Evaluation of lead tolerance and biosorption characteristics of fungi from dumpsite soils

Abstract

Lead (Pb) pollution is a major concern in many developing nations of the world. Hence, there is a need for the development of an environmentally safe and cost-effective method for the clean-up of contaminated environments. The present study investigated the tolerance of presumptively identified fungal species isolated from 5 different dumpsite soils to Pb concentrations 200, 400, 600, 800, 1000, 1500, 5000, and 10000 mg/L. The identity of strains exhibiting outstanding tolerance was confirmed using molecular technique, and their biosorption capacity at 10000 mg/L was evaluated. FTIR and SEM analyses were performed on the Pb2+ untreated and treated fungal biomasses. A total of 17 fungal isolates belonging to the genera Aspergillus Alternaria, Chrysosporium, and Penicillium were obtained. All the fungi were resistant to the test concentrations of Pb2+ except Chrysosporium sp. (at 5000 mg/L and 10000 mg/L) and Alternaria sp. (at 1500 mg/L, 5000 mg/L, and 10000 mg/L). Four isolates molecularly identified as A. awamori OP341445 and OP341446 and A. niger OP342447 and OP341448 recorded outstanding tolerance (> 1). Biosorption capacity was at its peak on day 5 except in OP34148, day 10 with a value of 97.82 mg/g. The Pb2+ removal rate was at equilibrium on day 5 (≈86%) except for OP41447 and OP41448 (≈87%) on day 15. FTIR analysis reveals the involvement of functional groups O-H, C-H, N-H, O=C=O, C≡C, N=C=S, C=C, N-O, C-N, and S=O in the biosorption process. SEM showed distortion in the cellular structure of the fungi. These results indicated the lead remediation potential of the fungal strains.