The role of bacteria in platinum formation

The University of Adelaide has led research into the role of specialist bacteria in the formation and movement of platinum and related metals in surface environments. The study, published in the journal Nature Geoscience, has important implications for the future exploration of platinum group metals.

Platinum group metals, especially platinum and palladium, are highly prized ‘noble’ metals used in a wide range of industrial processes. Ensuring adequate supplies is challenging and enhanced exploration is considered a global priority.

“These platinum group elements are strategically important metals, but finding new deposits is becoming increasingly difficult due to our limited understanding of the processes that affect the way they are cycled through surface environments,” said project leader Dr Frank Reith, senior lecturer in the university’s School of Biological Sciences and visiting researcher at CSIRO Land and Water.

“Traditionally it was thought that these platinum group metals only formed under high pressure and temperature systems deep underground, and that when they were brought to the surface through weathering and uplift, they just sat there and nothing further happened to them.

“We’ve shown that that is far from the case.”

Investigating platinum group elements from Brazil, Colombia and Tasmania, the researchers found live bacterial biofilms on mineral grains from all three sites using scanning electron microscopy, with the dispersion and reconcentration of these elements in surface environments. These biofilms had been suggested previously but never before shown to exist.

“We’ve shown that nuggets of platinum and related metals can be reformed at the surface through bacterial processes,” said Dr Reith.

“And we’ve shown that, at the Brazil site at least, the entire process of formation of platinum and palladium was mediated by microbes.”

The research therefore reveals the key role of bacteria in the secondary formation of platinum grains. According to Dr Reith, the search for specific microorganisms associated with platinum group metals could lead exploration companies directly to new deposits under the surface.

“It is very similar to when police look for a suspect,” he said. “They find a cigarette butt somewhere and extract the DNA and then they get a fingerprint and they can match it to the suspect. In very simple terms, we can do the same with microbial communities in soil sediments.”

Image caption: Panning for platinum grains in Brazil — Frank Reith, University of Adelaide, and Barbara Etschmann, Monash University. Image credit: University of Adelaide.

Originally published here.