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Applied and Environmental Microbiology, June 1999, p. 2300-2306, Vol. 65, No. 6
Department of Botany and Microbiology and
Institute for Energy and the Environment, University of Oklahoma,
Norman, Oklahoma 73019,1 and Department
of Civil and Environmental Engineering, Massachusetts Institute of
Technology, Cambridge, Massachusetts 021392
Received 9 October 1998/Accepted 15 March 1999
We examined the relative roles of acetogenic and sulfate-reducing
bacteria in H2 consumption in a previously characterized subsurface sandstone ecosystem. Enrichment cultures originally inoculated with ground sandstone material obtained from a Cretaceous formation in central New Mexico were grown with hydrogen in a mineral
medium supplemented with 0.02% yeast extract. Sulfate reduction and
acetogenesis occurred in these cultures, and the two most abundant
organisms carrying out the reactions were isolated. Based on 16S rRNA
analysis data and on substrate utilization patterns, these organisms
were named Desulfomicrobium hypogeium sp. nov. and
Acetobacterium psammolithicum sp. nov. The steady-state
H2 concentrations measured in sandstone-sediment slurries
(threshold concentration, 5 nM), in pure cultures of sulfate reducers
(threshold concentration, 2 nM), and in pure cultures of acetogens
(threshold concentrations 195 to 414 nM) suggest that sulfate reduction
is the dominant terminal electron-accepting process in the ecosystem examined. In an experiment in which direct competition for
H2 between D. hypogeium and A. psammolithicum was examined, sulfate reduction was the dominant process.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Characterization of Two Subsurface
H2-Utilizing Bacteria, Desulfomicrobium
hypogeium sp. nov. and Acetobacterium psammolithicum
sp. nov., and Their Ecological Roles
and
*
Corresponding author. Mailing address: Department of
Botany and Microbiology and Institute for Energy and the Environment, University of Oklahoma, Norman, OK 73019. Phone: (405) 325-0437. Fax:
(405) 325-7619. E-mail: krumholz{at}ou.edu.
Present address: School of Civil and Structural Engineering,
Nanyang Technological University, Singapore 639798.
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