The Effect of Ferrous Iron Addition during Tetrathionate Utilisation by Some Sulfobacillus Species

Ferrous sulfate was added to batch cultures ofSulfobacillus (Sb.) acidophilus,Sb. thermosulfidooxidansandSb. sibiricusduring growth on tetrathionate. Soluble ferrous ion and polythionate concentrations were used as a measure of substrate utilisation.Sb. thermosulfidooxidansswitched from utilising polythionates to exclusively oxidising ferrous ions, only then oxidising the remainder of the polythionates.Sb. sibiricusandSb. acidophilusdid not cease polythionate oxidation but utilised both substrates concurrently after ferrous ion addition. None of the cultures tested exhibited preferential polythionate utilisation, even though they were utilising polythionate prior to the addition of ferrous ions.