ABSTRACT
Lead pollution and its associated aftereffects have existed as a major issue affecting the total quality of the environment. Traditional methods of remediating lead-contaminated sites include a variety of physical, thermal, and chemical treatments, which in general are expensive ex situ approaches. In this context, the efficiency of lead-resistant microorganisms for the bioremediation of lead-contaminated soils has emerged as a promising cost-effective technology for practical utilization. In general, the mechanisms of metal resistance in microbes include precipitation of metals such as phosphates, carbonates, and/or sulfides, volatilization via methylation or ethylation, physical exclusion of electro-negative components in the membranes and extracellular polymeric substances, energy-dependent metal efflux systems, and intracellular sequestration with low-molecular-weight, cysteine-rich proteins. Such mechanisms have been employed in the macrofungus Galerina vittiformis and the marine fungus Aspergillus terreus for the effective Pb uptake from soil and for the biosynthesis of PbSe quantum dots, respectively. The metal removal kinetic data for Pb(II) follow pseudo-second-order equation indicating the removal mechanism is a function of both metal ions and nature of microorganism.
