Dissimilatory reduction of Fe(III) and other electron acceptors by a Thermus isolate
- New Mexico Inst. of Mining and Technology, Socorro, NM (United States). Dept. of Biology
- Pacific Northwest National Lab., Richland, WA (United States)
- Princeton Univ., NJ (United States). Dept. of Geosciences; and others
A thermophilic bacterium that can use O{sub 2}, NO{sub 3}{sup {minus}}, Fe(III), and S{sup 0} as terminal electron acceptors for growth was isolated from groundwater sampled at a 3.2-km depth in a South African gold mine. This organism, designated SA-01, clustered most closely with members of the genus Thermus, as determined by 16S rRNA gene (rDNA) sequence analysis. The 16S rDNA sequence of SA-01 was >98% similar to that of Thermus strain NMX2 A.1, which was previously isolated by other investigators from a thermal spring in New Mexico. Strain NMX2 A.1 was also able to reduce Fe(III) and other electron acceptors. Neither SA-01 nor NMX2 A.1 grew fermentatively, i.e., addition of an external electron acceptor was required for anaerobic growth. Thermus strain SA-01 reduced soluble Fe(III) complexed with citrate or nitrilotriacetic acid (NTA); however, it could reduce only relatively small quantities of hydrous ferric oxide except when the humic acid analog 2,6-anthraquinone disulfonate was added as an electron shuttle, in which case 10 mM Fe(III) was reduced. Fe(III)-NTA was reduced quantitatively to Fe(II); reduction of Fe(III)-NTA was coupled to the oxidation of lactate and supported growth through three consecutive transfers. Suspensions of Thermus strain SA-01 cells also reduced Mn(IV), Co(III)-EDTA, Cr(VI), and U(VI). Mn(IV)-oxide was reduce in the presence of either lactate or H{sub 2}. Both strains were also able to mineralize NTA to CO{sub 2} and to couple its oxidation to Fe(III) reduction and growth. The optimum temperature for growth and Fe(III) reduction by Thermus strains SA-01 and NMX2 A.1 is approximately 65 C; their optimum pH is 6.5 to 7.0. This is the first report of a Thermus sp. being able to couple the oxidation of organic compounds to the reduction of Fe, Mn, or S.
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- FG03-93ER61683; FG02-94ER61821; AC06-76RL01830
- OSTI ID:
- 335360
- Journal Information:
- Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 3 Vol. 65; ISSN 0099-2240; ISSN AEMIDF
- Country of Publication:
- United States
- Language:
- English
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