Instant Genius - How fungi is vital to life on Earth

Episode Date: August 4, 2024

Mention the word 'fungi' and it’s likely many of our minds will turn to the mushrooms we enjoy sliced on the top of our favourite pizza or bowl of pasta. But there’s more to these fascinating organisms than this. Without fungi we’d have no yeast to make bread or brew beer and no penicillin to treat infections. In this episode, we catch up physician and immunology researcher Arturo Casadevall to talk about his latest book What if Fungi Win? He tells us about the essential role fungi plays in the ecosystems and lifecycles of the Earth, how they pose a potential threat to our food supplies, the role climate change is playing in the evolution of fungi and the role they may possibly play in combatting it. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Music just as the artist intended. Visit name audio.com to learn more. Hello and welcome to Instant Genius, a bite-size masterclass in podcast form. Every Monday and Friday, you'll hear wheel-leading scientists and experts talking about the most fascinating ideas in science and technology today. I am Jason Goodyear, commissioning editor at BBC Science Focus. Mention the word fungi, and it's likely many of our minds will turn to the mushrooms we enjoy, sliced on the top of our favourite pizza or bowl of pasta.

But there's more to these fascinating organisms than this, much more. Without fungi, we'd have no yeast to make bread or brew beer, and no penicillin to treat infections. In this episode, we catch up with physician and immunology researcher Archero Casadeeval to talk about his latest book, What, If Fungi Win. He tells us about the essential role fungi plays in the ecosystems and life cycles of the earth, how they pose a potential threat to our food supplies,

the role climate change is playing in the evolution of fungi, and the role they may possibly play in combating it. Welcome to the podcast. Thanks very much for joining us. Thank you for having me. You're very welcome. So today we're talking about your new book, What If Fungi Win? So let's start with the big question.

What is fungi and how does it differ? from other organisms? So the fungi, by the way, it can be pronounced fungi, fungi, fungi, fungi, fungi, fungi, and the readers should know that there is no wrong way to say it. It's what makes you comfortable and what makes people around you comfortable. So I tend to use fungi, but I would point out that what makes them different is that they are their own kingdom. What do I mean by that?

Animals are a kingdom. Plants are a kingdom. So the fungi are their own kingdom. That means that they are quite different and quite their own. So how do they differ from, say, mammals? So obviously they are very different from mammals. You don't see them walking around and you don't see them giving birth. But that's not the only way to look at it.

One way to look at it is to look at the DNA and to see how. similar they are. And it turns out that paradoxically, when you walk on the forest and you see mushrooms, they're closer to you genetically than they are to trees. So it turns out that the fungal kingdom and the animal kingdom are quite close. And we don't know exactly why we went to different ways. This happened a long time ago, but it's a fascinating element to the story. So how varied is their fungal kingdom. Oh my God, it's tremendously varied. There are at least six million species, and probably that's an underestimate, because people are not really going out there, looking for them, necessarily. So we are talking about millions. You compare that where

animals are much fewer species. So you mentioned there that they don't walk around and have babies and so on. So how do they proliferate? So they are actually, actually sexual organisms they mate. And when you see a mushroom in the forest, you're actually seeing the sexual element. What to keep in mind is that under the ground, that's where the fungi live. So there's an entire world under the ground. And you may see some representation of that when it rains and it's humid out. And then these mushrooms sprung out suddenly overnight. So what sort of environments do they prefer to live in then? They prefer to live in human environments.

I think the best example is you don't see them usually out in the field. You see them in the forest, in the shade. You see areas that are humid, cooler, shaded. And they play a really important role in the ecosystem. Could you explain that for me? So I think in the book I say that life without them wouldn't be possible. That's probably not right because you could still have bacterial life. What I really meant to say is that life without the fungi would not be possible as we know it.

Because what they do and the main job of this kingdom is it recycles nutrients. When a tree dies, you see the mushrooms growing in the world. They're digesting away the wood. They're releasing the carbon, the nitrogen. And these are then used by other organs. So the fungi are the big decomposers. They are the big recyclers. And they're essential for the life cycles on Earth.

