Heavy metal tolerance and adaptability assessment of indigenous filamentous fungi isolated from industrial wastewater and sludge samples

Abstract

A total of twenty-five isolates of fungi from the wastewater and sludge samples of a steel industry were screened for their resistance to Cu(II) and Ni(II). Three strains were finally selected and identified as Aspergillus awamori, Aspergillus flavus and Aspergillus niger. The growth behavior and concurrent bioaccumulation of Cu(II) and Ni(II) by each fungus was investigated as a function of pH of the growth medium and concentration of Cu(II) and Ni(II). pH for maximum growth with concurrent bioaccumulation of Cu(II) and Ni(II) was observed, respectively as 4.0 and 5.0 for A. awamori, 5.0 and 5.0 for A. flavus and 4.0 and 5.0 for A. niger. The growth behavior with increasing heavy metals concentration was also examined as tolerance index. Synergistic and inhibitory effect on growth with lower and higher concentration of both heavy metals, respectively observed for each fungus. Our finding indicates that the resistant strains isolated from their contaminated habitat have better pertinence and application in heavy metals bioremediation. Keywords: Aspergillus awamori, Aspergillus flavus, Aspergillus niger, Heavy metal, Tolerance index