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:
Medline for lead metabolism AND bacteria
Thayer JS. Biological methylation of less-studied elements. Appl Organometal Chem. 2002;16:677-91.