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Future proofing with fungi
The planetary emergency is a complex crisis that requires innovative solutions. We can find some of these solutions in nature.
From helping us grow our food to tackling our plastic waste problem, fungi offer opportunities for a more sustainable future.
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.
An illustration of warted amanita mushrooms by George Smith Worthington, 1866. We’ve just scratched the surface of fungi’s potential to help us tackle the planetary emergency. © Public domain image. Source: Library and Archives of the Natural History Museum, London.
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.
A magnified image of clover root cells colonised by a fungus called Endogone. They establish a mutually beneficial interaction, providing each other with nutrients. The slide is stained blue to make the fungal structures easier to see. © Silvia Pressel
“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.
A tractor spraying fertiliser on a crop. By harnessing natural plant-fungi relationships, we could reduce the need to do this. © stockstation/ Shutterstock
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.
By adding beneficial fungi to the roots of crops such as wheat and strawberries, we might be able to reduce our use of harmful artificial fertilisers. © Mykola Mazuryk/ Shutterstock
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.
This petri dish shows a biofungicide in action. The green fungus on the left is Trichoderma guizhouense. It fights the white fungus on the right, Sclerotinia sclerotiorum, which causes a disease in many plants. Outbreaks can be a serious problem for crops. © Irina Druzhinina, M Rahimi, RBG Kew
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.
This image shows moulds, including members of the Cladosporium and Alternaria groups, growing on polystyrene waste. Only some fungi and bacteria have the adaptations needed to degrade certain plastics. Scientists are researching how these fungi could potentially be used to deal with our plastic waste. © Kai Cartwright, Irina Druzhinina, RBG Kew
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
A selection of fungal cultures isolated from leaf surfaces for further investigation. Many microbes living on leaves have adaptations that enable them to digest plant waxes. Scientists believe these may also mean they can break down some types of plastic that are similar in structure to the wax. © Kai Cartwright, Irina Druzhinina, RBG Kew
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”.
A specimen of a fan-shaped oyster mushroom, Pleurotus ostreatus, a common edible fungus. Beyond some fungi being a tasty food source, this diverse group could also help us tackle global challenges such as pollution.
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.
