Extension of logarithmic growth of Thiobacillus ferrooxidans using potential controlled electrochemical cultivation system

In this study, we demonstrated that the logarithmic growth of Thiobacillus ferrooxidans could be maintained under conditions of efficient Fe(II) regen eration with the potential controlled reduction of Fe(III) and sufficient a eration. The potential controlled electrolysis produced a high efficiency ( 80%) reduction of Fe(III). The use of a glassy microbubbler showed that it was possible to maintain a dissolved oxygen concentration in the medium ade quate for a 7.0 x 10(9) cells/cm(3) cell suspension. Using this system, the logarithmic growth of T. ferrooxidans was maintained for 4 days reaching a final cell density of 1 x 10(10) cells/cm(3) within 6 days. This concentra tion was a 50-fold increase over the conventional batch culture.