Isolation and Characterization of Metal-Reducing Thermoanaerobacter Strains from Deep Subsurface Environments of the Piceance Basin, Colorado

Abstract

Five bacterial strains were isolated from anaerobic enrichment cultures that had originated from inoculations with samples collected from the deep subsurface environments of the millions-of-years-old, geologically and hydrologically isolated Piceance Basin in Colorado. Small-subunit rRNA gene-based analyses indicated that all of these bacteria were closely related to Thermoanaerobacter ethanolicus, with similarities of 99.4 to 99.5%. Three isolates (X513, X514, and X561) from the five bacterial strains were used to examine physiological characteristics. These thermophilic bacteria were able to use acetate, glucose, hydrogen, lactate, pyruvate, succinate, and xylose as electron donors while reducing Fe(III), cobalt(III), chromium(VI), manganese(IV), and uranium(VI) at 60°C. One of the isolates (X514) was also able to utilize hydrogen as an electron donor for Fe(III) reduction. These bacteria exhibited diverse mineral precipitation capabilities, including the formation of magnetite (Fe 3 O 4 ), siderite (FeCO 3 ), rhodochrosite (MnCO 3 ), and uraninite (UO 2 ). The gas composition of the incubation headspace and the ionic composition of the incubation medium exerted profound influences on the types of minerals formed. The susceptibility of the thermophilic Fe(III)-reducing cultures to metabolic inhibitors specific for ferric reductase, hydrogenase, and electron transport indicated that iron reduction by these bacteria is an enzymatic process.

Single gene insertion drives bioalcohol production by a thermophilic archaeon

“…The genes were obtained from the thermophilic bacterium Thermoanaerobacter strain X514, which grows near 70°C (16). These genes were inserted, individually and in combination, into the P. furiosus genome (17), yielding strain E (containing adhE), strain A (containing adhA), and strain EA (containing adhE and adhA; Fig.…”

“…P. furiosus strain COM1 (17) served as the parent strain for genetic manipulations for the heterologous expression of the bifunctional aldehyde/alcohol dehydrogenase AdhE (Teth514 0627; GeneID: 5876124) and the primary alcohol dehydrogenase AdhA (Teth514 0564; GeneID 5877753) from Thermoanaerobacter strain X514 (16). Genomic DNA was isolated according to Zhou et al (32).…”

U(VI) reduction by spores of Clostridium acetobutylicum

“…, extremophiles (e.g., Thermoanaerobacter spp. (Roh et al, 2002) and Pyrobaculum islandicum (Kashefi and Lovley, 2000)) as well as Gram-positive non-spore-forming bacteria (e.g., Thermoterrabacterium sp.) (Khijniak et al, 2005).…”

Gold in Devono-Carboniferous red beds of northern Britain

“…These temperatures are consistent with burial of no more than 3 km, representing diagenesis rather than metamorphism. Experimental reduction of metals by Fe(III) reducers at temperatures of 60-100°C shows that microbial activity could concentrate metals in this shallow burial realm (Kashefi & Lovley 2000;Roh et al 2002).…”