Curious Conversations, a Research Podcast

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Travis

Have you ever heard that fungi might be able to influence the weather? I had absolutely never even thought about that until I read some recent research from Virginia Tech's Boris Vinatzer where they found a fungi protein that could help accelerate the formation of ice in clouds and possibly could be used to enhance precipitation. I of course had a ton of questions and Boris was kind enough to join the podcast to answer all of them.

Boris is a professor in the School of Plant and Environmental Sciences at His research includes molecular plant-microbe interactions, molecular evolution, and the taxonomy of plant pathogenic bacteria. He's also interested in investigating environmental microbes that might play a role in the formation of precipitation. And that latter piece is exactly what we talked about, specifically related to the fungi protein that he found.

He explained to how ice is actually formed and the role that accelerants play in getting water molecules in the appropriate places to actually freeze. And he also shared the role that then that plays in the way precipitation forms and then later falls to the ground from clouds. He shared what they found with the fungi protein related to both of those and the possible applications that this could have not only for cloud seeding and weather, but also some industry applications like flash freezing food or possibly even human organs that are later used for transplants. So it's quite possible that I have been shortchanging fungi this whole time, but you'll have to listen to the whole podcast to figure that out for sure. I'm Travis Williams. And this is Virginia Tech's Curious Conversations.

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Travis

I want to talk to you a little bit about fungi and how really how we might be able to influence weather using fungi through some discoveries that you made. But I was thinking maybe a good place to start is maybe to simply give folks a better understanding of what we're talking about when we talk about fungi. And the reason for this question is because when I mentioned it to my wife, she was like, does that mean we can put mushrooms, we're throwing mushrooms into clouds? And I was like, I don't think so, but maybe. So what are we talking about when we're talking about fungi?

Boris

All right.  Right, that's actually a really good question. When we talk about fungi, right, that includes the mushrooms that we see in the woods, and it also includes the molds that you see on old food growing. And so now when we talk about fungi in this context, it is really about the molds. It's not about the mushrooms.

Travis

Okay, well that will help her clear up. I think maybe we had seen too many ads for the Super Mario Brothers movie that's coming out. So maybe mushrooms were just kind of stuck in there. Well, I know you all did some work and you found a protein that could catalyze ice formations at sub-zero temperatures, was my understanding from the paper. And so I guess I'm curious, what does that mean? What does it mean to catalyze ice formations?

Boris

Right. Yeah, that's a really important question. Right. And it really starts from our misconception about the temperature at which water freezes. Because we generally just assume and learn in school that the temperature of water at what water freezes is zero degrees Celsius. But that's the temperature at which water starts melting. And I think we all know when we put water in the freezer. It's not that we open the door a minute later and it's frozen, right? It's still liquid. and in the freezer it's like minus 20 degrees Celsius and it takes a long time for that water to freeze. So, pure water, if you have a suspended droplet of pure water, that actually freezes at minus 40, 40 degrees Celsius. And that is because if you think, if you kind of zoom in into a water droplet and then you see all these water molecules, the individuals H2O, like one oxygen with two hydrogen atoms, and they just all move around. And it's not that we lower it to zero degrees Celsius and they just all stop and form a crystal. They want to continue moving around. And so if there's nothing else in the droplet, they continue moving around until there's really, really low temperature. But if we have something in a water droplet that can trigger those water molecules to get into the right place to form an ice crystal, then ice formation can happen at much higher temperature, like at minus two, minus four degrees Celsius. And so some bacterial proteins and fungal proteins, they have that function that when they are in water, they can make the water molecules start arranging themselves into something that looks like a crystal and then they start freezing.

Travis

Wow, it sounds almost like a room full of kids that you need to settle down for nap time. And the protein that you all found, it helps kind of do that and get them in the right place and they can be into a crystal. That might be a terrible analogy, I don't know.

Boris

I think that's a great analogy. And actually you could maybe think about it, not just kids, but if you have a room full of people and they just walk around and then you have, and then the ice nucleation protein is like the rows of chairs and then you, you know, and then people sit down and now they form a nice pattern based on the chairs. So the protein provides the chairs for the water molecules to sit down and form the crystal.

Travis

And so you all found a protein inside of fungi that will help do that or help do it faster. I guess the question I should ask is what exactly does it do?

Boris

Yes, right. So it does it at a higher temperature, right? So it doesn't do it above freezing. Like nothing can make water freeze above freezing temperature, above zero degrees Celsius. That does not happen. But as I started explaining earlier, like when we lower the temperature, water molecules will continue moving around on a very low temperature. So what these proteins do is to just raise the temperature at which the water freezes. And I can just add to that what we knew already about bacteria. Because bacteria that have proteins with that activity, have been known for many years. This was in the early 1980s that we figure that out. And these bacteria produce a protein that they do secreted to the outside of their cell, but it doesn't detach from the cell. It stays attached to the surface of the bacteria. And then these proteins actually form a cluster, one next to the other, and form a pretty large cluster. And then the water molecules we think there's actually not strong experimental evidence, but the model is that then water molecules arrange on the surface of this cluster of proteins just at the right distance as they are in an ice crystal. So they may form a sheet, single molecule sheet of ice on that protein. And then from that single sheet of ice, it grows and all the water around the bacterium starts freezing.

