In situ enrichment of a diverse community of bacteria from a 4-5 km deep fault zone in South Africa

Ellen Trimarco, David Balkwill, Mark Davidson, Tullis C. Onstott

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

The extreme environment of South Africa's ultra-deep gold mines offers an opportunity to discover novel microorganisms (e.g., Alkaliphilus transvaalensis), including extremophiles that may provide insight into the origins of life on earth and offer industrial applications because of their thermophilic enzymatic properties. This study employed culture-independent methods to examine the bacterial diversity in water (T = 55° C, pH = 9, Cl- = 1000 ppm and age = 4-53 Ma) emanating from an exploration borehole in a South African Au mine that intersected a quartzite-hosted fault at 3.3 km below land surface. The more adhesive strains of sulfate reducing bacteria were effectively selected and enriched from the planktonic community by forcing water from a flowing borehole through a sand/agar cartridge that was installed within the borehole. The cartridge's agar contained sulfate and lactate that diffused from the agar into the cartridge. DNA was extracted from the sand, after which a bacterial 16S rDNA gene clone library was generated. Analysis of clone sequences indicated that the groundwater bacterial community was quite diverse, including members of the α-, β-, and γ-Proteobacteria (20%), Actinobacteria (6%), Firmicutes (57%), Chloroflexi (3%), and Deinococcus-Thermus (14%) phyla. One of the most frequently detected clone types was associated with Desulfotomaculum (a known SRB). Another predominant clone type was closely related to Meiothermus cerbereus. A proportion of Proteobacteria clones were closely related to Ralstonia, Alishewanella, Hydrogenophaga, or Methylobacterium species. Some of the Firmicutes clones were closely related to Alkaliphilus transvaalensis, which was isolated from a nearby South African Au mine, or to Clostridium thermocellum. Of the total 21 OTUs identified from the cartridge sand, 6 most likely represent novel species of Firmicutes given their dissimilarity to other 16S rDNA sequences in the GenBank database.

Original languageEnglish (US)
Pages (from-to)463-473
Number of pages11
JournalHandbook of Environmental Chemistry, Volume 5: Water Pollution
Volume23
Issue number6
DOIs
StatePublished - Sep 1 2006

All Science Journal Classification (ASJC) codes

  • Earth and Planetary Sciences (miscellaneous)
  • Microbiology
  • Environmental Science(all)
  • Environmental Chemistry

Keywords

  • 16S rDNA
  • Groundwater
  • Sulfate reduction

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