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

Reith, Frank, Fairbrother, Lintern, Nolze, Gert, Wilhelmi, Oliver, Clode, Peta L., Gregg, Adrienne, Parsons, John E., Wakelin, Steven A., Pring, Allan, Hough, Robert, Southam, Gordon and Brugger, Joel (2010) Nanoparticle factories: Biofilms hold the key to gold dispersion and nugget formation. Geology, 38 9: 843-846. doi:10.1130/G31052.1

Author Reith, Frank
Fairbrother, Lintern
Nolze, Gert
Wilhelmi, Oliver
Clode, Peta L.
Gregg, Adrienne
Parsons, John E.
Wakelin, Steven A.
Pring, Allan
Hough, Robert
Southam, Gordon
Brugger, Joel
Title Nanoparticle factories: Biofilms hold the key to gold dispersion and nugget formation
Journal name Geology   Check publisher's open access policy
ISSN 0091-7613
Publication date 2010-09
Year available 2010
Sub-type Article (original research)
DOI 10.1130/G31052.1
Open Access Status
Volume 38
Issue 9
Start page 843
End page 846
Total pages 4
Place of publication Boulder, CO United States
Publisher Geological Society of America
Collection year 2010
Language eng
Formatted 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.
Keyword Placer gold
Filamentous Cyanobacteria
Cupriavidus Metallidurans
Budding Bacteria
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Earth Sciences Publications
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