Using iron and sulphur oxidising bacteria to catalyse the breakdown of sulphides that host the gold is an important biological method for the pretreatment of refractory gold ores. Following this biological treatment, a combination of chemical and physical methods is used for leaching (such as the cyanide process) and concentration (such as carbon in pulp or electrowinning) of the gold. Although these methods are well accepted by industry, they harbour limitations in the processing of low grade refractory ores and regulatory agency/public acceptance of cyanide use. Thus, it is beneficial for industry to develop environmentally friendly, as well as cost efficient, leaching and concentration techniques that are based on micro-organisms. This may soon be possible by adapting the results of recent multidisciplinary research, which has shown that micro-organisms are capable of driving a biogeochemical cycle of gold dispersion, transport and re-concentration in the supergene environment. The indigenous microbiota in biologically active soil microcosms from a number of Australian sites are capable of solubilising up to 80 wt-% of the gold contained in soils and deeper regolith materials. Studies using molecular microbial techniques have shown that a metallophilic bacterium, Cupriavidus metallidurans, is present in biofilms on gold grains from a number of Australian sites. Cupriavidus metallidurans is capable of actively accumulating gold from solution and therefore contributes to the formation of secondary gold grains and nuggets. Identifying the biochemical and physiological pathways that lead to the dispersion and accumulation of gold in regolith and quantifying the reaction kinetics of these processes may thus lead to the development of industrial bio-processing capacities for gold containing ores.
AdamsJB, PalmerF, StaleyJT. 1992. Rock weathering in deserts: Mobilisation and concentration of ferric iron by micro-organisms, Geomicrobiol. J., 10, 99–114.
2.
AylmoreMG, MuirDM. 2001a. Thiosulfate leaching of gold – a review, Miner. Eng., 14, 135–174.
3.
AylmoreMG, MuirDM. 2001b. Thermodynamic analysis of gold leaching by ammoniacal thiosulfate using Eh/pH and speciation diagrams. SME Preprint 01-142.
4.
BakerBJ, LutzMA, DawsonSC, BondPL, BanfieldJF. 2004. Metabolically active eukaryotic communities in extremely acidic mine drainage, Appl. Environ. Microbiol., 70, 6264–6271.
5.
BanfieldJF, HamersRJ. 1997. Processes at minerals surfaces with relevance to micro-organisms and prebiotic systems, in Geomicrobiology: interactions between microbes and minerals, Reviews in Mineralogy 35, (ed. , BanfieldJ F, NealsonK H, ed), 81–117, Washington DC, Mineralogical Society of America.
6.
BeveridgeTJ, MurrayRGE. 1976. Uptake and retention of metals by cell walls of Bacillus subtilis, J. Bacteriol., 127, 1502–1518.
7.
BoseckerK. 1997. Bioleaching: metal solubilization by micro-organisms, FEMS Microbiol. Rev., 20, 591–604.
8.
BruggerJ, PringA, RyanC, ReithF, EtschmannB, LiuW, O'NeillB, NgothaiY. 2010. Probing ore deposits formation: new insights and challenges from synchrotron and neutron studies, Radiat. Phys. Chem., 79, 151–161.
9.
CastanierS, le Me'tayer-LevrelG, PerthuisotJP. 1999. Bacterial roles in the precipitation of carbonate minerals, in Microbial sediments, (ed. , RidingR, AwramikS, ed), 331, Berlin, Springer.
10.
EhrlichHL. 1996. How microbes influence mineral growth and dissolution, Chem. Geol., 132, 1–3.
11.
EhrlichHL. 1998. Geomicrobiology: its significance for geology, Earth Sci. Rev., 45, 45–60.
FairbrotherL, ShapterJ, PringA, SouthamG, BruggerJ, ReithF. 2009. Effect of the cyanide-producing bacterium Chromobacterium violaceum on ultraflat gold surfaces, Chem. Geol., 265, 313–320.
14.
FalconerD, CrawD. 2009. Supergene gold mobility: a textural and geochemical study from gold placers in southern New Zealand, Econ. Geol. Sp. Pub., 14, 77–93.
15.
FaramarziMA, BrandlH. 2006. Formation of water soluble metal cyanide complexes from solid minerals by Pseudomonas plecoglossicida, FEMS Microbiol. Lett., 259, 47–52.
16.
FaramarziMA, StagarsM, PensiniE, KrebsW, BrandlH. 2004. Metal solubilization from metal-containing solid materials by cyanogenic Chromobacterium violaceum, J. Biotechnol., 113, 321–326.
17.
