Stressed About The World? Take A Cue From Cyanobacteria

In turbulent times, it helps to hear stories of resilience. What can we learn from 3.5 billion-year-old bacteria that eat light?

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

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• 0:14Ira Flatow?

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• 0:33Flora Lichtman?

  Hey, it's Flora Lichtman, and you're listening to Science Friday. If you're feeling stressed about the state of the world right now, you are not alone. In a poll from the American Psychological Association, over half the people surveyed said they felt isolated, and more than three quarters say they are significantly stressed about the future of the nation. In times like these, what I crave are stories of resilience, stories that remind me that the world has been a mess before and others have found creative ways through it. So I bring you cyanobacteria. These guys have lived through conditions that resemble actual hell and have made it work.

• 1:18Flora Lichtman?

  How do they do it? And what can we learn from them? That is what we're talking about today with Dr. Daviki Bahia, a molecular microbiologist at Carnegie Science in Stanford, California. Daviki, nice to talk to you. And what do you think of my premise? You can be honest.

• 1:33Speaker 03

  I love your premise. I want to applaud you for bringing it right into the room that we are all stressed, everybody from humans to microbes. So I'm more than happy to tell you about how microbes do it. And maybe if the conversation goes that way, are there any lessons to be learned?

• 1:51Flora Lichtman?

  Yes, that is what I want to know. Are there lessons to be learned? And I want to be clear that I don't want to anthropomorphize bacteria. I want to microbialize us.

• 2:01Speaker 03

  Two thumbs up to that.

• 2:03Flora Lichtman?

  OK, cyanobacteria, they're your jam. Introduce me to them, like even starting with their name. I mean cyan as in blue-green, right?

• 2:12Speaker 03

  That's right. And I can't imagine a more appropriate way. If anybody hasn't seen them, you should go out into the open. You'll probably see them in any lake. Uh there this absolutely gorgeous blue green color. That being said, they're even more gorgeous when you break them apart. You see that there's all kinds of pigments in them. Uh they were called cyanobacteria, but before that they were called blue green algae. Blue green part, correct. Algae, not true. They're really this thing, another name for you, prokaryotes, which means they don't have a nucleus. It also sort of tells you that they're really ancient organisms.

• 2:52Flora Lichtman?

  Well, how long have they lived on Earth?

• 2:54Speaker 03

  About three and a half billion, that's B.

• 3:00Speaker 03

  Uh let me remind you, the Earth is only four and a half billion years. So they hopped on, however they did, not uh long after that, which is to me really miraculous.

• 3:13Flora Lichtman?

  Well, what have they lived through? I mean, the Earth has changed a lot in three and a half billion years.

• 3:19Speaker 03

  Um absolutely, so one can only kind of guess what life on Earth looked like at that time. And before I get too far into this, for anybody who really gets jazzed by this whole subject, there's this marvelous book called Life on a Young Planet by Andy Knoll. And I recommend it to anybody who really wants to find out the nitty gritty. But that being said, I mean, the la- the the world looked very different. There weren't any trees, there weren't any animals. It was basically a hot or warm bond. And somehow, life evolved. One of the very early, but not the earliest, was cyanobacteria. But I think what's absolutely incredible about them is,

• 4:03Speaker 03

  I like to call them, you know, life's frugal geniuses, because they took light and they took carbon dioxide, both of them, you know, more than you want.

• 4:13Flora Lichtman?

  Free.

• 4:13Speaker 03

  And managed, free.

• 4:15Flora Lichtman?

  Yeah.

• 4:15Speaker 03

  Free, plentiful, maybe too much. And they figured out this incredible thing whereby they could use the energy of light to make carbon backbones and from carbon backbones make amino acids, make proteins. You know, long story, into a cell that divides. In some cases, not in cyanobacteria, it can divide in a few minutes. So you can make a copy of yourself, just starting from these two plentiful resources.

• 4:45Flora Lichtman?

  Yeah, I mean, and that's not actually trivial to do, as we know, as, you know, human beings grapple with creating renewable energies.

• 4:52Speaker 03

  Absolutely. And I think, you know, we don't, we sort of skip over the fact that these guys have done it, and they do it silently and efficiently. Cyanobacteria cell is a micron. That's 100th the width of a hair, and it's doing all of this, which is basically getting inputs, getting outputs, dividing. I mean, just think about that for a moment. And then going back to your question, because I didn't finish that, was in the process of fixing carbon and doing photosynthesis, they also actually produce oxygen in the air. So we had an earth that had no oxygen. And these guys, over time, because that's one of the

• 5:33Speaker 03

  byproducts of photosynthesis, oxygenated our earth, right? So, I mean, that's a geological marvel. And you can see that in the fossil record, right? That's how we know.

• 5:44Flora Lichtman?

  That's geoengineering on a huge scale. Also, thank you, cyanobacteria.

• 5:48Speaker 03

  Yes, yes.

• 5:50Flora Lichtman?

  We said at the top that they, they lived in places that resemble hell. Is that true?

