Monday, September 20, 2010

Microbes move gold with groundwater flow

Bacteria make gold nuggets
Discovery News: Gold nuggets are often the creations of bacterial biofims, say Australian researchers who have demonstrated the process and even identified the bacteria at work.

Layers of bacteria can actually dissolve gold into nanoparticles, which move through rocks and soils, and then deposit it in other places, sometimes creating purer 'secondary' gold deposits in cracks and crevices of rocks. The process overturns the long-held belief by some scientists that gold ore is created only by 'primary' physical geological processes...

The University of Adelaide's Frank Reith and his colleagues discovered that 90 percent of the bacteria were of just two species, Delftia acidovorans and Cupriavidus metallidurans. The bacteria share genes that make them resistant to the toxic effects of heavy metals... The discovery appears in the September issue of the journal Geology.

'We tagged the DNA and saw the beautiful active biofilm (dissolving the gold), said [Joel] Brugger. 'That was very interesting because gold in soluble form is very toxic.' That dissolved gold can then be redeposited in other places in a much purer form... 'At the moment we don't really understand how gold moves around in the environment,' said Brugger. 'I think that here we can see for the first time how it happens.' Microbes move it around with the groundwater flow.
Image source here.