Bacteria; Firmicutes; Clostridia; Clostridiales; Clostridiales Family XVII. Incertae Sedis; Sulfobacillus
Description and Significance
S. thermosulfidooxidans was first isolated by in 1978 by Golovacheva and Karavaiko from a copper-zinc-pyrite deposit in Kazakhstan. S. thermosulfidooxidans has also been found in Acid Mine Drainage (AMD)(14)(15). It is a Gram-positive, non-motile, spore-forming, bacillus.(4) S. thermosulfidooxidans is thermophilic and acidophilic with a temperature range of 20-60°C and pH range of 1.5 – 5.5, however optimum growth occurs at approximately 50-55°C with a pH of 1.9 – 2.4.(4) There are three know strains of S. thermosulfidooxidans. These strains include S.thermosulfidooxidans str Cutipay, S. thermosulfidooxidans ST, and S. thermosulfidooxidans DSM 9293. S. thermosulfidooxidans is an important organism in the mining industry for is ability to oxidize Sulfur and Fe2+ which are necessary processes for Bioleaching which is a type of mining where microorganisms are used to remove metals from ore.(5)
A draft genome sequence has been created of S. thermosulfidooxidans str Cutipay using whole genome shotgun sequencing with a mixed technology method.(6) This strain has a genome assembly containing 3,862,012 bp.(6) The genome contains 3,600 genes including Sulfur and Carbon metabolizing enzymes.(6) Arsenic resistance arsRB operon was found which includes arsR regulator (codes for transcriptional regulator), arsB (codes for an arsenite efflux pump in the membrane), and arsC gene(codes for arsenate reductase)indicating an ability for arsenic resistance in this strain.(6)(7) Copper sensing genes copR and copS were found to be present in the genome in addition to gene cueR.(6) The presence of these three copper-resistance genes suggests that operon copAZ could also be present.(6)
Cell Structure, Metabolism and Life Cycle
S. thermosulfidooxidans form rod-shaped, non-motile cells that grow individually, in pairs, or as short chains.(4) Colonies are round and initially appear yellowish and shining then turning reddish-brown on media containing Fe2+.(4) When in a dormant state, S. thermosulfidooxidans can form an Endospore which can be located sub-terminally, terminally, or paracentrally.(4) All organisms in the genus Sulfobacillus have a mixotrophic metabolism meaning that they can exist as an autotroph or a heterotroph oxidizing sulfide minerals, Fe2+, S4O62-, S0, and S2O32- in the presence of some organic substrates.(4)(8) S. thermosulfidooxidans is also a facultative organotroph with the ability to get energy and carbon from organic compounds with or without the presence of oxygen.(4)(8)
S. thermosulfidooxidans is ecologically important for a mining process called Bioleaching.(9) Bioleaching is the process where microorganisms are used to extract metals from ores.(9) Rather than using the techniques of roasting or smelting to extract the metal which can be environmentally detrimental and costly, microbes are used in large-scale heap or tank aeration processes.(9)(10)(12)(13) During Pyrite leaching, S. thermosulfidooxidan can adhere to a mineral using an Exopolysaccharide(EPS) layer and it is within this layer that oxidation reactions occur most rapidly.(10) After attachment, the reactions for Pyrite bioleaching occur as follows:(9)
Next, with the help of Iron oxidizing bacteria, the next reaction occurs:
The presence of Thiosulfate oxidizing bacteria allow Thiosulfate to be turned into Sulfate.
The net reaction for the bioleaching of Pyrite is as follows:
Bioleaching can be very beneficial compared to traditional methods because it is more cost effective due to the simplification of the process, also it is more environmentally friendly because of the reduction in hazardous emissions that are associated with traditional methods and there is less disruption of the environment because the microorganisms are naturally occurring.(9) In addition to these benefits, the use of microorganisms reduces the need for intense process used to extract small amounts of metal from ore.(9) However, the process of bioleaching is very slow compared to traditional methods and in some cases can produce hazardous substances such as Sulfuric Acid and Heavy Metals which could cause the creation of Acid Mine Drainage.(9)
1. "Sulfobacillus Thermosulfidooxidans." NCBI. U.S. National Library of Medicine, n.d. Web. 23 Apr. 2014. <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=28034>.
