Thiobacillus denitrificans
Classification
Species
Description and Significance
Thiobacillus denitrificans is short rod-shaped (0.5×1.0-3.0 um), Gram-negative, obligately chemolithoautotrophic, and a member of the beta- subclass of the Proteobacteria. Different from many known chemolithotrophic sulfur-oxidizing bacteria (such as Acidithiobacillus ferrooxidans) which are strictly aerobic, T. denitrificans grows as a facultatively anaerobic chemolithotroph, coupling the oxidation of inorganic sulfur compounds to the reduction of nitrate, nitrite and other oxidized nitrogen compounds to dinitrogen. The optimum conditions for denitrification are pH 6.85 at 32.8°C, while the optimal growth conditions are pH 6.90 at 29.5°C. Found in soil, mud, freshwater- and marine sediments and also in domestic sewage and industrial waste-treatment lagoons and digestion tanks, especially under anoxic conditions.
T. denitrificans can remediate natural groundwater and engineered water treatment systems by removing excess nitrate. It also indirectly helps with the removal/absorbance of heavy metals and radionuclides (e.g., uranium).
T. denitrificans is one of the best studied of the very few obligately chemolithoautotrophic species which can couple denitrification with sulfur-compound oxidation.
