Sorption of lead and copper from an aqueous phase system by marine-derived Aspergillus species

Abstract

A total of 47 cultures of Aspergillus representing 13 species were screened for their ability to tolerate 7.5 mM Pb2+ and 2 mM Cu2+, all of which were positive, with growth of 31 of the cultures being enhanced by low concentrations of lead. The isolates of Aspergillus versicolor, A. niger and A. flavus were tolerant to concentrations as high as 10-12.5 mM Pb2+ and 3-4 mM Cu2+. Selected cultures displayed a good sorption capacity of 32-41 mg Pb2+ and 3.5-6.5 mg Cu2+ g-1 dry weight of mycelia, which was improved by alkali pretreatment of the biomass and negatively affected by mild dry heat treatment. The sequestration of the metal occurred mainly by sorption to the cell-surface with very little intracellular uptake. FTIR analysis indicated the involvement of hydroxyl, amino, and carbonyl groups in Pb2+ and Cu2+ biosorption by fungal biomass of the different species of Aspergillus.