Investigation of lead bioimmobilization and transformation by Penicillium oxalicum SL2

Fungi Penicillium oxalicum SL2 was applied for Pb2+ bioremediation in aqueous solution in this study. After 7 days of incubation at different initial concentrations of Pb2+ (0, 100, 500 and 2500 mg L−1), most of Pb2+ were removed (90, 98.3, and 86.2%), the maximum Pb content in mycelium reached about 155.6 mg g−1 dw. Meanwhile, the formation of extracellular secondary minerals and intracellular Pb-complex were observed and identified, the speciation of Pb in mycelium was also detected by X-ray absorption near-edge structure (XANES) spectroscopy, i.e., Pb-oxalate, Pb-citrate, Pb-hydrogen phosphate and Pb-glutathione analogues. In addition, content of glutathione and oxidized glutathione was increased under the exposure of Pb2+, which implied that glutathione might play a key role in Pb immobilization and detoxification in P. oxalicum SL2. This study elucidated partial mechanisms of Pb immobilization and speciation transformation of this strain, providing an alternative biomaterial in the bioremediation of Pb-contaminated wastewater.