Effect of acetylene on nitrous oxide reduction and sulfide oxidation in batch and gradient cultures of Thiobacillus denitrificans

Article Abstract:

Anaerobic enrichment cultures yielded a bacterium tentatively identified as Thiobacillus denitrificans subsp ACN20. Batch cultures under denitrifying conditions showed a stepwise oxidation of hydrogen sulfide, with the formation of elemental sulfur, which was further oxidized to sulfate. Gradient cultures oxidized hydrogen sulfide directly to sulfate. The presence of ethylene in both batch and gradient cultures inhibited the oxidation of elemental sulfur, which was explained by inhibition of sulfate reductase. Reduction of dinitrogen oxide was detected both in the presence and absence of ethylene.

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Leaching of zinc sulfide by Thiobacillus ferrooxidans: bacterial oxidation of the sulfur product layer increases the rate of zinc sulfide dissolution at high concentrations of ferrous ions

Article Abstract:

Leaching of zinc sulfide, sphalerite, has been studied both with Thiobacillus ferrooxidans and without it where concentrations of ferrous ions are high. Results indicate bacterial oxidation of the sulfur product layer increases the rate of zinc sulfide dissolution. It appears that T. ferrooxidans oxidizes the sulfur formed on the particle surface and removes a barrier to ferrous ion diffusion. This is related to remedication of sites of acid maine drainage and to extraction of metals from sulfide ores.

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Denitrification by the fungus Cylindrocarpon tonkinense: anaerobic cell growth and two isozyme forms of cytochrome P-450nor

Article Abstract:

Analysis of the denitrification system of the fungus Cylindrocarpon tonkinense reveals the occurrence of distinct cell growth along with nitrite-dependent N2O formation. Respiration inhibitors suppress the N2O formation and/or cell growth, while ammonium ions exert no influence on these processes. Examination of purified Nor activity indicates that the activity depends on two isozymes of cytochrome P-405nor. Characteristics of these enzymes are compared.

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