STIMULATION OF BIOLOGICAL UPTAKE OF HEAVY-METALS

This research was conducted to investigate the relative capabilities of unacclimated, acclimated, and cysteine-cystine-stimulated aerobic cultures to remove heavy metals. Loss of organism viability was observed at metal concentrations above 30 mg/L, however, loss of cell viability did not affect metal uptake. Metal-complexing capacities from 0.041 to 2.13 mg/mg protein were observed. Metal removal from binary and ternary mixtures exceeded those of single metals. Surprisingly, culture acclimation resulted in reduced metal uptake. However, a cysteine-cystine-stimulated culture had substantially increased metal-removal capabilities possibly due to the synthesis of metallothionein-like proteins. Biopolymers of the unacclimated organisms had an affinity for metal binding of the order: Cu > Pb > Cd. This research points to the feasibility of in-vitro detoxification of high metal-content hazardous wastes by cell materials derived from cysteine-cystine-stimulated chemostat cultures. Coupling in-vitro metal complexation with metal leaching from biosolids could provide an opportunity for recycling hazardous heavy metals.