Biomineralization of Galena by Sulfate Reducing Bacteria

In most near-surface environments lead (Pb) has low solubility in the aqueous phase, yet through complexation and pH/redox variation Pb(II) can be mobilized. In these situations biomineralization and sorption has been a focus of potential remediation and/or attenuation techniques. However, further study is needed to comprehend the various mechanisms by which microbes can influence Pb mobility. Here, we used Desulfovibrio desulfuricans, a common sulfate reducing bacteria, to produce biogenic lead sulfide (PbS) and investigate the differences between biogenic and abiotically formed PbS. The biogenically formed PbS precipitate/biomass was analyzed at various reaction times with electron microscopy and X-ray adsorption techniques. D. desulfuricans precipitated nanoscale, monodisperse crystalline PbS (galena) after 72 hours of contact. We use acid volatile sulfide extractions to further evaluate the stability of the biogenically formed PbS and compare its resistance to dissolution to similar solids precipitated in the absence of microbes. The biogenic precipitate/biomass released less Pb than abiotic amorphous precipitates. This has application in remediation systems, and manufacture of nanoscale PbS, and providing insight into the microbial influence on global cycling of Pb.