FitzRM, CypionkaH. 1990. Formation of thiosulfate and trithionate during sulfite reduction by washed cells of Desulfovibrio desulfuricans, Arch. Microbiol., 154, 400–406.
18.
FyfeWS. 1996. The biosphere is going deep, Science, 273, 448.
19.
GeeAR, DudeneyAWL1988. Adsorption and crystallisation of gold at biological surfaces, in BioHydrometallurgy: Proceedings Internat. Symp., , NorrisP R, KellyD P, ed, (eds.), Sci Technol Letters, Kew, Surrey, U.K., 437–451.
20.
HanTM, RunnegarB. 1992. Megascopic sukaryotic algae from the 2·1 billion year old Negaunee Iron formation, Michigan, Science, 257, 232–235.
21.
HoughRM, ButtCRM, ReddySM, VerrallM. 2007. Gold nuggets: supergene or hypogene?Aust. J. Earth Sci., 54, 959–964.
JuniperSK, TeboBM. 1995. Microbe-metal interactions and mineral deposition at hydrothermal vents, in The microbiology of deep sea hydrothermal vents, (ed. , KarlD M, ed), 219–253, Boca Raton, FL, CRC Press.
24.
KaramushkaVI, GruzinaTG, PodolskaVI, UlbergZR. 1987a. Interaction of glycoprotein of Bacillus pumilis cell wall with liposomes, Ukr. Biokhim. Zh., 59, 70–75.
25.
KaramushkaVI, GruzinaTG, UlbergZ.R. 1990a. Effect of respiratory toxins on bacterial concentration of trivalent gold, Ukr. Biokhim. Zh., 62, 103–105.
26.
KaramushkaVI, UlbergZR, GruzinaTG, PodolskaVI, PertsovNV. 1987b. Study of the role of surface structural components of micro-organisms in heterocoagulation with colloidal gold particles, Pricl. Biokhim. Microbiol., 23, 697–702.
27.
KaramushkaVI, UlbergZR, GruzinaTG. 1990b. The role of membrane processes in bacterial accumulation of Au(III) and Au(0), Ukr. Biokhim. Zh., 62, 76–82.
28.
KarthikeyanS, BeveridgeTJ. 2002. Pseudomonas aeruginosa react with and precipitate toxic soluble gold, Environ. Microbiol., 4, (11), 667–675.
29.
KashefiK, TorJM, NevinKP, LovleyD. 2001. Reductive precipitation of gold by dissimilatory Fe(III)-reducing bacteria and archaea, Appl. Environ. Microbiol., 67, 3275–3279.
30.
KeimCN, FarinaM. 2005. Gold and silver trapping by uncultured magnetotactic cocci, Geomicrobiol. J., 22, 55–63.
31.
KemnerK, KellySD, LaiB, MaseJ, O'LoughlinEJ, Sholto-DouglasD, CaiZ, SchneegurtMA, KulpaCF, NealsonKH. 2004. Elemental and redox analysis of single bacterial cells by X-ray microbeam analysis, Science, 306, 686–687.
32.
KrebsW, BrombacherC, BosshardPP, BachofenR, BrandlH. 1997. Microbial recovery of metals from solids.FEMS Microbiol. Rev., 20, 605–617.
33.
KunertJ, StranskyZ. 1988. Thiosulfate production from cystine by the kerarinolytic prokaryote Streptomyces fradiae, Arch. Micriobiol., 150, 600–601.
34.
LedinM, PedersenK. 1996. The environmental impact of mine wastes – roles of micro-organisms and their significance in treatment of mine wastes, Earth Sci. Rev., 41, 67–108.
35.
LengkeMF, FleetME, SouthamG. 2006a. Morphology of gold nanoparticles synthesized by filamentous cyanobacteria from gold(I) thiosulfate and gold(III) chloride complexes, Langmuir, 22, 2780–2787.
36.
LengkeMF, FleetME, SouthamG. 2006b. Bioaccumulation of gold by filamentous cyanobacteria between 25 and 200°C, Geomicrobiol. J., 23, 591–597.
37.
LengkeMF, RavelB, FleetME, WangerG, GordonRA, SouthamG. 2006 c. Mechanisms of gold bioaccumulation by filamentous cyanobacteria from gold(III) chloride complex, Environ. Sci. Technol., 40, 6304–6309.
38.
LengkeMF, SouthamG. 2005. The effect of thiosulfate-oxidizing bacteria on the stability of the gold-thiosulfate complex, Geochim. Cosmochim. Acta, 69, 3759–3772.
39.
LengkeMF, SouthamG. 2006. Bioaccumulation of gold by sulphate-reducing bacteria cultured in the presence of gold(I) thiosulfate complex, Geochim. Cosmochim Acta, 70, 3646–3661.
