Acidiferrobacter thiooxydans, gen. nov. sp. nov.; an acidophilic, thermo-tolerant, facultatively anaerobic iron- and sulfur-oxidizer of the family Ectothiorhodospiraceae
- 995 Downloads
A comprehensive physiological and phylogenetic characterisation was carried out of “Thiobacillus ferrooxidans” m-1, an acidophilic iron-oxidizing bacterium first described over 25 years ago. Phylogenetically, strain m-1 is a gammaproteobacterium, most closely related to alkaliphilic Ectothiorhodospira spp. and only distantly to iron-oxidizing acidithiobacilli. Physiological examination confirmed that strain m-1 can grow autotrophically not only by ferrous iron oxidation but also, in contrast to previous reports, by oxidation of elemental sulfur, sulfide and tetrathionate, using either oxygen or ferric iron as terminal electron acceptor. The bacterium was also found to be thermo-tolerant, growing optimally at 38°C and up to a maximum of 47°C. Growth in liquid media required an external osmotic potential of >2 bar, and was optimal at ~5 bar, though no growth occurred where the medium osmotic potential was close to that of sea water (~26 bar). From this, it was concluded that strain m-1 is a moderate osmophile. Strain m-1 was also shown to be diazotrophic and tolerant of elevated concentrations of many metals typically found in mine-impacted environments. On the basis of these data, m-1 is proposed as the type strain of a new genus and species of bacteria, Acidiferrobacter thiooxydans (DSM 2392, JCM 17358).
KeywordsAcidophile Diazotroph Iron oxidation Iron reduction Osmophile Sulfur oxidation Thermo-tolerance
The authors wish to acknowledge financial support for this work from the Biosciences, Environment and Agriculture Alliance (BEAA) between Bangor and Aberystwyth Universities and the European Union (FP7 project “Promine”). DBJ is grateful to the Royal Society for the provision of an Industrial Fellowship. The authors thank Dr. Tadayoshi Kanao, Okayama University Japan, for his contribution to the measurement of specific rates of iron oxidation and Professor Jean Euzéby for his willingness to share his expertise on nomenclature.
- Hallberg KB, Johnson DB (2007) Isolation, enumeration, growth, and preservation of acidophilic prokaryotes. In: Hurst CJ, Crawford RL, Garland JL, Lipson DA, Mills AL, Stetzenbach LD (eds) Manual of environmental microbiology, 3rd edn. American Society of Microbiology Press, Washington, DC, pp 1155–1165Google Scholar
- Imhoff JF (2006) The family Ectothiorhodospiraceae. In: Dworkin M, Falkow S, Rosenberg E, Schleifer KH, Stackebrandt E (eds) The prokaryotes: a handbook on the biology of bacteria, vol 6, 3rd edn. Springer, New York, pp 874–886Google Scholar
- Johnson DB, Hallberg KB (2008) Carbon, iron and sulfur metabolism in acidophilic micro-organisms. Adv Microb Physiol 54:202–256Google Scholar
- Johnson DB, Bacelar-Nicolau P, Okibe N, Thomas A, Hallberg KB (2009) 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 59:1082–1089PubMedCrossRefGoogle Scholar
- Mitchell D, Harneit K, Meyer G, Sand W, Stackebrandt E (2004) Systematic analysis of our culture collection for “genospecies” of Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Leptospirillum ferrooxidans. In: Ciminelli VST, Garcia O Jr (eds) Biohydrometallurgy: fundamentals, technology and sustainable development. Elsevier, Amsterdam, pp 1369–1378Google Scholar