Thiobacillus is a genus of Gram-negative Betaproteobacteria. Thiobacilus thioparus is the type species of the genus, and the type strain thereof is the StarkeyT strain, isolated by Robert Starkey in the 1930s from a field at Rutgers University in the United States of America. While over 30 "species" have been named in this genus since it was defined by Martinus Beijerinck in 1904 (the first strain was observed by the biological oceanographer Alexander Nathansohn in 1902 - likely what we would now call Halothiobacillus neapolitanus), most names were never validly or effectively published. The remainder were either reclassified into Paracoccus, Starkeya (both in the Alphaproteobacteria); Sulfuriferula, Annwoodia, Thiomonas (in the Betaproteobacteria); Halothiobacillus, Guyparkeria (in the Gammaproteobacteria), or Thermithiobacillus or Acidithiobacillus (in the Acidithiobacillia). The very loosely defined "species" Thiobacillus trautweinii was where sulfur oxidising heterotrophs and chemolithoheterotrophs were assigned in the 1910-1960s era, most of which were probably Pseudomonas species. Many species named in this genus were never deposited in service collections and have been lost.
All species are obligate autotrophs (using the transaldolase form of the Calvin-Benson-Bassham cycle) using elementary sulfur, thiosulfate or polythionates as energy sources - the former Thiobacillus aquaesulis can grow weakly on complex media as a heterotroph but has been reclassified to Annwoodia aquaesulis. Some strains (E6 and Tk-m) of the type species Thiobacillus thioparus can use the sulfur from dimethylsulfide, dimethyldisulfide or carbon disulfide to support autotrophic growth - they oxidise the carbon from these species into carbon dioxide and assimilate it. Sulfur oxidation is achieved via the Kelly-Trudinger pathway.
- Thiobacillus versutus to Paracoccus
- Thiobacillus acidophilus to Acidiphilium
- Thiobacillus intermedius, Thiobacillus perometabolis, Thiobacillus thermosulfatus, and Thiobacilus cuprinus to Thiomonas
- Thiobacillus thiooxidans, Thiobacillus ferrooxidans, Thiobacillus caldus, and Thiobacillus albertensis to Acidithiobacillus
- Thiobacillus aquaesulis to Annwoodia aquaesulis.
- Thiobacillus neapolitanus to Halothiobacillus
- Thiobacillus thyasiris to Thiomicrospira thyasirae
- Thiobacillus hydrothermalis and Thiobacillus halophilus firstly to Halothiobacillus and later to Guyparkeria
- Thiobacillus tepidarius to Thermithiobacillus
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- Boden R (2017). "115 years of sulfur metabolism". FEMS Microbiology Letters. 364: fnx043. doi:10.1093/femsle/fnx043.
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- Kelly DP; Wood AP (2000). "Reclassification of some species of Thiobacillus to the newly designated genera Acidithiobacillus gen. nov., Halothiobacillus gen. nov. and Thermithiobacillus gen. nov". International Journal of Systematic and Evolutionary Microbiology. 50: 511–516. doi:10.1099/00207713-50-2-511. PMID 10758854. Retrieved 19 December 2015.
- Boden R (2017). "Reclassification of Halothiobacillus hydrothermalis and Halothiobacillus halophilus to Guyparkeria gen. nov. in the Thioalkalibacteraceae fam. nov., with emended descriptions of the genus Halothiobacillus and family Halothiobacillaceae". International Journal of Systematic and Evolutionary Microbiology. 67: 3919–3928. doi:10.1099/ijsem.0.002222. PMID 28884673. Retrieved 9 December 2017.
- Kelly DP; WoodAP (1993). "Reclassification of Thiobacillus thyasiris as Thiomicrospira thyasirae, new combination, an organism exhibiting pleomorphism in response to environmental conditions". Archives of Microbiology. 159: 45–47. doi:10.1007/BF00244262.