40.
LittleBJ, WagnerPA, LewandrowskiZ. 1997. Spatial relationships between bacteria and mineral surfaces, in Geomicrobiology: interactions between microbes and minerals, Reviews in Mineralogy 35, (ed. , BanfieldJ F, NealsonK H, ed), 123–155, Washington, DC, Mineralogical Society of America.
LovleyDR, PhillipsEJP., 1988. Novel mode of microbial energy metabolism: organic carbon oxidation coupled to dissimilarory reduction of iron and manganese.Appl. Environ. Microbiol.54, 1472–1480.
43.
MadiganMT, MartinkoJM. 2006. Brock – biology of micro-organisms, 11th edn, New York, Pearson, Prentice Hall.
44.
McPhailDC, UsherA, ReithF. 2006. On the mobility of gold in the regolith: results and implications from experimental studies, Proc. CRC LEME Regolith Symp., (ed. , FitzpatrickR W, ShandP, ed), 386, Bentley, WA, Cooperative Research Centre for Landscape Environments and Mineral Exploration.
45.
MergeayM, MonchyS, VallaeysT, AuquierV, BenotmaneA, BertinP, TaghaviS, DunnJ, van der LelieD, WattiezR. 2003. Ralstonia metallidurans, a bacterium specifically adapted to toxic metals: towards a catalogue of metal responsive genes, FEMS Microbiol. Rev., 27, 385–410.
46.
MossmanDJ, ReimerT, DurstlingH. 1999. Microbial processes in gold migration and deposition: modern analogues to ancient deposits, Geosci. Can., 26, 131–140.
47.
NakajimaA. 2003. Accumulation of gold by micro-organisms, W. J. Microbiol. Biotechnol., 19, 369–374.
48.
NealsonKH, StahlDA. 1997. Micro-organisms and biogeochemical cycles: what can we learn from layered microbial communities?Rev. Mineral., 35, 5–34.
49.
NiesDH. 2000. Heavy metal resistant bacteria as extremophiles: molecular physiology and biotechnological use of Ralstonia sp. Ch.34, Extremophiles, 4, 77–82.
50.
NordstromDK, SouthamG. 1997. Geomicrobiology of sulfide metal oxidation, Rev. Mineral., 35, 361–390.
51.
OlsonGJ, BrierleyJA, BrierleyCL. 2003. Bioleaching review part B: progress in bioleaching: applications of microbial processes by the minerals industries, Appl. Microbiol. Biotechnol., 63, 249–257.
52.
ParkesRJ, CragBA, BaleSJ, GetliffJM, GoodmanK, RochellePA, FryJC, WeightmanAJ, HarveySM. 1994. Deep bacterial biosphere in Pacific Ocean sediments, Nature, 371, 410–413.
53.
PedersenK, 1993. The deep subterranean biosphere.Earth Sci. Rev, 34, 243–260.
54.
QuinteroEJ, LangilleSE, WeinerRM. 2001. The polar polysaccharide capsule of hyphomonas adhaerens MHS-3 has a strong affinity for gold, J. Indust. Microbiol. Biotechnol., 27, 1–4.
55.
RawlingsDE. 2002. Heavy metal mining using microbes, Ann. Rev. Microbiol., 56, 65–91.
56.
ReithF, BruggerJ, ZammitCM, GreggAL, GoldfarbKC, AndersenGL, DeSantisTZ, PicenoYM, BrodieEL, LuZ, HeZ, ZhouJ, WakelinSA. 2012a. Influence of geogenic factors on microbial communities in metallogenic Australian soils, ISME J., doi:10·1038/ismej.2012·48
57.
ReithF, EtschmannB, DartRC, BreweDL, VogtS, Schmidt MummA, BruggerJ2011. Distribution and speciation of gold in biogenic and abiogenic calcium carbonates – Implications for the formation of gold anomalous calcrete. Geochimica et Cosmochimica Acta, 75, 1942–1956.
58.
ReithF, EtschmannB, GrosseC, MoorsH, BenotmaneMA, MonsieursP, GrassG, DoonanC, VogtS, LaiB, Martinez-CriadoG, GeorgeGN, NiesD, MergeayM, PringA, SouthamG, BruggerJ. 2009a. Mechanisms of gold biomineralization in the bacterium Cupriavidus metallidurans, PNAS, 106, 17757–17762.
59.
ReithF, FairbrotherL, NolzeG, WilhelmiO, ClodePL, GreggA, ParsonsJE, WakelinSA, PringA, HoughR, SouthamG, BruggerJ. 2010. Nanoparticle factories: biofilms hold the key to gold dispersion and nugget formation, Geology, 38, 843–846.
