A heterotrophic microorganism was isolated from sewage sludge, it was identified as Rhodotorula sp. R30. Its optimum pH for growth was 3-7, but it can stand the acidity of pH 2.5-1.5. The optimum temperature was 28 degrees C. When R30 was inoculated in the medium containing dissolved organic matter derived from sewage sludge and incubated for 96 h, dissolved organic carbon in the medium declined from 1485 mg/L to 345 mg/L, and the yeast number was 4.8 x 10(7) mL(-1). It was found through the batch trial that the period of bioleaching could be apparently shorted to 4 days if R30 was inoculated in the bioleaching system. Furthermore, the removal efficiency of Cr in sewage sludge could be enhanced by 39% with compared to the control without inoculating R30.