We did not know until recently how fungi do that. We knew from the early 1980s that fungi can do the same thing, but we didn't know what the protein was. And so in this study, we found out that fungi captured some point during evolution, the gene from the bacteria and built it into their own chromosomes, into their own genetic material and they use a similar mechanism now, but we can talk more about that, how that works.

Travis

I’m curious about that, I'm also, guess, probably maybe the next thing that I'm kind of curious about is how do these ice formations, what role do they play in the weather that we end up getting on the ground if they're happening in clouds?

Boris

So what is really well known, established for many, years in atmospheric science is that that process of something triggering the transition from liquid water to ice in clouds is a key step in the formation of precipitation. So that is well known and it's, and I start first thing when it's not needed, like when you have a summer thunderstorm and it's really hot and you have all this water evaporating from the surface. And then it goes up into the atmosphere really fast. There is so much water that these water molecules bump into each other just because there's so many of them and so crowded. And then they grow into larger and larger droplets until they are so heavy that they start falling down. But when we don't have a thunderstorm and we have a cloud, you just have a lot of little droplets. And that's why the cloud is white or gray. We cannot look through it because there a lot of small water droplets. Those water droplets, they don't really want to grow. They just hang out there pretty small and they're too light to fall down as rain. So, you know, we always think it's just normal that the cloud at some point starts raining, but it's actually not normal. Like a cloud would tend to not rain. But if we have an ice nucleator, which may be a bacterium or a fungus or some dust that we can talk about more, but anything in those cloud droplets, if that they can help the freezing, then now you have a droplet that's frozen. So while if You have a liquid droplet, you have water molecules, the water vapor, they may hit that little droplet, but some others leave the droplet. So you have this equilibrium of these tiny little molecules bumping into a water droplet, leaving your water droplet. Then the water droplet stays the same. But if the water droplet is frozen, like a snowball, and you can imagine if there's a small water molecule hitting that snowball, It's trapped. It can't go anywhere anymore. And so now that frozen water droplets starts growing and growing and growing until it's so heavy that it starts falling down from the cloud. It melts and becomes a raindrop. So that's the typical start of a raindrop in temperate climates when we don't have a thunderstorm. So we need something that triggers the freezing of this water droplet in the cloud so it can grow into and fall down.

Travis

That's amazing and it sounds like that this new protein that you found can do that. I'm curious what makes it potentially different because you've mentioned bacteria and maybe some dust and other things that might also accelerate that, but what would make this different from maybe those accelerants?

Boris

Right. that, as I said, so this happens in clouds all the time. But what we actually don't know is what are the particles in clouds that do that? There's some atmospheric scientists, motor biologists, they hypothesize this is bacteria and fungi that really contribute to the rain formation. But there's no proof. And there's no knowledge what the relative contribution of dust compared to bacteria and fungi. What we do know is that bacteria and fungi are present in clouds. And fungi and bacteria are much more efficient at making water freeze, at catalyzing this freezing. So this, what makes this fungal fungi, these fungi so special is that they secrete the ice nucleation protein out of the cell and it doesn't stay attached, but it goes into an environment around them. And so they can just, so a single fungal cell can make many, many ice nucleators that just go into an environment. And so we have both that this is a very efficient protein that makes water freeze at high sub-zero temperatures and it can produce a lot of them. So the combination of those two makes this very efficient. And although we don't know yet how in nature, how important these fungi are, we think that if we can produce enough of these fungi that we could use them to make clouds rain more, like to seed clouds.

Travis

Yeah. So are people doing some of that cloud seeding already with other types of things? I don't really know very much about cloud seeding. I hear some about it, but I'm curious, like what's the status of cloud seeding right now?

Boris

Yeah, yeah, right so cloud seeding has been considered kind of a pseudoscience because we didn't have much evidence that seeding clouds with fungal bacterial or other ice nucleators that make water freeze really had an impact on these And what has been used for long time is silver iodide. And it's very efficient but it's also very toxic. You know, some people say, okay, if you just, the quantities we spray into cloud is so low, so the concentration is low. doesn't, it's not a problem for the environment, but still it's highly toxic. So that's one limitation. And although we have used it for long time, the evidence was missing. But then there was a long campaign for like 10 years in the Rocky Mountains where they compared always an area where they use cloud seeding and one where they didn't. And they found a statistical significant increase in rain in one area where they seeded the clouds compared to the other one. So we have now scientific evidence that cloud seeding does work. But of course, it only works if everything else is there, right? You need a cloud with pretty high humidity. If the only thing missing are the nucleators, then you can see the cloud and you can make it rain. If there's no cloud, the cloud doesn't have enough water in it. You can put it for whatever you want in the cloud. It will not start raining.

