Microbial Abundance and Diversity at 0.8 to 3.6 Kilometers Beneath the Surface in the Witwatersrand Basin, South Africa
Abstract
Access to the Au mines of South Africa has provided us with an unparalleled opportunity to investigate the diversity and abundance of microbes from hydrologically restricted environments at depths up to 3.2 kilometers beneath the surface (kmbls.). Samples of highly pressurized, anaerobic water collected from freshly drilled bore holes into fault or dyke structures ranged in temperature from 32o to 60oC, in salinity from 0.2% to 2.5% and in pH from 7.2 to 10. Flow cytometry analyses of 21 samples amended with a fluorescent DNA stain yielded microbial concentrations ranging from <5{x}103 (detection limit) to 5{x}105 cellsml. The cell concentrations for half of these samples were below the detection limit and those of all the samples collected at 3.2 kmbls. were below detection. Fluorescent, forward and side scatter intensities indicate that the remaining samples contain one or two morphotypes. These values contrast with water samples from subsurface, dammed water pockets or service water where the cell concentrations range from 5{x}104 to 2.5{x}106 cellsml and as many as three morphotypes can be readily distinguished. Thermophilic enrichments suggest that some of these morphotypes are cultivable under conditions that are comparable to the environment. The apparent lack of cells in some of the water samples may reflect a combination of the thermal history of the basin, the origin of the fluid and the isolation of some of the fractures.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2001
- Bibcode:
- 2001AGUFM.B22D0183H
- Keywords:
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- 0400 BIOGEOSCIENCES