Oxidation of hydrogen sulfide by continuous cultures of <i>Thiobacillus denitrificans</i>

Abstract

Thiobacillus denitrijicans is a strictly autotrophic and facultative anaerobe first described in detail by Baalsrud and Baalsrud.'Under anaerobic conditions nitrate may be used as a terminal electron acceptor with reduction to elemental nitrogen.Thiosulfate, elemental sulfur, and sulfide may be utilized as energy sources with oxidation to sulfate; however, sulfide is an inhibitory substrate.Timmer-ten-Hoor' demonstrated that T. denitrijicans will grow on sulfide (Na2S) as an energy source if sulfide is used as the growth limiting factor in a chemostat.Under these conditions the concentration of sulfide in the culture is maintained at very low levels.Growth of T. denitr$cans on H,S(g) has been demonstrated by Sublette and Sylvester3 who also proposed a process for the microbial desulfurization of natural gas.The stoichiometry of the anaerobic oxidation of H2S in batch reactors was reported and stable reactor operation demonstrated at reactor loadings as high as 4-5 mmol H2S oxidized/h/g biomass.Maximum loading was estimated at 5.4-7.6 mmol H,S/h/g biomass under sulfide limiting condition^.^