Understanding microbial communities associated with mineral-rich systems may help to reveal new exploration targets.

The challenge

Characterising microbial communities surrounding ore types

Little is known about the make-up and behaviour of microbial communities within or near ore deposits.

Subtle changes in the environment, such as varying metal concentrations, nutrient availability and the presence of natural aquifers, will affect microbial communities near and within mineral-rich areas.

Understanding microbial communities, linked to mineral rich systems, could provide another approach in the repertoire of mineral exploration tools.

Our response

Linking microbes to minerals

We've used our multi-disciplinary expertise in geology and microbiology to begin characterising the microbial species associated with different types of ore deposits.

Analysing core and regolith samples, we have collected data on the bacterial, archaeal (single-celled organisms) and fungal diversity along with associated geology and minerology, in order to build 3D microbiome models.

These 3D models give detailed information about the microbial communities associating with specific minerology which exist deep underground.

Cataloguing and characterising the microbiome at the surface and in deep terrestrial and regolith samples is helping us understand the distinct difference between microbial communities between different types of ore.

This knowledge is helping us build a picture of how microbiomes deep below the surface may create surface features which may suggest the presence of specific ores. By interpreting these proxy markers, new exploration targets may be revealed.

The results

Gold-coated fungi

[Animation images appear of different types of gold including a sarcophagus, a sphynx, a stack of coins, a gold bar, a champagne flute, jewellery, a calculator, a Smartphone and a laptop]

Narrator: Gold has fascinated the world since ancient times, treasured primarily as a trusted source of wealth, for use in jewellery, to many modern electronics.

[Animation image changes to show gold dots rotating on the screen and then the gold dots gradually morph into a globe of the world with gold dots showing on the various countries]

Today, we’re still learning about our favourite yellow metal, such as how a gold deposit is formed and how it travels around the earth, so that we can come up with much-needed and clever new strategies to find and produce it.

[Camera zooms out a little on the world globe and a magnifying glass appears moving around the rotating world globe]

Geologists from Australia’s national science agency, CSIRO, are revealing some of gold’s secrets and coming up with innovative ways to search for gold faster, in a more cost-effective way and in ways that reduce impacts to the environment.

[Animation image changes to show a tree in a landscape]

For example, researchers have been looking for nature’s clues at the surface that could be used as evidence to find gold metres below.

[Animation image shows streaks of gold moving up the tree trunk and then a magnifying glass symbol appears over the foliage of the tree showing small gold dots inside the leaves]

CSIRO discovered that trees in the Kalgoorlie region of Western Australia can draw up gold from the earth and deposit it in their leaves

[Animation image moves to the left and streaks of gold appear moving up a termite mound in a group of termite mounds in the landscape on the right]

and that termites can harbour gold in their mounds.

[Animation image continues to move to the left and streaks of gold moving up a pink fungi in a group of fungi appear on the right]

Now in the latest breakthrough, scientists have discovered gold-coated fungi.

[Camera zooms in on the fungi to show gold dots over the surface]

This thread-like fungi lives in soils and zooming in on this organism reveals balls of gold attached to its strands. The gold gets there through an oxidisation process. A surprising discovery given gold is so chemically inactive. The fungi dissolves and precipitates particles of gold from their surroundings and then attaches it to their strands.

[Camera zooms out to show the gold streaks moving up the pink fungi in a group of fungi and then the image shows the pink fungi growing taller than the other fungi and then more pink fungi popping up]

And interestingly, there appears to be a biological advantage in doing so as the gold-coated fungi have been found to grow larger and spread faster than those that don’t interact with gold.

[Camera gradually zooms out and more coloured fungi appear growing around the pink fungi]

They also play a central role in a biodiverse soil community, meaning the gold-coated fungi play host to a more diverse range of other fungi when compared to those that don’t.

[Animation image changes to show a rotating world globe showing gold dots over the various continents]

This is the first evidence that fungi may play a role in the cycling of gold around the earth’s surface.

[Animation image changes to show layers of soil containing gold dots beneath a blue fungi which is drawing streaks of gold up into the stem from the layers of soil]

Research continues to understand whether or not the gold-coated fungi could be linked to a gold deposit below the surface.

[Image changes to show the CSIRO logo on a dark blue screen]

At CSIRO, we’re solving the greatest challenges through science and innovation. Our mineral exploration research, is leading to new tools for more sustainable exploration and production of gold for future generations.

Gold-coated fungi discovered in Western Australia

We discovered a gold coated fungi in samples taken near Boddington, Western Australia.

The fungi, Fusarium oxsporum, is commonly found in soils around the world and produces a pink mycelium or "flower".

We found that the thread-like fungi attach gold to their strands by dissolving and precipitating particles from their surroundings.

The gold may also offer a biological advantage, as the gold-coated fungi were found to grow larger and spread faster than those that don't interact with gold and play a central role in a biodiverse soil community.

The discovery of this fungi interacting with gold provides a curious example of how microbial sampling could provide another tool for mineral exploration.

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