Stressed About The World? Take A Cue From Cyanobacteria

FLORA LICHTMAN: This is Science Friday, I’m Flora Lichtman. 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. How do they do it, and what can we learn from them? That is what we’re talking about today with Dr. Devaki Bhaya, a molecular microbiologist at Carnegie Science in Stanford, California. David, nice to talk to you, and what do you think of my premise? You can be honest.

DEVAKI BHAYA: I love your premise. I want to applaud you for bringing it right into the room, that we’re 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?

FLORA 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 a microbialize us.

DEVAKI BHAYA: Two thumbs up to that.

FLORA 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?

DEVAKI BHAYA: 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. They’re this absolutely gorgeous blue-green color. That being said, they’re even more gorgeous when you break them apart and you see that there’s all kinds of pigments in them.

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 tells you that they’re really ancient organisms.

FLORA LICHTMAN: Well, how long have they lived on Earth?

DEVAKI BHAYA: About 3.5 billion– that’s B. Let me remind you, the Earth is only 4 and 1/2 billion years, so they hopped on, however they did, not long after that, which is, to me, really miraculous.

FLORA LICHTMAN: Well, what have they lived through? I mean, the Earth has changed a lot in 3 and a half billion years.

DEVAKI BHAYA: Absolutely. So one can only 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 world looked very different. There weren’t any trees, there weren’t any animals. It was basically a hot or warm pond, 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, I like to call them life’s frugal geniuses because they took light and they took carbon dioxide, both of them, more than you want–

FLORA LICHTMAN: Free.

DEVAKI BHAYA: Free.

FLORA LICHTMAN: Yeah.

DEVAKI BHAYA: 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, long story, into a cell that divides. In some cases, mountain cyanobacteria can divide in a few minutes. So you can make a copy of yourself just starting from these two plentiful resources.

FLORA LICHTMAN: Yeah, I mean, and that’s not actually trivial to do, as we know, as human beings, grapple with creating renewable energies.

DEVAKI BHAYA: Absolutely. And I think we skip over the fact that these guys have done it, and they do it silently and efficiently. Cyanobacterial cell is a micron that’s 1/100 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 byproducts of products of photosynthesis, oxygenated our Earth. So, I mean, that’s a geological marvel, and you can see that in the fossil record. That’s how we know.

FLORA LICHTMAN: That’s geoengineering on a huge scale. Also, thank you, cyanobacteria.

DEVAKI BHAYA: Yes, yes.

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

DEVAKI BHAYA: Absolutely. I would agree. If anybody who’s been to Yellowstone, and if you haven’t should go, it is really like walking into hell, at least my depiction of hell, which is, I think, very Western, which is 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 macrobes, 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.

FLORA 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?

DEVAKI BHAYA: Absolutely. And I think that sort of takes the conversation into a direction I would love to go, which is, 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 wherever they happen to be– in this case, biofilms. Those biofilms become like little hothouses, in the case of hot springs, for other microbes to live.

FLORA LICHTMAN: They’re feeding the community, basically?

DEVAKI BHAYA: They’re feeding– yes. They’re feeding the community. 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 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. It’s living on its own.

FLORA LICHTMAN: Like a well-functioning co-op?

DEVAKI BHAYA: 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.

FLORA LICHTMAN: And are these communities diverse? I mean, it sounds like it’s not just cyanobacteria in them.

DEVAKI BHAYA: 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 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 like clockwork. Photosynthesis during the day, they become another animal at night, they’re basically fermenting at night.

FLORA LICHTMAN: Wait, they’re making booze at night?

DEVAKI BHAYA: They’re making booze at night.

FLORA LICHTMAN: They’re the perfect organism.

DEVAKI BHAYA: They are the perfect organism. You’ve got it, Flora.

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

DEVAKI BHAYA: Yes. And you might ask, well, how do you that? These things, 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, day organisms and night organisms and mixed organisms. And the reason for that is a heterotroph doesn’t really need light. So it has a choice, depending on who is feeding off, to do its maximal metabolism at different times of day or night. So it’s this– as you said, it’s a co-op. Different guys doing different things and working off each other.

FLORA LICHTMAN: OK, so I feel like to survive for 3 and 1/2 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? How do they compare resilience-wise to other organisms?

DEVAKI BHAYA: I would say– and that’s a very good question, and I wouldn’t go deep into that quicksand of what’s resilience in different microbes. I would certainly say that microbes have a way of shutting down, 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 how we can think about that, if there are tough times, do you change your strategy? And they can.

FLORA LICHTMAN: OK, so how do they change their strategy in tough times?

DEVAKI BHAYA: 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, 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 store it in a cupboard. It’s called polyphosphate, for example. It sits there. They don’t need it, but they’re kept it.

Now hard times come. There’s no phosphate in the environment next door. So what did they do? They start to break it down. 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.

FLORA LICHTMAN: When you say fix, you mean grab it?

DEVAKI BHAYA: They grab it and they make it into a form that you can use. You can’t use nitrogen, but if you 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 building blocks for life. So, I mean, that’s the theme. When you have something, you grow. You have excess of it, you store it. And then when hard times come, there it is. Not just for yourself, but possibly for others, which I find remarkable.

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

DEVAKI BHAYA: Absolutely.

FLORA LICHTMAN: They simplify their life a little bit.

DEVAKI BHAYA: 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 figured out this ability to do things, to have this hierarchy of responses.

FLORA LICHTMAN: Which seems very sophisticated for a single-celled organism.

DEVAKI BHAYA: You take the words out of my mouth. I mean, they are beyond sophisticated. It actually makes my– 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.

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, I mean, the acme of sophistication.

FLORA LICHTMAN: Wait, why is that the acme of sophistication?

DEVAKI BHAYA: Yeah. 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. I mean, if we have something happen to our lives, it’s one thing, it kind of takes over. These guys are dealing with this fluctuation, changes.

Let’s give an example of light. Light is changing through the day and night. Suddenly there’s too much light. There’s too little light. The clouds come in. You can’t just sit there and 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. 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.

FLORA LICHTMAN: It is amazing. I mean, when you say it that way, I’m like, wow, I have decision fatigue around what to cook for dinner tonight.

DEVAKI BHAYA: Exactly. And I think that if we were to go down the route of, say, well, how do you microbialize? It’s this idea, I think, of decision-making. And I think if you really go philosophical on anybody, you could say, how many decisions do we make rationally, and how many decisions do we just make? And that, I think, is a big difference.

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. If you muck up, you’re dead.

FLORA LICHTMAN: Yeah. If you muck up, you’re dead. What other lessons do you take away from them?

DEVAKI BHAYA: Good question. I would say, for me, what’s amazing about microbes is how much is going on that, as a society, as human beings, we just totally ignore. I mean, if you shut down microbes tomorrow, we would not be–

FLORA LICHTMAN: Problems.

DEVAKI BHAYA: But, I mean, if you polled the average person, even me, I don’t think I would really say, well, 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.

And I think that’s something that absolutely I would love– I mean, I would love to be 100 years from now because we are still going 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.

FLORA LICHTMAN: Yeah. Yeah. Yeah, where will we be in 100 years?

DEVAKI BHAYA: Where will we be in 100 years?

FLORA LICHTMAN: Thank you so much for joining me today, I really enjoyed it.

DEVAKI BHAYA: Thank you so much, Flora.

FLORA LICHTMAN: Dr. Devaki Bhaya, a molecular microbiologist at Carnegie Science in Stanford, California.

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