Nanoparticle factories: Biofilms hold the key to gold dispersion and nugget formation

Frank Reith, Lintern Fairbrother, Gert Nolze, Oliver Wilhelmi, Peta Clode, Adrienne Gregg, John Parsons, Steven Wakelin, Allan Pring, Robert Hough, Gordon Southam, Joel Brugger

    Research output: Contribution to journalArticle

    103 Citations (Scopus)

    Abstract

    Biofilms living on gold (Au) grains play a key role in the biogeochemical cycle of Au by promoting the dispersion of Au via the formation of Au nanoparticles as well as the formation of secondary biomorphic Au. Gold grains from Queensland, Australia, are covered by a polymorphic, organic-inorganic layer that is up to 40 μm thick. It consists of a bacterial biofilm containing Au nanoparticles associated with extracellular polymeric substances as well as bacterioform Au. Focused ion beam (FIB) sectioning through the biofilm revealed that aggregates of nanoparticulate Au line open spaces beneath the active biofilm layer. These aggregates (bacterioform Au type 1) resulted from the reprecipitation of dissolved Au, and their internal growth structures provide direct evidence for coarsening of the Au grains. At the contact between the polymorphic layer and the primary Au, bacterioform Au type 2 is present. It consists of solid rounded forms into which crystal boundaries of underlying primary Au extend, and is the result of dealloying and Ag dissolution from the primary Au. This study demonstrates that (1) microbially driven dissolution, precipitation, and aggregation lead to the formation of bacterioform Au and contribute to the growth of Au grains under supergene conditions, and (2) the microbially driven mobilization of coarse Au into nanoparticles plays a key role in mediating the mobility of Au in surface environments, because the release of nanoparticulate Au upon biofilm disintegration greatly enhances environmental mobility compared to Au complexes only.

    Original languageEnglish
    Pages (from-to)843-846
    Number of pages4
    JournalGeology
    Volume38
    Issue number9
    DOIs
    Publication statusPublished - 2010

    Fingerprint Dive into the research topics of 'Nanoparticle factories: Biofilms hold the key to gold dispersion and nugget formation'. Together they form a unique fingerprint.

  • Cite this

    Reith, F., Fairbrother, L., Nolze, G., Wilhelmi, O., Clode, P., Gregg, A., Parsons, J., Wakelin, S., Pring, A., Hough, R., Southam, G., & Brugger, J. (2010). Nanoparticle factories: Biofilms hold the key to gold dispersion and nugget formation. Geology, 38(9), 843-846. https://doi.org/10.1130/G31052.1