2. "Representative." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 23 Apr. 2014. <http://www.ncbi.nlm.nih.gov/genome/11441>.
3. Golovacheva, and Karavaiko. "Result Filters." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 23 Apr. 2014. <http://www.ncbi.nlm.nih.gov/pubmed/101742>.
4. Bergey's Manual of Systematic Bacteriology. Ed. George M. Garrity, William B. Whitman, Paul De Vos, Dorothy Jones, Noel. R. Krieg, Wolfgang Ludwig, Fred A. Rainey, and Karl-Heinz Schleifer. 2nd ed. Vol. 3. New York: Springer, 2009. 1181-183. Print. The Firmicutes.
5. " Representative." National Center for Biotechnology Information. U.S. National Library of Medicine, n.d. Web. 24 Apr. 2014. <http://www.ncbi.nlm.nih.gov/genome/?term=sulfobacillus+thermosulfidooxidans>.
6. Travisany, Dante, Alex Di Genova, Andrea A. Bobadilla-Fazzini, Pillar Parada, and Alejandro Maass. "American Society for MicrobiologyJournal of Bacteriology." Draft Genome Sequence of the Sulfobacillus Thermosulfidooxidans Cutipay Strain, an Indigenous Bacterium Isolated from a Naturally Extreme Mining Environment in Northern Chile. Journal of Bacteriology, 2012. Web. 24 Apr. 2014. <http://jb.asm.org/content/194/22/6327.full#ref-9>.
7. "The Identification and Characterisation of the Arsenic Resistance Genes of the Gram-positive Bacterium, Sulfobacillus Thermosulfidooxidans VKM B-1269T." The Identification and Characterisation of the Arsenic Resistance Genes of the Gram-positive Bacterium, Sulfobacillus Thermosulfidooxidans VKM B-1269T. Stellenbosch Universitym, Mar. 2007. Web. 24 Apr. 2014. <http://hdl.handle.net/10019.1/19886>.
8. Slonczewski, Joan, and John Watkins. Foster. Microbiology: An Evolving Science. 2nd ed. New York: W.W. Norton, 2011. Print.
9. "Bioleaching." Wikipedia. Wikimedia Foundation, 23 Apr. 2014. Web. 29 Apr. 2014. <http://en.wikipedia.org/wiki/Bioleaching>.
10. Rawlings, Douglas E. "Characteristics and Adaptability of Iron- and Sulfur-oxidizing Microorganisms Used for the Recovery of Metals from Minerals and Their Concentrates." Microbial Cell Factories. BioMed Central Ltd, 06 May 2005. Web. 29 Apr. 2014. <http://www.microbialcellfactories.com/content/4/1/13>.
11. Dick, Gregory J., Anders F. Andersson, Brett J. Baker, Sheri L. Simmons, Brian C. Thomas, A. Pepper Yelton, and Jillian F. Banfield. "Community-wide Analysis of Microbial Genome Sequence Signatures." Genome Biology. BioMed Central Ltd, 21 Aug. 2009. Web. 30 Apr. 2014. <http://genomebiology.com/2009/10/8/r85>.
12. "Smelting." Wikipedia. Wikimedia Foundation, 25 Apr. 2014. Web. 30 Apr. 2014. <http://en.wikipedia.org/wiki/Smelting>.
13. "Roasting (metallurgy)." Wikipedia. Wikipedia foundation, 14 Jan. 2014. Web. 30 Apr. 2014 <http//http://en.wikipedia.org/wiki/Roasting_%28metallurgy%29>.
14. "Acid Mine Drainage." - MicrobeWiki. MicrobeWiki, n.d. Web. 30 Apr. 2014. <http://microbewiki.kenyon.edu/index.php/Acid_mine_drainage>.
15. "Acidophiles in Acid Mine Drainage." Wikipedia. Wikimedia Foundation, 30 Mar. 2014. Web. 30 Apr. 2014. <http://en.wikipedia.org/wiki/Acidophiles_in_acid_mine_drainage>.