Identification and characterization of Acidithiobacillus ferrooxidans YY2 and its application in the biodesulfurization of coal.

The acidophilic Fe-oxidizing and S-oxidizing bacterium YY2 was isolated from the acid drainage of a coalmine. Based on morphological and physiological characteristics and phylogenetic analysis, it was identified as Acidithiobacillus ferrooxidans. Significant differences were observed in the oxidation efficiency and cell morphology when YY2 was cultured in 9K medium with ferrous ion (Fe(2+)), elemental sulfur (S(0)), and pyrite as the sole energy source. YY2 exhibited marked Fe(2+) oxidation activity; 44.2 g · L(-1) FeSO4 · 7H2O was completely oxidized in 30 h, but the rates of S(0) and pyrite oxidization were slower. After 20 days, the efficiencies of oxidizing 10 g · L(-1) S(0) and 10 g · L(-1) pyrite were approximately 9.6% and 20%, respectively. Cells cultured in pyrite as substrate secreted more extracellular polymeric substances than they did when cultured in Fe(2+) or S(0). Additionally, 75% total sulfur removal and 86% pyritic sulfur removal was achieved in a sequencing batch reactor of biodesulfurization of coal.