Mycoremediation of heavy metal (Cd and Cr)-polluted soil through indigenous metallotolerant fungal isolates

Abstract

Remediation of heavy metals, other than microbial bioleaching method, is expensive and unsuitable for large contaminated areas. The current study was aimed to isolate, identify, and test the potential of indigenous fungal strains for heavy metal removal from contaminated soil. A total of three metallotolerant fungal strains, i.e., Aspergillus niger (M1DGR), Aspergillus fumigatus (M3Ai), and Penicillium rubens (M2Aii), were isolated and identified by phenotyping and genotyping from heavy metal-contaminated soil of Hattar Industrial Estate, Pakistan. A. niger was found to be the most successful strain for the removal of heavy metals from the contaminated soil with maximum bioaccumulation efficiency of 98% (Cd) and 43% (Cr). In contrast, A. fumigatus showed comparatively low but still considerable bioleaching potential, i.e., 79% and 69% for Cd and Cr removal, respectively. Maximum metal uptake efficiency, i.e., 0.580 mg g^-1 and 0.152 mg g^-1 by A. niger strain was noticed for Cd and Cr with Czapek yeast extract (CYE) and Sabouraud dextrose broth (SDB) media, respectively. A. fumigatus (M3Ai) exhibited the maximum bioleaching capacity (0.40 mg g^-1) for Cr with CYE medium. The results reveal that A. niger M1DGR and A. fumigatus M3Ai could be used to develop new strategies to remediate soil contaminated with heavy metals (Cd and Cr) through either in situ or ex situ mycoremediation.

Keywords: Hattar Industrial Estate (HIE); Heavy metal; Indigenous microbes; Mycoremediation.