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 ± 4.9 μmol of Pb per g of dry weight
while
A. niger contained 14.6 ± 1.3 μmol 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 metalbearing
rocks as mineral neogenesis.