So you came to study this field in a slightly unusual way, right? Could you tell us a bit about that? So I should tell my readers, I've never been trained as a my colleges. In fact, I don't consider myself an expert at all in the field of mycology. I came into this interesting defunuchy because, of my experiences as a doctor at the height of the AIDS epidemic, which in the 1980s and early 90s, you didn't have the drugs you have now, and the diagnosis of AIDS was a lethal diagnosis because many of the individuals would succumb, not to the virus, but to a fungus. The virus weakened their

immune system, and the fungus will then cause lethal infections. So I became fascinated, and actually very interested. At the time, I couldn't believe what I was seeing. I was seeing people a lot younger than I died, and we couldn't do anything about it. And I became very interested in working to see if something could be done to improve the treatment of fungal diseases. And that's how I came to work on the fungi,

and over the years I become more and more interested in this mysterious, unknown, and ignored kingdom. Yeah, so we'll get into the kind of infection part of the conversation in a while. But first off, they serve lots of useful purposes, don't they? Not only as food and as nourishment, but for use in the production of drugs, most famously penicillin. That's right. So penicillin, the cephalosporins, which is a huge class of antibiotics.

These are all made by fungi. But people who have high cholesterol, they take statins. The statins come from fungi. Now, there is a question as to why would a fungus be making a drug to lower cholesterol? No, the fungus isn't making the drug to lower cholesterol. What the fungus is doing is creating a chemical entity as part of their metabolism that happens to work in you to lower cholesterol. So they are very important sources of medicines. They also make other things like halucidates. For example, magic mushrooms. hallucinogenic mushrooms. LSD is a product of fungi. Yeah, so also lots of them are why we can eat lots of them. Personally, they're one of my favorite things to eat, but they can also really badly poison us. That's right. And I follow a very simple rule. The only mushroom I eat is the one that I

buy in the market. Simply because these organisms, if you get the wrong one, the poisoning can be fatal. There is a fungus here in North America. that known as Amanita Faloides and only a few mushrooms could kill you by basically making the liver fail completely. It's a terrible, terrible toxic. So I love mushrooms. I try to eat them as much as I can. I love the way they taste. I love the roughage. But I try to be very careful to make sure that I get them at the market. That's great advice. So you mentioned that. They have several very potent effects. And one thing that you talk about in the book is they're actually affecting crops that we eat. The major danger that the fungal kingdom poses to humanity,

my opinion, is not a brand new disease. It's the fact that our society is dependent on a few crops. Wheat, rice, corn. And most of our crops are in fact very, very high. homogeneous. Why? Because we selected rice to give us high yields. We selected wheat. And the fungi are the major passages of plants. And if a new fungal strain will emerge, for example, we'll take out two of the major crops at the same time. Humanity will have a huge trouble making up the calories. We just don't have the many calories out there. So it could really be devastating for humanity civilization if they basically wreck or crops. So obviously this is a serious threat.

So what can we do about it? Humans are really good at worrying about tomorrow, but they often don't worry about the future. You know, we worry, I don't know if I'm going to be alive tomorrow, so what are I worried about the future? But I think what we have learned is that the best protection against the long term is knowledge. the more you know, and particularly the more you know about the biology of its organisms,

the more likely you are to be able to develop countermeasures. As a way of digression, think about the COVID pandemic that we all live through. Within a year, there were drugs, vaccines, rapid tests. Why was that available? Because research have been done in the past that allowed the pharmaceutical industry and governments to move very rapidly to the, develop these things. So my short answer to you is we need to have better preparedness. We need, for example, to be studying them to figure out how to breed rice that is not susceptible to fungi

and the same thing to develop fungi so we can spread on the fields that don't harm other crops that are not carcinogenic. But that requires research and knowledge. And if humanity continues to do what he's doing, which is to invest in knowledge, I think we're increased the likelihood that we're going to be okay. So does GMO have a role to play in this? I believe so, although, as you know, it's a controversial topic in many countries. Here in the United States, GMO foods are quite common, but you can use genetically modified organisms to make them resistant to fungal diseases. And, you know, that is an ongoing dialogue. And my belief is that eventually we're going to have a better understanding of just both how safety are on what you can do.

