A gold-mining fungus

This article in Science news from the ABC reports on the discovery of a gold-mining fungus found near a major gold deposit in Western Australia. The article is a summary of this paper published in Nature Communications.


The paper describes a careful study of fungi and other microbes living in the soil of a gold anomaly near Boddington in Western Australia. (A gold anomaly is an area where higher than expected levels of gold are found near the surface. Anomalies often lead to the discovery of gold deposits.) The authors discovered that four species of fungi in their soil samples were able to dissolve, mobilise and precipitate gold nano-particles.


It's been known for many years that bacteria and archaea can concentrate, precipitate and sometimes immobilise many minerals in soils, from toxic heavy metals to gold. This is the first study to show that fungi form gold nanoparticles when growing in gold-rich environments.


One of the fungi discovered in the soil was a strain of the common soil fungus Fusarium oxysporum, called 'TA_pink1' on account of the pink colour of the growing hyphae. Fusarium oxysporum is a taxonomically very tricky fungus. It's very common in soils throughout the world, from equatorial deserts to arctic tundras. Some strains cause a range of diseases in plants.


A false-colour scanning electron microscope image of the gold-mining fungus Fusarium oxysporum isolate TA_pink1. Source: https://www.abc.net.au/news/science/2019-05-24/fungus-containing-gold-discovered-in-western-australia/11143230

Recent genetic studies, however, have shown that F. oxysporum is not one species, but rather is a complex of many scores of species, most of which are very poorly understood. There's still a great deal of important taxonomic research to do on 'Fusarium oxysporum'.


So F. oxysporum isolate TA_pink1 may well be a new, un-named species, which happens to have the remarkable property of using gold to grow and thrive, and precipitating it as nanoparticles. Of course, this study has only scratched the surface of its very significant potential uses.


The story of the gold-mining fungus shows why taxonomy is so important. Fusarium oxysporum is a complex of many species, all with different ecologies, physiologies, potential uses and real or potential threats as diseases. While all this diversity remains hidden under a single name, there is a real risk of confusion and error.


Fusarium oxysporum is a candidate for one of the world's most important fungi, and fungi are arguably among the world's most important organisms. That we know so little about it (and them) is one more good reason why we need way more taxonomy, and why documenting our biodiversity will bring benefits and surprises all along the way.

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