Anaerobic Growth of Thiobacillus ferrooxidans

The obligately autotrophic acidophile Thiobacillus ferrooxidans was grown on elemental sulfur in anaerobic batch cultures, using ferric iron as an electron acceptor. During anaerobic growth, ferric iron present in the growth media was quantitatively reduced to ferrous iron. The doubling time in anaerobic cultures was approximately 24 h. Anaerobic growth did not occur in the absence of elemental sulfur or ferric iron. During growth, a linear relationship existed between the concentration of ferrous iron accumulated in the cultures and the cell density. The results suggest that ferric iron may be an important electron acceptor for the oxidation of sulfur compounds in acidic environments.