Biomineralization of Gold in Biofilms of Cupriavidus metallidurans

Lintern Fairbrother, B Etschmann, Joel Brugger, Joseph Shapter, G Southam, Frank Reith

    Research output: Contribution to journalArticlepeer-review

    45 Citations (Scopus)

    Abstract

    Cupriavidus metallidurans, a bacterium capable of reductively precipitating toxic, aqueous gold(I/III)-complexes, dominates biofilm communities on gold (Au) grains from Australia. To examine the importance of C. metallidurans biofilms in secondary Au formation, we assessed the biomineralization potential of biofilms growing in quartz-sand-packed columns to periodic amendment with Au(I)-thiosulfate. In these experiments, >99 wt % of Au, was retained compared to <30 wt % in sterilized and abiotic controls. Biomineralization of Au occurred in the presence of viable biofilms via the formation of intra- and extra-cellular spherical nanoparticles, which aggregated into spheroidal and framboidal microparticles of up to 2 μm in diameter. Aggregates of Au formed around cells, eventually encapsulating and ultimately replacing them. These particles were morphologically analogous to Au-particles commonly observed on natural Au grains. Bacterial cells were connected via exopolymer or nanowires to μm-sized, extracellular Au-aggregates, which would intuitively improve the flow of electrons through the biofilm. This study demonstrates the importance of C. metallidurans biofilms for the detoxification of Au-complexes and demonstrates a central role for bacterial biomineralization in the formation of highly pure Au in surface environments.

    Original languageEnglish
    Pages (from-to)2628-2635
    Number of pages8
    JournalEnvironmental Science and Technology
    Volume47
    Issue number6
    DOIs
    Publication statusPublished - 19 Mar 2013

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