Isolation and identification of cadmium-tolerant filamentous fungi from lead-zinc tailings

Abstract:

[Objective] The aim of this study is to isolate efficient cadmium-tolerant fungi from soils contaminated by heavy metals, and thereby to provide strains for heavy metals’ bioremediation. [Methods] Nine soil samples from Bingcun Pb-Zn mining waste land, Mei County, Guangdong Province, were used to isolate by dilution plate coating method with four different media. Strains were identi?ed by morphology and ITS rDNA sequence analyses. Minimum inhibitory concentration (MIC) for the isolated strains was also determined. [Results] Seventy-two cadmium-tolerant filamentous fungi belonging to the genera Aspergillus, Penicillium, Cladosporium, Lecythophora, Paecilomyces, Fusarium and others were isolated from the mining land. Four strains, i.e. Paecilomyces lilacinus (Thom) Samson (6-20p), Penicillium pinophilum Hedgcock (6-16p), Penicillium rolfsii Thom (6-16m) and Fusarium oxysporum Schlecht. (8-11p), were resistant to high cadmium concentrations of 200, 40, 25, and 15 mmol/L, respectively. [Conclusion] The strains isolated from contaminated soils showed minimum cadmium-tolerance to 1 mmol/L, thus they may play a role in the bioremediation of heavy metal pollution soils. The results imply the promising biosorption of cadmium-tolerant strains for bioremediation of heavy metals.