Future proofing with fungi

Fungi are a kingdom of their own, neither plant nor animal. They’ve been around for millions of years. They sustain plants and are crucial for making soil and keeping life going. But we’re only just starting to realise how much more they can do.

Harnessing ancient relationships

More than 400 million years ago, to make the transition from water to life on land, plants needed a little help. Fungi provided the essential minerals they needed before plants evolved roots and could obtain nutrients from the soil themselves.

“No organism lives in isolation,” explains Natural History Museum scientist Dr Silvia Pressel. The associations between plants and certain soil fungi, called mycorrhizal fungi, remain crucial. They’re an example of mutualism – a relationship that’s beneficial for both partners.

“The fungi’s thread-like filaments intertwine and colonise plant roots,” Silvia explains. “Plants provide fungi with sugars and lipids produced by photosynthesis.”

“In return, fungi provide plant roots with soil nutrients such as nitrogen and phosphorous,” adds Silvia, as they can penetrate the soil much better than plant roots.

These interactions are quite sensitive and can be impacted by environmental changes.

“Farming practices such as selective breeding and the use of chemical fertilisers has disrupted and replaced these mutualistic associations in our crop plants,” says Silvia.

Fungi over fertilisers

Artificial fertilisers are very harmful for the environment. They rely on mined minerals, including phosphorus. Not only is this a depleting resource but its production generates huge carbon emissions. The use of these chemicals damages soils and pollutes waterways.

Silvia is studying how we could harness the ancient relationships between plants and mycorrhizal fungi to improve food production and reduce our reliance on chemical fertilisers. It could shape the future of farming and help tackle our growing food supply challenges.

Fighting fungi with fungi

“When crops aren’t grown in association with their ancestral mycorrhizal fungi, they become vulnerable to diseases,” adds Professor Irina Druzhinina, a fungi researcher at Royal Botanic Gardens, Kew. Fungal pathogens pose a threat to crop yields and food security.

“This leads to a reliance on using chemical fungicides to protect crops, which can have negative environmental impacts and affect food quality,” says Irina. So, interest in sustainable alternatives, including biofungicides (usually specialised bacteria or fungi), has surged.

Beneficial fungi, such as the Trichoderma genus, reside in soil and activate plant immune systems. They compete with harmful fungi, producing substances that hinder their growth, and can also attack and kill them.

Farmers can use this strengthening of a plant’s defence mechanisms to improve crop resilience naturally.

Fungi are proving critical for addressing many global challenges. As well as boosting crop production while reducing the environmental impact of farming, they could also help us tackle our waste problems.

A solution to plastic pollution?

Some fungi have evolved to break down tough natural polymers, such as the cellulose found in plants. But while cellulose has existed for millions of years, plastic – which is a synthetic polymer – is barely a century old, and it poses a problem for nature’s recycling system.

Plastic’s resistance to degradation stems from its structure, which is hard for fungal enzymes to latch onto.

Cellulose was also “once very resistant to degradation,” says Irina. “This contributed to an accumulation of plant matter that over millions of years turned into fossil fuels.”

Irina continues, “microbes, mainly fungi and bacteria, eventually learned to feed on cellulose. We can expect the same thing will happen for plastics, but it will take millions of years for this adaptation to evolve. We don’t have time to wait.”

Certain fungi already break down substances like cutin, a waxy substance that coats leaves and has a similar structure to plastic. These fungi can also “deal with plastics” says Irina, “but it’s slow and incomplete, as it’s not the enzyme’s main function”.

Giving nature a helping hand

Irina continues, “we’re using our understanding of microbial evolution to speed up nature and develop a way to break down plastic”. Irina’s approach involves seeking microbes adapted to deal with cutin and then identifying the enzymes behind this process.

The next steps are to tweak the enzymes using protein engineering so that they break down plastic more efficiently and then produce them in a cell factory of yeast or bacteria. “These emerging technologies could revolutionise waste treatment within the next decade,” shares Irina.

She explains, “right now, plastics can usually only be recycled a few times before their quality degrades too much. Microbial enzymes would cut the plastic polymers into their building blocks, monomers. These can then be used over and over to produce new plastic products.”

Irina believes that “plastic is our friend, not our enemy”. She adds, “it’s a really useful material, but we need to change how we use and value it while also looking to solutions like fungi to tackle our plastic waste”.

An exciting tool for tackling global challenges

In addition to fungi’s potential to help crop production and fight plastic pollution, researchers are investigating their capacity to clean up oil spills and contaminants, such as pesticides, pharmaceuticals and heavy metals.

Silvia and Irina stress the importance of studying and protecting fungal diversity.

“There’s so much still to discover,” says Silvia. “It may hold the key to further solutions to our current planetary crisis.”

Nature-based solutions offer hope

Irina concludes, “fungal diversity is directly linked to our wellbeing and the technologies that can essentially improve our life”.

Fungi are a clear example of the benefits of working with nature to tackle our planetary emergency and create a more sustainable future.