In Situ Cultivation of Subsurface Microorganisms in a Deep Mafic Sill: Implications for SLiMEs |
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| Authors: | B J Silver T C Onstott G Rose L-H Lin C Ralston B Sherwood-Lollar |
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| Institution: | 1. Department of Geosciences , Princeton University , Princeton, NJ, USA;2. Evander Gold Mine, Harmony Gold Mining Co., Ltd. , Evander, Republic of South Africa;3. Department of Geology , University of Toronto , Toronto, ON, Canada |
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| Abstract: | An in situ culturing device was incubated within a flowing borehole in a mafic sill at 1.474 km depth in Evander Au mine, South Africa. The device was designed to enrich methanogenic, Fe3 +-reducing and SO4 2 ?-reducing microorganisms using acetate, formate, methanol, Fe3 +-citrate and SO4 2 ? enriched agar and sand cartridges. At the end of the 33 day incubation geochemical analyses detected elevated H2, acetate, CH4 and Fe concentrations and depleted SO4 2 ? concentrations. 16S rDNA sequences and PLFA analyses revealed that the microbial community composition of the substrate-bearing cartridges were distinct from that of the original borehole water and the non-substrate-bearing control cartridge. 16S rDNA and dissimilatory sulfite reductase, dsrAB, gene sequences indicated the device successfully targeted SO4 2 ? reducing bacteria (SRB), which were not detected in the original borehole water. 16S rDNA sequences also revealed a shift in the microbial community from one relying on H2 based methanogenesis to one suggestive of H2 based acetogenesis supporting aceticlastic methanogenesis and SO4 2 ? reduction compatible with the subsurface lithoautotrophic hypothesis. |
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| Keywords: | acetogenesis Au mine dsrAB in situ microbial cultivation lithoautotrophic methanogenesis 16S rDNA SLiMEs SO4 2 ? reduction South Africa subsurface microbial ecosystem |
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