It brings a new meaning to the phrase organic chemistry. Chemists have discovered that fungi can naturally absorb microscopic metal particles into their flesh in a way that could see metallic fungus used as catalysts or disinfectants.
Industrial catalysts often rely on processes that happen on the surface of metals, so tiny nanoparticles of catalyst with large surface-area-to-volume ratios are particularly effective. But such particles are only effective if they are prevented from clumping together using a chemical solution, which makes it difficult to separate the catalyst from the products of a reaction.
Now team at the Dresden University of Technology in Germany has discovered that fungi can assimilate and stabilise nanoparticles as they grow. Because the nanoparticles are immobilised on fungal filaments, they can be easily recovered later.
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Metal mould
Eychm眉ller鈥檚 team fed media containing gold, silver, platinum or palladium nanoparticles to common fungi, including .
After two months the researchers examined the fungi under a scanning electron microscope and found that the growing filaments had become coated in a crust of nanoparticles up to 200 nanometres thick. The newly bling fungi seemed unaffected by their metallic coat. One species could even cope with a coating of silver, known to be toxic to microorganisms, and used as a disinfectant in some clothing.
鈥淲e鈥檝e been surprised and impressed by [the fungi鈥檚] resilience,鈥� says Eychm眉ller.
Crucially, although the crust is much thicker than the individual nanoparticles, which are 10 to 20 nanometres across, the nanoparticles do not clump together to form larger particles. Since their surfaces are unobstructed, they retain their powerful catalytic properties.
Silver coating
As well as using metal-coated fungi as catalysts, those decorated with silver could be used for their disinfectant properties, says Eychm眉ller.
He thinks studying how fungi bind to the particles could also help understand why some organisms are prone to accumulating heavy metal pollutants. 鈥淭here ought to be reasons why a specific nanoparticle 鈥榙ocks鈥� to a specific fungus,鈥� says Eychm眉ller. 鈥淪o far not too much is known about interactions on that level.鈥�
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