AEROBIC OXIDATION OF HYDROGEN-SULFIDE BY THIOBACILLUS-DENITRIFICANS

It has been demonstrated that Thiobacillus denitrificans may be readily cultured aerobically in batch and continuous flow reactors on H//2S(g) under sulfide limiting conditions. Under these conditions sulfide concentrations in the culture medium were less than 1 mu M resulting in very low concentrations of H//2S in the reactor outlet gas. Biomass yield was not affected by steady state oxygen concentration in the range of 45 mu M-150 mu M. Biomass yield was also observed to be essentially independent of specific growth rate in the range of 0. 030-0. 053 h** minus **1. Maximum loading of the biomass for H//2S oxidation under aerobic conditions was observed to be 15. 1-20. 9 mmol/ h/g biomass which is much higher than previously reported for anaerobic conditions. Other aspects of the stoichiometry of aerobic H//2S oxidation are also reported.