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story. The bats in North America were fine until 2006. And then something happened by which a fungus was introduced in North America. Some people think that it may have been introduced from Europe on the boots of somebody who this is gave. And this fungus likes to grow in the cold. And the bats in the temperate climates, there is no insects in the winter. So what they do is they have learned survive by a hibernate, but they lower their temperature to about 12 degrees centigrade. And when that happens, the fungus can grow on them, and the fungus is killing millions of bats in North America and replenishing these populations. It's going to be very difficult because the bats don't make a lot of babies. They make like one baby per year or so. And we fear that some

bats species are going to go into extinction. But here is the interesting thing, Jason. If you take the infected bat and you're bringing it into the laboratory and you just feed it. They raise their temperature rapidly and when that happens is they clear the fungus. So temperature is really, really important part of the equation. Yeah. So related to that in the book, moving on from bats to humans, you say that humans and fungi have so far evolved a sort of truth. So what do you mean by that? I don't know if truth was the right word, but here is what I would say. I would say that most of us worry about viruses. We worry about bacteria.

You worry about like protozoa. You worry about things like malaria when you travel to a region that's malaria. But people don't really worry about the fungi, killing them. They worry about athletes' foot. They worry about getting a nail infection. They worry about having dandruff. But dandruff doesn't kill you. That, by the way, is a fungal infection.

And I've always been fascinated as to why. Why are we so resistant to this when the trees have so much trouble with them? When other animals that are like frogs and insects have all the trouble with them, and that led us so many years ago to propose that it was temperature that in fact help us keep the fungi away. Most fungal species in this planet cannot tolerate your temperature or my temperature, period. So just being warm provides this tremendous amount of protection. And you see it with the bats.

They hibernate and then they get into trouble. Having said that, though, you mentioned earlier patients with HIV. So why do immunocompromised patients become more susceptible? Okay. So it goes like this. Imagine that this enormous protection has two pillars. One of them is temperature and the other one is advanced immunity. So in the late 20th century, when cancer therapies got better, when people began to do transplants, we knew that that can happen, but it came at the price of immunity. So guess what? Fungle infections went out. So HIV fungal infections go out because temperature is not enough. But if you now have temperature and advanced immunity, then you get tremendous protection. Frogs have a good immunity as you do, but they don't have the temperature. So they are very

susceptible to a chytrate fungus that is killing them worldwide. We lost more than 100 fungous species. But again, if you can take the frogs into the laboratory and warm them up, you can cure them. And I saw a fascinating article from Australia where they try to save the frogs by creating frog soundness. So what they do is they put the frogs in a warm room and let the temperature do its magic. So we're talking about temperature here, and one of the biggest issues in science at the moment is climate change and rising temperatures around the world. So what impact is that having on this idea?

Well, first of all, I would point out that temperature is one of those things that affects everything. You change one degree, the temperature. All the cellular processes change. So what we're seeing already major changes in things like distribution. of fungi. As in the United States, there's a desert fungus known as coxioids, imitis, and it's spreading as the areas become warmer and drier. But the biggest worry I have is not that, because that deals with known threats. The biggest worry I have is that I don't really have days. All the organisms in the environment either have to adapt or they die. And when adaptation,

means that we may be losing this gradient that we have. In other words, if fungi adapt to really hot days and they adapt to human temperatures, then we're going to lose the protection that we're getting by just being warm because then basically then we only have immunity and then we may be as susceptible as to frogs. So what do we know about the ability of fungi to adapt? So we know that it's not hard that people have done experimental evolution in laboratories. You can take a fungus and you go to the incubator and you continue to raise the temperature a little bit every day. And if you do it slowly, you could train them. You could train them to grow a much higher temperatures. And in the book, I covered the situation with Candida Orris. Candida Oris is a fascinating story. It's a fungus that's

not known to medicine until 2009, is then recovered from the ear of a patient, and they gave her the name Oros, Latin for ear. The fascinating thing happens a couple of years later. In 2011, 2012, and 2013, the fungus emerges simultaneously in three continents. That is, begins causing disease in people in three continents. And these isolates are not related. It's not like somebody took a plane from Venezuela to South Carolina. Africa and brought the fungus with them. So something had to happen in the environment that this thing came out of nowhere and began killing people. Now, most of the people who died were immunosuppress. So it's not thought to be a danger to the general population, but still, these are debilitated

individual when the fungus gets in, it's very difficult to treat. And one of the issues that we've been thinking about is what is the common denominator between India, Africa and South America, that in the period of a couple of years could lead to this. And the only thing we can think of is climate change. So the idea is this fungus was out there in the environment. And then with more and more hot days, some of them adapted. And then they broke through the human heat protection. And they began to cause disease in individuals who were immunosurprised.

