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...