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Digging With DNA: Soil’s “Biological Fingerprints” Point to Hidden Diamonds

Researchers have pioneered a method to detect buried kimberlite, a diamond-associated rock, by studying microbial DNA in surface soil. This offers a non-invasive way to identify minerals deep underground, proving more precise than traditional geochemical analysis. The technique, with broader applications in mineral exploration, could redefine the future of the mining sector.

DNA sequencing methods can also assist in identifying minerals crucial for the transition to green energy.

Researchers have identified buried kimberlite, the rocky home of diamonds, by testing the DNADNA, or deoxyribonucleic acid, is a molecule composed of two long strands of nucleotides that coil around each other to form a double helix. It is the hereditary material in humans and almost all other organisms that carries genetic instructions for development, functioning, growth, and reproduction. Nearly every cell in a person’s body has the same DNA. Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA).” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>DNA of microbes in the surface soil.

These ‘biological fingerprints’ can reveal what minerals are buried tens of meters below the earth’s surface without having to drill. The researchers believe it is the first use of modern DNA sequencing of microbial communities in the search for buried minerals.

New Techniques, Big Potential

The research published this week in Nature Communications<em>Nature Communications</em> is a peer-reviewed, open-access, multidisciplinary, scientific journal published by Nature Portfolio. It covers the natural sciences, including physics, biology, chemistry, medicine, and earth sciences. It began publishing in 2010 and has editorial offices in London, Berlin, New York City, and Shanghai. ” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>Nature Communications Earth and Environment represents a new tool for mineral exploration, where a full toolbox could save prospectors time and a lot of money, says co-author Bianca Iulianella Phillips, a doctoral candidate at UBC’s department of earth, ocean and atmospheric sciences (EOAS).

The technique adds to the relatively limited number of tools that help find buried ore, including initial scans of the ground and analysis of elements in the overlying rock.

“This technique was born from a necessity to see through the earth with greater sensitivity and resolution, and it has the potential to be used where other techniques aren’t working,” said Phillips.

When ore interacts with soil, it changes the communities of microbes in the soil. The researchers tested this in the lab, introducing kimberlite to soil microbes and watching how they changed in number and speciesA species is a group of living organisms that share a set of common characteristics and are able to breed and produce fertile offspring. The concept of a species is important in biology as it is used to classify and organize the diversity of life. There are different ways to define a species, but the most widely accepted one is the biological species concept, which defines a species as a group of organisms that can interbreed and produce viable offspring in nature. This definition is widely used in evolutionary biology and ecology to identify and classify living organisms.” data-gt-translate-attributes=”[{“attribute”:”data-cmtooltip”, “format”:”html”}]”>species.

“We took those changed communities of microbes as indicators for the presence of ore materials, or biological fingerprints in the soil of buried mineral deposits,” said Phillips.

Real-World Testing and Promising Outcomes

Using these ‘indicator’ microbes and their DNA sequences, the team tested the surface soil at an exploration site in the Northwest Territories where kimberlite had previously been confirmed through drilling. They found 59 of the 65 indicators were present in the soil, with 19 present in high numbers directly above the buried ore. They also identified new indicator microbes to add to their set.

Using this set, they tested the surface soil at a second site in the Northwest Territories where they suspected kimberlite was present, and precisely located the topological outline and location of kimberlite buried tens of meters beneath the earth’s surface. This showed that indicators from one site could predict the location at another site. In the future, exploration teams could build up a database of indicator species and test an unknown site to find out if kimberlite deposits are buried beneath the soil.

Microbial Precision vs. Geochemical Analysis

The researchers evaluated their technique against another technique known as geochemical analysis, which involves testing elements in the soil to identify the minerals beneath. The microbes were more precise when it came to identifying the location of buried ore.

“Microbes are better geochemists than us, and there are thousands of them,” said lead author Dr. Rachel Simister, who conducted the work as a postdoctoral researcher in the UBC department of microbiology and immunology (M&I). “You might run out of elements to sample, but you’ll never run out of microbes.”

Broadening Horizons and Commercial Prospects

The technique, born from work by a team including Phillips, Dr. Simister, Dr. Sean Crowe, and the late professor Peter Winterburn, could catalyze the discovery of new kimberlite deposits. These rocks are known not only as potential stores of diamonds but also for their ability to capture and store atmospheric carbon. 

The technique has potential application across other metallic deposits. The team’s ongoing research shows similar results for identifying porphyry copper deposits.

“You could use this technique to find minerals to fuel a green economy,” said senior author Dr. Crowe, EOAS and M&I professor and Canada Research Chair in Geomicrobiology. “Copper is the most important critical element that we’ll need more of going forward.”

Dr. Crowe, along with Dr. Simister and co-author Dr. Craig Hart, co-owns spin-off company Discovery Genomics which provides these sequencing services to the mineral resource sector.

“This is exciting because it’s part of a growing recognition of the potential for using microbes at every stage of mining, from finding the minerals to processing them, to returning sites to their natural states,” said Dr. Crowe. “Currently, microbial DNA sequencing requires specific expertise and is comparable in cost to other mineral exploration techniques, but this could change with industry adoption.”

Reference: “DNA sequencing, microbial indicators, and the discovery of buried kimberlites” by Rachel L. Simister, Bianca P. Iulianella Phillips, Andrew P. Wickham, Erika M. Cayer, Craig J. R. Hart, Peter A. Winterburn and Sean A. Crowe, 21 October 2023, Communications Earth & Environment.
DOI: 10.1038/s43247-023-01020-z

Source: SciTechDaily