[Studies on reduction of hexavalent chromium by fungi]

Several fungal strain, isolated from activated sludge, sewage and soil, were able to grow in the medium containing 300-500 mg/L K2Cr2O7, and strain BS-1 was capable of resistance to K2Cr2O7 up to 900 mg/L. After 4-6 d growing of the strain BS-1 and other 3 strains in the liquid medium added 200 mg/L K2Cr2O7, the Cr(VI) content of the medium disappeared completely. These strain were identified as Penicillium sp. BS-1, BS-3, Aspergillus niger BR-4, Aspergillus flavus BX-1 respectively. The results from the detection of the fungal culture by UV-absorbance spectrum and chemical analysis showed that high-toxic Cr(VI) was reduced to lesstoxic Cr(III). Reaction conditions and effectors of Cr(VI) reduction by intact cells of Penicillium sp. BS-1 were studied. The optimum temperature was 30 degrees C, the optimum pH was 7.0. Addition of glucose (0.25%) enhanced Cr(VI) reduction, but high concentrations of Cr(VI) inhibited the reduction of Cr(VI) to Cr(III).