Thiobacillus 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,[1][2] (the first strain was observed by the biological oceanographer Alexander Nathansohn in 1902 - likely what we would now call Halothiobacillus neapolitanus[3]), 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).
[4][3] All species are obligate autotrophs[1][2][3] (using the transaldolase form of the Calvin-Benson-Bassham cycle[4]) 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.
As a result of 16S ribosomal RNA sequence analysis, many members of Thiobacillus have been reassigned.