From the upcoming September/October Gold Prospectors Magazine (2019)
On the hunt for gold?
You can put away the pan and pickaxe and look for one of Earth’s simplest life forms giving itself the royal treatment.
Start near Boddington in western Australia, where a team of researchers from the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and local universities have discovered that an ordinary soil fungus is a literal gold digger, potentially acting as a treasure map.
Fusarium oxysporum, a microbe with fuzzy pink flowers, reaches its slender tendrils into the earth in order to grow and spread, just like any other fungus, except this one interacts with underground chemicals to attract miniscule gold particles. It oxidizes (dissolves) the gold and then uses another chemical to turn it into nanoparticles with which to dust itself.
Why does it do this? The answer to that question deserves the golden ticket.
It goes against what fungi is all about. Like other microbes — bacteria, viruses, algae and protozoa — it relies on a symbiotic relationship in a trade-off of needs. That means minerals and organic material that it can draw nutrients from, in turn, helping to recycle them, or cycle them about the Earth.
Somehow, this single-celled organism has an impact on the most stable element; the one prized in many practical applications because it doesn’t corrode (oxidize).
“Fungi can oxidise tiny particles of gold and precipitate it on their strands — this cycling process may contribute to how gold and other elements are distributed around the Earth’s surface,” geo-microbiologist and lead study author Tsing Bohu said in a news release.
“Fungi are well-known for playing an essential role in the degradation and recycling of organic material, such as leaves and bark, as well as for the cycling of other metals, including [aluminum], iron, manganese and calcium. But gold is so chemically inactive that this interaction is both unusual and surprising — it had to be seen to be believed.”
In their report, published in the journal Nature Communications, the scientists admit they don’t understand the relationship with gold — what they call the biogeochemical interaction — because there really should not be one.
Yet, the study proved gold-dusted spores grew faster and larger than fungi that doesn’t interact with gold. The theory is gold serves as a catalyst that helps the fungi digest certain carbon-based nutrients.
Researchers are excited to delve further into the mysterious pairing, hoping a better understanding will be a boost toward their primary goal; a simple way to find gold deposits. Because no one is going to get rich scrapping gold particles from ground cover, and they’d look pretty silly carting around a microscope to detect the nanoparticles.
In all seriousness, sampling within a larger study and tracking golden spores could bring that hoped-for treasure map into play.
CSIRO’s primary focus, as an independent federal government agency, is to improve the economic and social performance of industry. The gold mining industry, showing so much production and potential just a year ago, is seriously flagging. Restoring it is vital.
Mining of its wealth of natural resources ranks high among industries that support Australia’s economy. It is second in the world in gold production (behind China). Plenty of remote land remains to be explored and more than $120 billion has been invested in new projects.
But from a 2018 production peak, miners are scrambling to find new and elusive deposits.
Chief research scientist Dr. Ravi Anand said the industry was already using innovative exploratory sampling techniques to look for traces of gold in organic material, such as gum leaves and termite mounds, as clues to potentially large deposits underground.
“We want to understand if the fungi we studied, known as Fusarium oxysporum — and their functional genes — can be used in combination with these exploration tools to help industry to target prospective areas in a way that’s less impactful and more cost-effective than drilling.”
At the same time, other practical applications are being explored that could give new meaning to the word mining. Imagine, an organic material that can be used as a tool to efficiently and economically extract gold from waste, such as electronics, or to suggest new approaches, such as filtering gold from sewage.
It's pretty fascinating to look at the ways the stuff of nature moves and makes the connections that allow it to thrive. Seeds fly on the wind to propagate plant species. Dust from an ancient lake bed in the Sahara Desert travels on air currents over the Atlantic Ocean to fertilize the Amazon rainforest. Water, as it moves about the planet in any of three states of matter, is another obvious conductor of elements, including moving dissolved gold toward the surface through lava channels.
It seems the shadowy, and not so secretive places continue to reveal ways in which fascinating symbiosis comes into play.
Karen Bartomioli is a photographer and journalist specializing in freelance investigative reporting. She lives in Connecticut, and on the web