• 5:56Speaker 03

  Absolutely. I would agree. For anybody who's been to Yellowstone, and if you haven't, you should go, it is really like walking into hell. At least my depiction of hell, which is, I think, very Western. It's the idea of belching fire and brimstone and sulfur. And that's what you feel like. You feel you've gone back in time. And yet, when you look, I mean, when you go past the bison and all the microbes, as they're called, you see in all of these hot springs, these beautiful colors, which are basically microbes that use pigments to absorb light and then do photosynthesis. So they're there in hot springs, they're there in the Arctic, they're there wherever you care to look.

• 6:36Flora Lichtman?

  Wow. I mean, the fact that you can see them, and yet they're microbes, means that they're living in packs, right? They're living in communities?

• 6:45Speaker 03

  Absolutely. And I, I think that sort of takes, you know, the conversation in the direction I would love to go, which is, you know, to be facetious. No microbe is an island. So they don't live alone. They live in communities where, for example, let's go back to cyanobacteria. They do photosynthesis. They may make and fix enough carbon that they can use it to divide, but they're making excess of all of this. They actually release this into, you know, wherever they happen to be, in this case biofilms. Those biofilms become like little hot houses, in the case of, in hot springs, for other microbes to live.

• 7:24Flora Lichtman?

  They're feeding the community, David?

• 7:25Speaker 03

  They're feeding, yes, they're feeding the community. It's, I mean, it's not that these guys don't do anything, but they get a lot from the cyanobacteria. A word that's often used is something called keystone species. Somebody who gets the community going. And cyanobacteria are are one of those. So, yeah, it is a community and it's a community that is both sharing resources, producing resources, and it's stable. You know, it's it's living on its own.

• 7:58Flora Lichtman?

  Like a well-functioning co-op?

• 8:00Speaker 03

  And even if human beings weren't there with their microscopes and their DNA machines, they would still be doing their thing, I would hypothesize.

• 8:09Flora Lichtman?

  And and are these communities diverse? I mean, it sounds like it's not just cyanobacteria in them.

• 8:14Speaker 03

  It is not only cyanobacteria, although you can get ones where they're predominantly cyanobacteria. But then you get other, what are called heterotrophs, which basically get their fixed carbon from somebody else. But something I've gotten very interested in are other phototrophs, not the cyanobacteria that, you know, I love and respect, but other guys that have different groups of pigments. And then they do a more complicated metabolism. And I'm getting more interested in them because they are even, you might say, even more interesting because they can gauge the environment and do different things at different times. Cyanobacteria are like clockwork, right? Photosynthesis during the day, they become another animal at night.

• 8:58Speaker 03

  They're basically fermenting at night, right?

• 9:01Flora Lichtman?

  Wait, they're they're making booze at night?

• 9:03Speaker 03

  They're making booze at night.

• 9:05Flora Lichtman?

  They're the perfect organism.

• 9:08Speaker 03

  They are the perfect organism. You've got it, Flora.

• 9:12Flora Lichtman?

  I mean, in these communities, do different microbes have different jobs?

• 9:16Speaker 03

  Yes. And you might ask, well, how do you know that? These things that you know, you can barely even see them. What you can do is look at what they're making. And the way you can look at that is by something called transcriptomics, which is where you look at the RNA that they're making. And you can then, because you have the genomes to figure out who's doing what, you can track back in this community who's doing what. And we've just recently found really fascinating examples, what we call, you know, day organisms and night organisms and mixed organisms. And the reason for that is a heterotroph doesn't really need light, right? So it has a choice, depending on who it's feeding off,

• 9:58Speaker 03

  to do its maximal metabolism at different times of day or night. So it's this, as you said, it's a core, different guys doing different things and working off each other.

• 10:09Flora Lichtman?

  OK, this is one I want to get to. Stay with us because after the break, we're going to learn some lessons from these cyanobacteria. Don't go away.

• 10:19Speaker 00

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• 11:48Flora Lichtman?

  Okay, so, you know, I feel like to survive for three and a half billion years on a changing planet where the atmosphere is very different over time, the temperature is very different over time, whether you're in water or ice or on land is changing over time. They seem resilient. Is that true? Like, how do they compare resilience-wise to other organisms?

• 12:12Speaker 03

  I would say, that's a very good question. I wouldn't go, you know, dip deep into that quicksand of what's resilience in different microbes. I would certainly say that microbes have a way of kind of shutting down, you know, almost saying, well, this is not a good time for us. We won't divide, we'll just sit tight. And what sitting tight means is just surviving till you can grow again. And they can do this for months. And they don't actually sporulate, but they shut down. And I think talking about, you know, how we can think about that, if there are tough times, do you change your strategy? And they can.

• 12:54Flora Lichtman?

  Okay, so how do they change their strategy in tough times?

• 12:57Speaker 03

  Well, they do a number of things. One is they shut down a lot of proteins that they don't need. They turn on other genes that they do need. But basically, many of the strategies is to shut down metabolism that they don't need and turn on things that they do need. And so, for example, like I said about the phosphate, you have a whole store of it. If there's phosphate in the environment, they take in as much as they need, but they also take up more than they need. And then they have this system by which they kind of store it in a cupboard. It's called polyphosphate, for example. It sits there, they don't need it, but they've kept it. Now, hard times come. There's no phosphate in the environment next door. So what do they do? They start to break it down.

