Division of Environmental and Applied Biology, College of Life Sciences, University of Dundee, Dundee, DD1 4HN, Scotland, UK and Present address: P. O. Box 83034, Vista Centre, 1830 Bank Street, Ottawa, K1V 1A3, Ontario, Canada
The abilities of Aspergillus niger and Serpula himantioides to immobilize lead (Pb) from lead sulphide (PbS) were investigated. Upon growth on potato dextrose agar (PDA) amended with PbS which contained 10mM Pb, no visible solubilization activity was detected. A. niger produced biomass in greater quantity compared to S. himantiodes in both experimental and control media. With a ratio of 1.13, A. niger growth was stimulated on PbS-amended media while that of S. himantiodes, with a growth ratio of 0.46 was inhibited. Despite its smaller biomass, S. himantiodes accumulated over five times more Pb than A. niger with 85.7 Â± 4.9 Âµmol of Pb per g of dry weight while A. niger contained 14.6 Â± 1.3 Âµmol of Pb per g of its dry weight. Both fungi immobilized Pb through the formation of crystalline precipitates and energy dispersive x-ray analysis revealed the precipitates to be Pb containing. This transformation is of importance in the weathering of metal- bearing rocks as mineral neogenesis.