Lead is known to cause neurological damage in humans, with children being most susceptible to the toxic effects of lead (ToxFAQs: Lead). Some of the lead that is present in the environment is from its use in batteries, gasoline, hunting ammunition, and paint. No biological function for lead has been identified. Lead concentrations up to 300 ppm were found to stimulate growth in Escherichia coli, but higher lead concentrations inhibited growth (Kumar and Upreti, 2000).

Lead resistance in bacteria has been attributed to efflux of Pb2+ via P-type ATPases that are known to also transport Cd2+ and Zn2+ (Rensing et al, 1998). An operon encoding a P-type ATPase that is reported to be specific for Pb2+ efflux has been cloned from Ralstonia eutropha CH34 (Borremans et al, 2001). Lead resistance in Streptomyces subrutilis is proposed to occur by secretion of an extracellular protein that binds and precipitates lead (So et al, 2001).

Biosorption and bioaccumulation of soluble lead has been studied using living or dead biomass of bacteria (Leung et al, 2001), fungi (reviewed by Volesky, 1994), algae (Klimmek et al, 2001), and protozoa (Fernandez-Leborans and Herrero, 2000). Aspergillus niger was found to mobilize lead from the mineral pyromorphite (Pb5(PO4)3Cl) through secretion of acidic metabolites, and to subsequently redeposit the mobilized lead as insoluble lead oxalate (Sayer et al, 1999). Burkholderia cepacia biofilms grown in a defined medium were found to precipitate soluble lead as a pyromorphite (Pb5(PO4)3(OH)) (Templeton et al, 2003). Methylated lead derivatives have been detected in the environment, some of which may originate from biological activity. However, biomethylation of lead has not been conclusively proven (reviewed by Thayer, 2002).

For more information:

Search Medline for lead metabolism AND bacteria

Thayer JS. Biological methylation of less-studied elements. Appl Organometal Chem. 2002;16:677-91.


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