60.
ReithF, LengkeMF, FalconerD, CrawD, SouthamG. 2007. Winogradski review – the geomicrobiology of gold, ISME J., 1, 567–584.
61.
ReithF, McPhailDC. 2006. Effect of resident microbiota on the solubilization of gold in soils from the Tomakin Park Gold Mine, New South Wales, Australia, Geochim. Cosmochim. Acta, 70, 1421–1438.
62.
ReithF, McPhailDC. 2007. Microbial influences on solubilisation and mobility of gold and arsenic in regolith samples from two gold mines in semi-arid and tropical Australia, Geochim. Cosmochim. Acta, 71, 1183–1196.
63.
ReithF, McPhailDC, ChristyAG. 2005. Bacillus cereus, gold and associated elements in soil and regolith samples from Tomakin Park Gold Mine in south-eastern New South Wales, J. Geochem. Explor., 85, 81–89.
64.
ReithF, RogersSL. 2008. Assessment of bacterial communities in auriferous and non-auriferous soils using genetic and functional fingerprinting, Geomicrobiol. J., 25, 203–215.
65.
ReithF, RogersSL, McPhailDC, WebbD. 2006. Bio-mineralization of gold: biofilms on bacterioform gold.Science, 313, 333–336.
66.
ReithF, StewartL, WakelinSA. 2012b. Supergene gold transformation: secondary and nano-particulate gold from southern New Zealand, Chem. Geol., 320, 32–45.
67.
ReithF, WakelinS, Schmidt MummA. 2009b. A microbial pathway for the genesis of gold anomalous regolith carbonates, Chem. Geol., 258, 315–326.
68.
SandW, GehrkeT, JozsaPG, SchippersA. 2001. Biochemistry of bacterial leaching – direct vs. indirect bioleaching.Hydrometallurgy, 59, 159–175.
Schmidt MummA, ReithF. 2007. Biomediation of calcrete at the gold anomaly of the Barns prospect, Gawler Craton, South Australia, J. Geochem. Explor., 92, 13–33.
71.
SouthamG, BeveridgeTJ. 1996. The occurrence of sulfur and phosphorus within bacterially derived crystalline and pseudo-crystalline gold formed in vitro, Geochim Cosmochim. Acta, 60, 4369–4376.
72.
SouthamG, LengkeMF, FairbrotherL, ReithF. 2009. The biogeochemistry of gold, Elements, 5, 303–307.
73.
SouthamG, SaundersJA. 2005. The geomicrobiology of ore deposits, Econ. Geol., 100, 1067–1084.
74.
UlbergZR, KaramushkaVI, VidybidaAK. 1992. Interaction of energized bacteria calls with particles of colloidal gold: peculiarities and kinetic model of the process, Biochim. Biophys. Acta, 1134, 89–95.
75.
UsherA, McPhailDC, BruggerJ. 2009. A spectrophotometric study of aqueous Au(III) halide-hydroxide complexes at 25-80°C.Geochimica et Cosmochimica Acta, 73, 3359–3380.
76.
VincentWF, JamesMR. 1996. Biodiversity in extreme aquatic environments – lakes, ponds and streams of Ross Sea sector, Antarctica, Biodivers. Conserv., 5, 1451–1471.
77.
von RozyckiT, NiesDH, SaierMH. 2005. Genomic analyses of transport proteins in Ralstonia metallidurans, Comp. Funct. Genom., 6, 17–56.
78.
WanR, LeVierKM. 2003. Solution chemistry factors for gold thiosulfate heap leaching, Int. J. Miner. Process., 72, 311–322.
79.
WidadaJ, NorjiriY, OmoriT. 2002. Recent developments in molecular techniques for identification and monitoring of xenobiotic-degrading bacteria and their catabolic genes in bioremediation, Appl. Microbiol. Biotechnol., 60, 45–59.
80.
WitkiewiczPL, ShawCF. 1981. Oxidative cleavage of peptide and protein disulphide bonds by gold(III): a mechanism for gold toxicity, J. Chem. Soc. Chem. Commun., 21, 1111–1114.
81.
WoolfolkCA, WhiteleyHR. 1962. Reduction of inorganic compounds with molecular hydrogen by Micrococcus lactylyticus: stoichiometry with compounds of arsenic, selenium, tellurium, transition & other elements, J. Bacteriol., 84, 647–658.
82.
ZhouJ. 2003. Microarrays for bacterial detection and microbial community analysis, Curr. Opin. Microbiol., 6, 288–294.
