 Bh2), the CH4 had an isotopic signature suggesting a predominantly abiogenic origin with minor inputs from microbial methanogenesis. In these samples, the isotopic enrichments (δ13C and δ14C) of the PLFAs relative to CH4 were consistent with little incorporation of CH4 into the biomass. The most 13C-enriched PLFAs were observed in TT107 where the dominant CO2-fixation pathway was the acetyl-CoA pathway by non-acetogenic bacteria. The differences in the δ13C of the PLFAs and the DIC and DOC for TT109 Bh2 were ~-24‰ and 0‰, respectively. The dominant CO2-fixation pathways were 3-HP/4-HB cycle>acetyl-CoA pathway>reductive pentose phosphate cycle.
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U2 - 10.1016/j.gca.2015.10.003
DO - 10.1016/j.gca.2015.10.003
M3 - Article
AN - SCOPUS:84947475520
SN - 0016-7037
VL - 173
SP - 264
EP - 283
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -