The geomicrobiology of gold

Reith, Frank, Lengke, Maggy F., Falconer, Donna, Craw, David and Southam, Gordon (2007) The geomicrobiology of gold. Isme Journal, 1 7: 567-584. doi:10.1038/ismej.2007.75


Author Reith, Frank
Lengke, Maggy F.
Falconer, Donna
Craw, David
Southam, Gordon
Title The geomicrobiology of gold
Journal name Isme Journal   Check publisher's open access policy
ISSN 1751-7362
1751-7370
Publication date 2007-11-01
Year available 2007
Sub-type Critical review of research, literature review, critical commentary
DOI 10.1038/ismej.2007.75
Open Access Status Not yet assessed
Volume 1
Issue 7
Start page 567
End page 584
Total pages 18
Place of publication London, United Kingdom
Publisher Nature Publishing Group
Language eng
Formatted abstract
Microorganisms capable of actively solubilizing and precipitating gold appear to play a larger role in the biogeochemical cycling of gold than previously believed. Recent research suggests that bacteria and archaea are involved in every step of the biogeochemical cycle of gold, from the formation of primary mineralization in hydrothermal and deep subsurface systems to its solubilization, dispersion and re-concentration as secondary gold under surface conditions. Enzymatically catalysed precipitation of gold has been observed in thermophilic and hyperthermophilic bacteria and archaea (for example, Thermotoga maritime, Pyrobaculum islandicum), and their activity led to the formation of gold- and silver-bearing sinters in New Zealand's hot spring systems. Sulphate-reducing bacteria (SRB), for example, Desulfovibrio sp., may be involved in the formation of gold-bearing sulphide minerals in deep subsurface environments; over geological timescales this may contribute to the formation of economic deposits. Iron- and sulphur-oxidizing bacteria (for example, Acidothiobacillus ferrooxidans, A. thiooxidans) are known to breakdown gold-hosting sulphide minerals in zones of primary mineralization, and release associated gold in the process. These and other bacteria (for example, actinobacteria) produce thiosulphate, which is known to oxidize gold and form stable, transportable complexes. Other microbial processes, for example, excretion of amino acids and cyanide, may control gold solubilization in auriferous top- and rhizosphere soils. A number of bacteria and archaea are capable of actively catalysing the precipitation of toxic gold(I/III) complexes. Reductive precipitation of these complexes may improve survival rates of bacterial populations that are capable of (1) detoxifying the immediate cell environment by detecting, excreting and reducing gold complexes, possibly using P-type ATPase efflux pumps as well as membrane vesicles (for example, Salmonella enterica, Cupriavidus (Ralstonia) metallidurans, Plectonema boryanum); (2) gaining metabolic energy by utilizing gold-complexing ligands (for example, thiosulphate by A. ferrooxidans) or (3) using gold as metal centre in enzymes (Micrococcus luteus). C. metallidurans containing biofilms were detected on gold grains from two Australian sites, indicating that gold bioaccumulation may lead to gold biomineralization by forming secondary 'bacterioform' gold. Formation of secondary octahedral gold crystals from gold(III) chloride solution, was promoted by a cyanobacterium (P. boryanum) via an amorphous gold(I) sulphide intermediate. 'Bacterioform' gold and secondary gold crystals are common in quartz pebble conglomerates (QPC), where they are often associated with bituminous organic matter possibly derived from cyanobacteria. This may suggest that cyanobacteria have played a role in the formation of the Witwatersrand QPC, the world's largest gold deposit.
Keyword Microorganisms
Gold
Geomicrobiology
Solubilization
Bioaccumulation
Biomineralization
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Critical review of research, literature review, critical commentary
Collection: School of Earth Sciences Publications
 
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