Thermophilic, anaerobic bacteria isolated from a deepborehole in granite in Sweden.

Abstract

A borehole drilled to a total depth of 6779 m in granitic rock in Gravberg, Sweden, was sampled and examined for the presence ofanaerobic, thermophilic, fermenting bacteria and sulfate-reducing bacteria. Growth in enrichment cultures was obtained only from water samples collected from a specific sampling depth in the borehole (3500 m). The hole was cased down to a depth of 5278 m and open to the formation below that level. All the water below 2000 m in depth standing in the borehole at the time of sampling must have entered at the 5278-m level or below, during a prior pumping operation. A strong salinity stratification certifies that no major amount of vertical mixing had taken place. The depth from which bacteria could be enriched was that of a pronounced local minimum of salinity. (9,10). However, a sporeforming, thermophilic, sulfate-reducing bacterium, Desulfotomaculum geothermicum, has been isolated from anoxic geothermal groundwater from a depth of 2500 m with an in situ temperature of 580C (11).In the present study, groundwater from a borehole in granitic rock with a maximum depth of6780 m was examined microbiologically. The deepest water sample accessible from this borehole was at a depth of 4100 m. Samples from the water column in the borehole were examined for the presence of thermophilic, fermenting bacteria and sulfate-reducing bacteria. Bacteria could be enriched only in samples from a distinct depth (3500 m), and these were fermentative; no sulfate-reducing bacteria were found. MATERIALS AND METHODS 1810The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Description of Thermoanaerobacter brockii subsp. lactiethylicus subsp. nov., Isolated from a Deep Subsurface French Oil Well, a Proposal To Reclassify Thermoanaerobacter finnii as Thermoanaerobacter brockii subsp. finnii comb. nov., and an Emended Description of Thermoanaerobacter brockii

“…To date, no formal characterization of fermentative bacteria isolated from such environments has been published, although short descriptions of strains SEBR 526ST and Gluc 1 have appeared previously (12,38). Our formal description of strain SEBR 526ST obtained from an oil field in this paper extends the physiological diversity and taxonomic diversity of thermophiles found in deep subsurface environments.…”

“…Additional sequence alignment and evolutionary distance analyses performed with members of this hylum indicated that the closest relatives of strain SEBR 5268 were T. Jinnii, T. brockii, and strain Gluc 1 ( Table 1). Isolation of strain Gluc 1 has been described, but detailed characteristics of this isolate have not been published yet (38). The 16s rRNA sequence of strain Gluc 1 was obtained from the Ribosomal Database Project (21).…”

“…Furthermore, T. acetoethylicus does not use pyruvate and D-xylose, whereas strain SEBR 5268T does. Although strain Gluc 1, a partially characterized isolate obtained from a 6,779-m-deep Swedish bore hole, is morphologically and phylogenetically similar to strain SEBR 5268*, it produces ethanol, lactate, CO,, and H, from fermentation of glucose (38), whereas strain SEBR 5268T produces acetate in addition to these products. The phenotypically most closely related Thermoanaerobacter species is T. finnii.…”

How Deep Can Surface Signals Be Traced in the Critical Zone? Merging Biodiversity with Biogeochemistry Research in a Central German Muschelkalk Landscape

“…Resulting, to some extent, from a decreasing availability of mineralizable organic carbon, microbial abundance, diversity, and activity in the vadose zone are lower than in surface soils but may increase again within the capillary fringe and the groundwater zone. (Holden and Fierer, 2005) Nevertheless, living microorganisms involved in the reduction of nitrate, sulfate and iron as well as acetogenesis, and methanogenesis have been reported from groundwater within granitic bedrock at depths of up to 978 m (Pedersen, 1997;Hallbeck and Pedersen, 2008) while the maximum depth of terrestrial subsurface drilling from which living organisms have been reported is 5.3 km (Szewzyk et al, 1994). Progress will require not just a cataloging of subsurface life, but an understanding of how the biodiversity of the subsurface transforms the mineralogy, shapes its physical and trophic environment, and influences the gases, water, solutes, and colloids moving through the CZ.…”

Radioisotopic, Culture-Based, and Oligonucleotide Microchip Analyses of Thermophilic Microbial Communities in a Continental High-Temperature Petroleum Reservoir

“…For a very long time, the mesophilic microbes that were recovered from the earth's crust were suspected to be surface contaminants. Increasing evidence of microbial populations thriving in deep geological formations has been given by recent key discoveries (39,51,53). Among these peculiar habitats, oil fields occurring at significant subsurface depth and, consequently, characterized by a high in situ temperature represent unique biotopes that constitute ecological niches providing suitable conditions to support thermophilic organisms (50).…”