Reclassification of some species of Thiobacillus to the newly designated genera Acidithiobacillus gen. nov., Halothiobacillus gen. nov and Thermithiobacillus gen. nov.

The species of the genus 'Thiobacillus' fall into the alpha-, beta- and gam ma-subclasses of the Proteobacteria, the type species Thiobacillus thioparu s being located in the beta-subclass. 'Thiobacillus' species exhibit almost as much diversity in DNA composition and physiology as is found collective ly in all other proteobacterial composition and physiology as Is found coll ectively In all other proteobacterial groups. On the basis of physiological characters and 16S rRNA gene sequence comparisons, eight of the existing T hiobacillus species are proposed for reassignment to three newly designated genera within the gamma-subclass of the Proteobacteria, namely Acidithioba cillus, Halothiobacillus and Thermithiobacillus.