• 13:41Speaker 03

  They use something called a polyphosphatase that breaks it down and releases it into the cell. And they can do this for almost all the things that they need. For example, nitrogen is the same thing. Let me tell you, by the way, just so I am not ever feel bad about this, they can actually fix nitrogen from the air.

• 14:01Flora Lichtman?

  When you say fix, you mean grab it?

• 14:03Speaker 03

  They get, they grab it and they make it into a form that you can use, right? You can't use nitrogen. But if you want to get it into a cell, you can make it into something called ammonia. That can be so-called fixed. In other words, the cell can use it, everybody else can use it. So not only are they using carbon dioxide, they're using nitrogen. And nitrogen, of course, is one of the major, you know, building blocks for life. So, I mean, that's the theme. When you have something, you grow. If you have excess of it, you store it. And then when hard times come, there it is. Not for just for yourself, but possibly for others, which I find, you know, remarkable.

• 14:43Flora Lichtman?

  Yes, that is a lovely sentiment. It sounds like the other thing that they do is sort of shut down operations that they don't need to have going on when they're stressed.

• 14:54Speaker 03

  Absolutely.

• 14:54Flora Lichtman?

  They simplify their life a little bit.

• 14:56Speaker 03

  Absolutely. And that sort of genetic network, I mean, we can get into that. But it actually tells you, I think, something remarkable that over evolutionary time, they've kind of figured out this ability to do things, right? To have this hierarchy of responses.

• 15:16Flora Lichtman?

  Which seems very sophisticated for a, a single-celled organism.

• 15:20Speaker 03

  You take the words out of my mouth. I mean, they are beyond sophisticated. You know, I, I, it actually makes my, you know, it, it really lights up my life to think how sophisticated these mechanisms are because they're actually doing this at a molecular level, figuring out how much there is, how much to shut down. And then boom, when something changes, they have a genetic mechanism, a molecular mechanism, to ratchet up and down, right? And they're doing this not just because that's the only thing going on. There's a hundred other things going on. And that's, I believe, you know, I mean, the acme of sophistication.

• 16:00Flora Lichtman?

  Wait, why is that the acme of sophistication?

• 16:02Speaker 03

  Yes, I mean, great question. I think it's the acme of sophistication because it is taking many, many inputs and then making a decision about what to do.

• 16:14Flora Lichtman?

  Hmm.

• 16:15Speaker 03

  Right? I mean, if we have something happen to our lives, right? It's one thing, it kind of takes over. These guys are dealing with this fluctuation, changes. Let's give an example of light, right? Light is changing through the day and night. Suddenly, there's too much light, right? There's too little light, the clouds come in. You can't just sit there, do nothing. You have all these systems that are A sensing the light and then telling the cell what to do. But it's not just light, right? At the same time, they may have run out of a nutrient. At the same time, a virus may have attacked them. That is all going on in this tiny little cell, making no noise at all, but going about its business, right?

• 16:57Flora Lichtman?

  It is amazing. I mean, when you say it that way, I'm like, wow, I have decision fatigue around, you know, what to cook for dinner tonight, you know?

• 17:05Speaker 03

  Exactly. And I think that, you know, if we were to go down the route of, well, how do you microbialize? It's this idea, I think, of decision making. And I think, you know, if you really sort of go philosophical on anybody, you could say, you know, how many decisions do we make rationally? And how many decisions do we just make? And that, I think, is a big difference, right? The important thing is, how is it, in my view anyway, understanding microbes is, how is that architecture so robust? You can't make mistakes, or not too many. You know, if you, if you muck up, you're dead.

• 17:46Flora Lichtman?

  Yeah, if you muck up, you're dead. What other lessons do you take away from them?

• 17:51Speaker 03

  Good question. I, I would say, for me, what's amazing about microbes is, how much is going on that as, as a society, as human beings, we just totally ignore? I mean, you know, if you shut down microbes tomorrow, we would not be here. But you know, that's, I, I mean, if you, you, if you poll the average person, even me, I don't think I would really say, well, you know, it's microbes that are keeping me alive. But in fact, they are. And I think we've really only touched the tip of the iceberg about all the things that they do. Right? And I think that's something that absolutely I would love. I mean, I would love to be a hundred years from now.

• 18:34Speaker 03

  Because we are still going, you know, organism by organism, gene by gene, we're getting better at it. We're looking at genomes, we're looking at communities. But we really don't know how these systems work together. So I don't know if it's a lesson for me, it's a lesson for science.

• 18:52Flora Lichtman?

  Yeah, yeah. Yeah, where will we be in 100 years?

• 18:56Speaker 03

  Where will we be 100 years?

• 18:59Flora Lichtman?

  Thank you so much for joining me today. I really enjoyed it.

• 19:02Speaker 03

  Thank you so much, Flora.

• 19:04Flora Lichtman?

  Dr. Deva Kipahaya, a molecular microbiologist at Carnegie Science in Stanford, California. This podcast was produced by Rasha Aridi and Kathleen Davis. Stay strong, everybody. We'll see you next time. I'm Flora Lichtman.