Travis

So not a magic pill for rain, could make it could accelerate ⁓ The rain production that makes a lot of sense in it It would make sense to that, you know, even if what they were using might not be considered super toxic because of the levels are using or whatever But it always sounds like to have a non toxic option would be maybe a better alternative At least that's probably the one I would choose if I had to choose between the two

Boris

And it is even more active than the silver iodide, so the fungal proteins. But the question is, yes, is really can we produce enough of them cheaply enough to use them? That's a big question.

Travis

Well, I know that the weather part of this equation is the one that was really attractive to me, but I also know that there are some other applications to this work, some other areas of life where maybe making ice, turning water into ice faster could be very helpful to us. What are some of those?

Boris

Right. yeah, one, actually one related application. That is where the bacteria have been used for many years. That is in snow making, right? So it's not making the rain or snow in the clouds, but in the ski resort, it's like beginning of ski season. didn't snow and it's just a little bit too warm that water would just freeze if you spray it out over the ski slope. But now if you add an ice nucleator to that water and it's just below freezing, maybe you can make nice snow and you save the season and people can go skiing during winter break. And so there's a company that has produced the bacteria with ice nucleation activity for many years and it's a commercial product. Another application is in food production. And one example that I think is, is, is, fascinating. I never thought about is when you make concentrated fruit juice, like the fruit juice, you have to separate all the sugar and the other components of fruit from the water that's in the juice to concentrate it. So what, what is done is you have repeated freeze melt cycles and each time you separate the water from it. So if you can make the juice freeze at higher temperature more easily, and so you can really make that fruit juice concentrate more efficient. Another thing that is not really because we haven't had any ice nucleator is really to preserve any tissues, anything biological at low temperature. Because the problem is when you freeze something on one hand, right, you kind of maintain it, but you also usually disrupt, you kill that tissue because When you lower a temperature, you have all this ice crystals that form and usually just it's not viable anymore. So if you have an ice nucleator outside of a cell, then the water freezes outside and kind of pulls the water out of the cells. And it's possible that that then can keep the cells. It doesn't damage the cells as much.

Travis

Wow, so from skiing to juice to maybe organs, there's a lot of applications here it sounds like, or a lot of potential applications. That's really cool. Well, I'm curious, where do you hope that this research goes in the future?

Boris

⁓ yeah, Yes.

Yes, I really hope that we can use it in all of these applications, right? So on the translational side, translating the science into a real benefit to people, industry. But maybe one, I just want to add one more negative aspect really of ice nucleation. That's the frost damage to trees especially fruit trees in spring, right? Every year, especially in Virginia, we have very few peaches and apricots and cherries. And that's not really why they don't grow well here. They do grow well here. But it's just at the time that they bloom that we often have a frost and it kills them, kills all the blossoms. So if we can, again, but I described with the preservation that we can make the water freeze outside of the blossoms. Now we can protect them more easily. So there may be a way to stop that freezing, the damage there as well.

Going back to the research, what I think is the most interesting question for these fungi now is what's the advantage to the fungi? Why did they acquire this gene from bacteria? If they acquired that gene and it didn't really confer a real advantage to them, the gene would have just disappeared again, But they kept it and they actually innovated on it. They made it secretable into their environment. So it must really confer a huge advantage to some fungi during their life. But there's not a single experiment. We don't know at all why. So finding out the why, I think that will be fascinating.

Travis

I think I would love to know more about that side of things. It's too bad with things like that, they can't just tell us why they did it. Because they're making it lot easier. But yeah, it'd be fascinating to know what advantage that gave them that they kept. Because it sounds like there's a lot of potential advantages for us that we can capitalize on if things work out.

Boris

Oh yeah, yeah. And you know, yeah, since it's possible that they protect themselves like I described earlier, so if the water freezes outside. But there may be other advantages that are even more important. And actually the other, the opposite question is why are there relatively few fungi and bacteria that have that activity? I think that's even more perplexing, right? So they...acquired it from bacteria. Some bacteria have it, but 99.9 % or more of all bacteria and fungi don't have it. So if it's such a great thing for some, is it, don't more of them have it? So that's, makes no sense, So anyway, there's a lot to discover to figure out the role of this activity in bacterial fungal life.

Travis

Yeah, well, we will welcome you back on when you figure out the answers to those questions, because it sounds like you are very curious about this, and that is the title of the podcast. So it's a perfect fit.

Boris

That sounds good,

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Travis

And thanks to Boris for helping us better understand his research that shows how fungi might be able to influence the weather. If you or someone you know would make for a great curious conversation, email me at traviskw at vt.edu. I'm Travis Williams and this has been Virginia Tech's Curious Conversations.

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