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Chapter 1: What unique adaptations do fire-loving fungi have?
We work hard to strike the right amount of intelligence and ignorance. The Last Show with David Cooper.
Fungus, you gotta love it. So when I heard some mushrooms don't just survive wildfires, but in fact wait for them, sleeping underground, burying, and then eating charcoal, the after effects of a burn, I knew we had to learn more about it. And that's why Sydney Glassman, a microbiology professor at the University of California, Riverside, is here to talk about fire-loving fungi.
Chapter 2: How do wildfires impact forest ecosystems?
Or is it fungi? I don't know. Sydney? I like to say fungi, but either way works. Welcome to the show also. All right. Thanks for having me. Okay. Before we get to like genes and enzymes and cells, can you paint a picture for us? What happens to a forest right after a wildfire?
Chapter 3: What happens to fungi after a wildfire occurs?
I always imagine that like the forest was ruined. That's it. Life ends. I know that I'm wrong. Okay. Yeah. So it depends a lot on the severity of the fire, but let's say you have a high severity stand replacing fire where all trees die. So, which is our most trees die. So a lot of trees will die. It produces a ton of ash. A lot of nutrients are released. You have a higher pH, a ton of nutrients.
The wood is now turned into pyrogenic organic matter or charcoal. And then the upper layer of soil with all the bacteria and fungi is mostly dead. However, there are microbes that are in deeper layers in the soil that can move up and, or there are things that like have spores or like resistant propagules that could survive high temperatures that might have survived.
Chapter 4: How do fungi survive and thrive in post-fire environments?
And then there's things that basically were not there before the fire, but are able to bloom after the fire in absence of the competitors and other things that were there before. So there's this bloom of microbes that do really well after fires. This has actually been known about for over 100 years. There was a paper in 1909 that described these fireplace fungi.
And they're these orange cups that can sometimes make like a carpet of fungi across the soil. Like it can all be carpeted in these orange cup fungi if you have a really hot fire. Okay, and so this stuff just waits underground waiting for a fire. I always thought forest fire bad. Smokey the forest bear trying to prevent us from forest fires or whatever Smokey did. Hope he wasn't smoking.
That's bad for your health. But it turns out fires are not only completely natural, they kind of need to happen for our ecosystems to be balanced. Yeah. So in California and other Mediterranean ecosystems, fires are definitely natural and things are adapted to them. And there's whole books written about the plants and their adaptations to fire.
Chapter 5: What role do fungi play in forest regeneration after fires?
For example, they have underground tubers. They have thick bark. Some plants even have cones that require heat in order to release their seeds. So they actually require heat in order to reproduce plants. So there's whole books on this. We know a lot about plant adaptations to fire, but plants are all associated with microbes as well. And these fungi and bacteria also have adaptations to fire.
And that's basically what my career is about. What are these adaptations to fire and how are these microbes, both the bacteria and the fungi surviving and thriving after wildfires? That's what I want to know. I was in a pizzeria the other night. A piece of charcoal from the wood burning fire got on my pizza. I thought it was like burnt crust. I took a bite of it and my mouth still feels weird.
I cannot eat charcoal.
Chapter 6: How do fungi break down charcoal and pyrogenic organic matter?
Not good for me. But it's great for these funguses or fungi. How do they do it? How do they eat charcoal? So what we did with this study is we sequenced their genomes. And we found that they have a lot of them, not all of them, but a lot of them have a really increased genetic capacity to break down pyrogenic organic matter or charcoal.
So they have a lot of different genes and they've evolved the way to increase these genes in a lot of different ways. One is by gene duplication. So they basically just copy and paste and replicate their genes. So they have a lot more that enable them to break down charcoal. Another is through sexual reproduction.
So when I teach mycology, some students always think like, oh, I didn't realize fungi had sex. Actually, fungi have a lot of sex, and they have really different weird kinds of sex. Whoa, whoa, whoa, whoa, whoa, whoa, whoa, whoa, whoa.
Chapter 7: What are the reproductive strategies of fungi?
Don't gloss over this one. They have weird sex? Yeah, they're really famous for having lots of weird types of sex. They can have asexual and sexual reproduction. They can have, like, tons of different mating types where you might be able to have, like, 38 different... Instead of just, like, one male and a female, it could be, like, 38 different types of mating types.
So they have, like, a lot of different ways to sexually reproduce that humans or animals do not have, and that enables them to... survive a lot of disturbances. They can produce a bunch of different types of spores, sexual and asexual, a bunch of different fruiting bodies that can survive various disturbances.
So one way is through this sexual reproduction, they are able... Okay, so one thing that's really cool about Basidiomycete fungi is that they literally, instead of... We are all diploid. We have our genes from our mom and our dad, and they combine... And then we have two copies in our cells. What they do is they separate them.
And so they're literally separated by either a clamp connection or a septation where the two nuclei are separate. and they can have separate genes in them, and they can express different genes in these different nuclei. They only join really briefly, like basically at the moment of meiosis.
Chapter 8: Can fungi be used for environmental cleanup beyond wildfires?
I don't know why we're looking in the cosmos for aliens. We have aliens right here on Earth is what I'm hearing. Yeah, fungi are really cool. I mean, they really are really interesting. And then the last thing that also is my favorite is they actually were able to co-opt these genes from bacteria. So bacteria have really amazing abilities to... like all sorts of metabolic abilities.
And they are able to do horizontal gene transfer where they transfer genes from one organism to another. So like for us, we have vertical transmission. Like a mom gives birth to a baby. That's the only way you can transmit genes. But for bacteria, it's like, imagine you could share genes with your friends or you could share genes with other people in the room around you.
And usually they just do it between bacteria, but fungi, in this case, fungi took the genes from the bacteria. So this is like a very strange, rare cross-kingdom horizontal gene transfer occurrence where the fungi took the genes from the bacteria that enabled them to degrade charcoal.
Back to like them being dormant underground, how long can these fungi stay underground kind of waiting for a forest fire environment? Could they presumably like hundreds of years? Like they're just sitting there waiting? Potentially. Like actually one thing I really love about fungi is there's a lot not known about them.
So there's potentially five to eight million species of fungi out there and there's not very many mycologists. Like the Mycological Society of America annual meeting, like our largest annual meeting, might have like 250 to 500 people. So the amount of mycologists or fungal experts relative to species is low. And like, we actually do not know how long these things could be sitting around.
Like it's possible that if a forest doesn't burn for, you know, 50 or a hundred years, the sclerotia, these, these resistant propagules could be sitting there that whole time. And, um, We we there's very simply very limited research on showing like how long spores can actually persist.
And the other thing is, we don't know if they're like waiting in the soil for the fire or it's possible they could have dispersed in right after the fire. Now, the cleanup angle to me, this is fascinating to the funguses, the fungi, the fungal fungus. OK, whatever. You know the word. Do they come in after the fire and help the environment regenerate? Yes. Yeah.
So they are able to break down pyrogenic organic matter, to break down all this high amount of nitrogen and to make it into forms that are easier for other things to eat. And also they can rehabilitate the soil and they work on making the environment more hospitable for other fungi and plants to come in later. I got to ask one forward thinking question.
Could we use funguses like that to clean up our messes, not just forest fires, like industrial waste and stuff like that? I think there's a lot of potential for that. Cool. Well, Sydney Glassman is a mycology professor at the University of California, Riverside. Sydney, tell me how you really feel about fungus. You don't like it at all, I imagine.
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