So on the other side of this coin, you talk about something that I'd never heard of, which is humans are getting cooler. Yes. I had never heard of that until I saw the report either. I thought that we couldn't get cooler. So it turns out that in a fascinating bit of work, some researchers had the great idea to collect all the temperatures from hospitals, any place that they could get their hands. So now, temperature is something we know how to measure. We know how to measure temperatures at the beginning of the scientific revolution. People can't say, well, you know, maybe the thermometers weren't good 100 years ago. No, we know how to measure temperature. We know the temperature in which water boils and water freezes.

And what they found was that on average, temperatures 100 years ago were warmer than they're now in people. What could be accounting for this? The right answer is, I don't know. But they speculate that 100 years ago we lived in a dirtier world, that there were a lot more. people walked around with more infections. There were more parasites. There were more tuberculosis and things like that. And infections cause inflammation.

And guess what inflammation does? It causes heat. So people may have been walking around with more chronic inflammation, and that could have given them, you know, another degree. But the worrisome thing here is that even though they say average human temperature is 37 degrees centigrade, 98 degrees Fahrenheit, height, that is an average. Some people are cooler and some people are warmer. And what I worry about is that the fungi are moving to getting hotter and we're moving a little cooler. And some people, especially those at the cooler end, there may be trouble ahead. Yeah, so we're heading to a potential

threat there. How serious is it? Well, I think it's potential. I don't know, you know, it's like everything else. You know, we've been worrying, for example, about bird flu every year. in the midst of a bird flu outbreak, unfortunately, it hasn't happened. So I don't think science and medicine can predict to you what is the probability that something is going to happen and it's going to happen this year. All that can say is it could potentially happen. So my view is, like just like bird flu, like we could potentially, you know, be in a new pandemic in a matter of weeks, or it may not happen. But I think the threat is there, and certainly the threat is much greater now that it was in the past because of climate change. So we've covered quite a lot there,

and I like at the end of the book you say there's still so much we don't know, which is, you know, the right approach in any field of science, really, isn't it? So what are some key areas of research that are top of the list, you know, the first things that we should be looking at? So I think that we don't have a good understanding of the role that fungi I play in the planet. I think we began by saying that the great decomposures, okay, fine, they break down stuff. But they also appear to be critical communities under the soil, and we don't see them. They're under the grass. They're under the trees. What are they doing there? There is also a belief that they may be trapping enormous amounts of carbon under the soil,

which is immediately that's one way to think about it is, well, maybe they can help us. So if you ask me, what would I like to know more? I would like to know more about the biology. Most of what we know comes from a couple of species, like Sacramizes cerebici that we love because we used to make bread and we used to make wine. But the majority of this kingdom is completely unknown to us. And I think it is a source of medicines. We can basically use it to help us, even more than is helping us already. Do you think it's being slightly ignored by researchers? Yes.

Go to a scientific conference and look at talks, especially a microbiology talk. And you can just begin to count the number of viral talks, bacterial talks, protozoal talks. It's ignored in many ways. And part of the issue, Jason, is it's not conscious. Look, the human capacity for doing science is limited. You imagine it's a total number of people can work on it. And the fungi come late at the story. They come at the late 20th century.

And people have been more focused on other areas. So the areas of science are not necessarily balanced. We don't all necessarily work on the relative importance of things. You're solving history, since people who work in one area, then to train others. But one of the ideas and writing this book was to make people more aware. Because if more people are aware, they will think about it. And if more people think about it, then it's likely that we can change the trajectory of fields. Thank you for listening to this episode of Instant Genius, brought to you from the team behind BBC Science Focus.

That was Arturo Casadevall. To discover more about the topics we've just discussed, check out his latest book, What, If Fungi, When? If you liked what you just heard, then please do consider subscribing to Instant Genius on your podcast platform of choice. The current issue of BBC Science Focus magazine is out now. Pick up a copy wherever you buy your favourite magazines or download us on your preferred app store. You can also find us online at sciencefocus.com. This podcast is sponsored by Name, Audio and Focal. The texture and emotional depth of music can be lost through digital sources or poor signal.

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