Just 150,000 of the world’s estimated 3 million fungi varieties have been identified. (Supplied: SA State Herbarium)
The word ‘fungi’ may conjure up thoughts of mushrooms on pizza, or cartoon-like red and white spotted toadstools poking up from the forest floor.
But fungi also gives us bread, wine and cheese, provides the foundation of many pharmaceuticals, plays a critical role in ecosystems — and could hold the key to plastic recycling.
There’s an estimated 3 million varieties of fungi around the world — but the vast majority are still largely unknown to science.
Dr Tom May, a senior mycologist at the Royal Botanic Gardens in Melbourne, says that’s partly because the fungi we can see is just “their spore producing structure”.
“That is just the tip of the iceberg,” he says.
“The feeding and growing part of the fungus is hidden away as very, very fine threads; microscopic threads in soil or wood.
“And that mass of fine threads — which we call the mycelium — can be enormous.”
Mycelium is the furry, weblike substance that grows off fungi. (Flickr: Vincent L (CC BY-NC-ND 2.0))
A single mushroom, for example, can have a mycelium that extends as far as a hectare underground.
“They can get into all the nooks and crannies, right down in amongst the soil particles, and they can extract nutrients and water out of those little crannies in the soil,” Dr May says.
Like animals, fungi forage for food
Dr May says we need to take another look at how we define fungi.
While they have “been lumped in with plants in history”, they’re actually “fundamentally different”, he says.
“They are a completely separate kingdom of the natural world,” Dr May says.
“They are actually more closely related to animals, to us, than they are to plants.”
Unlike plants, fungi can’t create carbon compounds through photosynthesis.
Instead, they have to get their food elsewhere, which Dr May says they do by “basically slobbering out over the substrate”.
“They are really good at breaking down organic matter — dead wood, leaves, bits of insects, feathers, whatever — and so they’ve got whole batteries of enzymes that they can use to do that,” he says.
Our forests would look very different if it wasn’t for a network of fungi breaking down organic matter. (Audience submitted: Karen Johns)
In that search for food, Dr May says, fungi do a very good job of cleaning up forest floors.
“If we didn’t have fungi and we walked through the forest, all of that dead wood and litter would just build up,” he says.
“It would be impenetrable, you wouldn’t be able to walk through the forest.”
An ‘undiscovered diversity’
To try and get a clearer picture of the world’s fungi, Dr May and a team of scientists recently compiled the State of the World’s Fungi report.
It found that of the estimated 3 million species on the planet, just 150,000 have been identified.
“I think it brings fungi out of the darkness a bit and it establishes a baseline for what our knowledge is at the moment,” Dr May says of the world-first report.
“It highlights this undiscovered diversity, and it also highlights the important roles, the benefits for humanity through agriculture and health.”
Dr May is now working to identify more fungi, so their many uses can be exploited.
“Each different fungus is trying to grow in its particular area to feed on a particular substrate, it has its own battery of enzymes and a lot of those have potential and actual industrial usages,” Dr May says.
His mission has been helped by a recent advancement in fungal taxonomy that uses DNA fingerprinting to identify species.
While it may be news to most that fungi have DNA, Dr May says “inside fungi there are little tiny bits of DNA that more or less are unique for each different species”.
He knows he is facing a mammoth task.
“As mycologists we certainly are not going to run out of things to do,” Dr May jokes.
“We’re not going to come into work and say, ‘right, we’ve done it, we’ve described everything’.”