Microorganisms from deep, high temperature sandstones: constraints on microbial colonization

Abstract

Cores were collected from Late Cretaceous and Early Tertiary rocks in the Piceance Basin of western Colorado, USA, to investigate the origins of subsurface microorganisms under geological conditions likely to constrain microbial transport and survival. The sampled strata from 856–862, 1996–1997 and 2091–2096 m recorded peak paleotemperatures of 120–145°C from 40–5 million years ago, while present temperatures range from 43 to 85°C. Cores were analyzed for culturable anaerobic bacteria (Fe(III)‐ and Mn(IV)‐reducing bacteria, fermenters, sulfate reducers, nitrate reducers and methanogens), ester‐linked phospholipid fatty acid and selected enzyme and physiological activities. Measurable but low biomass (total phospholipid fatty acid) and anaerobic bacteria, primarily Fe(III) reducers and fermenters, were present in samples from the 856–862 m core. Cores from greater depths yielded only a single positive enrichment and lower biomass values. Methanogens and sulfate reducers were not detected in any of the samples nor were bacteria that could grow with methane and any added electron acceptors. 16S rRNA genes cloned from products of PCR amplification of DNA extracted from an 858 m, 65°C, Fe(III)‐reducing enrichment were most closely related to bacteria in the genus Desulfotomaculum, Gram‐positive, spore‐forming sulfate‐reducing bacteria. Assuming the maximum temperatures would have eliminated any entrained bacteria, these anaerobic microorganisms likely migrated into the shallower Wasatch formation within the last 5 million years. However, the deepest stratum sampled was hydrologically isolated and lacked any indication of microbial colonization by all biological measures. Hydrologic connection to the surface, high maximum temperatures and the presence of fractures are probably the primary factors that control distribution of microorganisms in these deep rock environments.

Microbial Growth under Supercritical CO 2

“…(34). Culture media were added to serum bottles and degassed with a stream of 100% CO 2 or 100% N 2 gas for 30 min prior to pressurization.…”

Desulfotomaculum spp. and related gram-positive sulfate-reducing bacteria in deep subsurface environments

“…Few studies of the microbial diversity of deep aquifers have been published, but deep water-bearing formations are potential ecological niches for Desulfotomaculum and Desulfosporosinus species (Colwell et al, 1997; Detmers et al, 2001, 2004; Stahl et al, 2002). Studies of a pristine aquifer have shown a presence of Desulfotomaculum spp.…”

Phylogeny and phylogeography of functional genes shared among seven terrestrial subsurface metagenomes reveal N-cycling and microbial evolutionary relationships

“…Geological tests have shown that microorganisms traveled through the less porous sandstones (8.5–20%) at Cerro Negro, New Mexico, USA over a distance of 100 m, at depth of ~300 m, in less than 3.4 million years via a ground water velocity of 0.1 m yr −1 (Walvoord et al, 1999). The microbial colonization of a low permeability sterilized sandstone (porosity of 1–12%) in the Piceance Basin, western Colorado, USA down to the depth of 860 m had occurred in less than 5 million years (Colwell et al, 1999). The microbial transport in fractured basement rocks is even less certain, as these rocks typically exhibit a bimodal hydraulic conductivity/porosity with fractures yielding water velocity of ~3 cm yr −1 , but comprising only 0.01% of the porosity, and a matrix porosity of ~1% yielding water velocity of ~0.003 cm yr −1 (Nordstrom et al, 1989).…”