Electrochemical cultivation of Thiobacillus ferrooxidans by potential control

An iron oxidizing bacterium, Thiobacillus ferrooxidans can grow by oxidation of Fe(II) to Fe(III). Electrochemical regeneration of Fe(II) from Fe(III) can supply the growth energy for the bacterium. Electrochemical cultivation of T. ferrooxidans was carried out by the potential control method, The electrochemical regeneration occurred below 0.5 V vs, Ag/AgCl. The regenerated Fe(II) was consumed by the bacterium, which was observed by the cyclicvoltammetry of the soluble iron in the presence of the bacterium. The bacterium can be cultivated below the applied potential of 0.5 V. The bacterial growth rate increased at more negative potential in the range of 0.5 to 0 V. The growth rate depended on the reduction current at the applied potential range from 0 to -0.6 V. Hydrogen evolved at potentials more negative than -0.6 V. The bacterial growth rate was reflected by the electrochemical regeneration rates of Fe(II) which was determined by the rotatory ring-disk method. The potential control method, which can control the electrochemical reaction, would achieve a more efficient cultivation of the bacterium than the current control method which can waste current through the side reaction of hydrogen evolution. (C) 1997 Elsevier Science S.A.