Iron and carbon metabolism by a mineral-oxidizing Alicyclobacillus-like bacterium
A novel iron-oxidizing, moderately thermophilic, acidophilic bacterium (strain “GSM”) was isolated from mineral spoil taken from a gold mine in Montana. Biomolecular analysis showed that it was most closely related to Alicyclobacillus tolerans, although the two bacteria differed in some key respects, including the absence (in strain GSM) of ϖ-alicyclic fatty acids and in their chromosomal base compositions. Isolate GSM was able to grow in oxygen-free media using ferric iron as terminal electron acceptor confirming that it was a facultative anaerobe, a trait not previously described in Alicyclobacillus spp.. The acidophile used both organic and inorganic sources of energy and carbon, although growth and iron oxidation by isolate GSM was uncoupled in media that contained both fructose and ferrous iron. Fructose utilization suppressed iron oxidation, and oxidation of ferrous iron occurred only when fructose was depleted. In contrast, fructose catabolism was suppressed when bacteria were harvested while actively oxidizing iron, suggesting that both ferrous iron- and fructose-oxidation are inducible in this acidophile. Isolate GSM accelerated the oxidative dissolution of pyrite in liquid media either free of, or amended with, organic carbon, although redox potentials were significantly different in these media. The potential of this isolate for commercial mineral processing is discussed.
KeywordsAcidophile Alicyclobacillus Firmicute Iron oxidation Iron reduction Mixotroph Pyrite
AY is grateful to the Universiti Teknologi Malaysia for providing and research studentship, and DBJ to the Royal Society, UK, for providing an Industrial Research Fellowship.
- Clark DA, Norris PR (1996) Acidimicrobium ferrooxidans gen. nov., sp. nov.: mixed-culture ferrous iron oxidation with Sulfobacillus species. Microbiology 142:785–790Google Scholar
- Ehrlich HL (2002) Geomicrobiology, 4th edn. Taylor and Francis, New YorkGoogle Scholar
- Germida JJ (1985) Modified sulfur-containing media for studying sulfur-oxidizing microorganisms. In: Caldwell DE, Brierley JA, Brierley CL (eds) Planetary ecology. van Nostrand Reinhold, New York, pp 333–344Google Scholar
- Goto K, Mochida K, Asahara M, Suzuki M, Kasai H, Yokota A (2003) Alicyclobacillus pomorum sp. nov., a novel thermo-acidophilic, endospore-forming bacterium that does not possess a-alicyclic fatty acids, and emended description of the genus Alicyclobacillus. Int J Syst Evol Microbiol 53:1537–1544PubMedCrossRefGoogle Scholar
- Johnson DB (2007) Physiology and ecology of acidophilic microorganisms. In: Gerday C, Glansdorff N (eds) Physiology and biochemistry of extremophiles. ASM, Washington, DC, pp 257–270Google Scholar
- Johnson DB, Body DA, Bridge TAM, Bruhn DF, Roberto FF (2001) Biodiversity of acidophilic moderate thermophiles isolated from two sites in Yellowstone National Park, and their roles in the dissimilatory oxido-reduction of iron. In: Reysenbach AL, Voytek A (eds) Thermophiles: biodiversity, ecology and evolution. Kluwer/Plenum, New York, pp 23–39Google Scholar
- Johnson DB, Bacelar-Nicolau P, Okibe N, Thomas A, Hallberg KB (2007) Characteristics of Ferrimicrobium acidiphilum gen. nov., sp. nov., and Ferrithrix thermotolerans gen. nov., sp. nov.: heterotrophic iron-oxidizing, extremely acidophilic Actinobacteria. Int J Syst Evol Microbiol (submitted)Google Scholar
- Karavaiko GI et al (2005) Reclassification of ‘Sulfobacillus thermosulfidooxidans subsp. thermotolerans’ strain K1 as Alicyclobacillus tolerans sp. nov. and Sulfobacillus disulfidooxidans Dufresne et al. 1996 as Alicyclobacillus disulfidooxidans comb. nov., and emended description of the genus Alicyclobacillus. Int J Syst Evol Microbiol 55:941–947PubMedCrossRefGoogle Scholar
- Norris PR, Ingledew WJ (1992) Acidophilic bacteria: adaptations and applications. In: Herbert RA, Sharp RJ (eds) Molecular biology and biotechnology of extremophiles. Royal Society for Chemistry, Cambridge, pp 121–131Google Scholar
- Wilson K (1987) Preparation of genomic DNA from bacteria. In: Ausubel FM, Brent R, Kingston RE, Moore DD, Seidman JA, Struhl K (eds) Current protocols in molecular biology. Green & Wiley Interscience, New York, pp 2.4.1–2.4.5Google Scholar
- Wisotzkey JD, Jurtshuk P, Fox GE, Deinhard G, Poralla K (1992) Comparative sequence analyses on the 16S ribosomal-RNA (rDNA) of Bacillus acidocaldarius, Bacillus acidoterrestris, and Bacillus cycloheptanicus and proposal for creation of a new genus, Alicyclobacillus gen. nov. Int J Syst Bacteriol 42:263–269PubMedCrossRefGoogle Scholar