TRANSCRIPT The Microbe Revolution

This is a transcript of the Gastropod episode, The Microbe Revolution, first released on Nov. 11, 2014. It is provided as a courtesy and may contain errors.

NICOLA TWILLEY: Hello and welcome to Gastropod! I’m Nicola Twilley—

CYNTHIA GRABER: And I’m Cynthia Graber. And as usual, we’re here to share fascinating tales about the science and history of food. This week, we’re going to spend a lot of time talking about a vegetable called a cassava.

TWILLEY: You may not have heard of it—but according to Bill Gates, it is the world’s most interesting vegetable. He also called it the stud of the vegetable world.

GRABER: The stud?

TWILLEY: Yes. Bold statements indeed. He argues it’s kind of an overlooked secret weapon in feeding the world. So it’s this long, nobbly, starchy tuber—it looks a little bit like a sweet potato shapewise. It has a hard brown outside and a firm, white or yellowy, really like a potato interior. And it’s a staple food for nearly a billion people. In fact, nearly 40 percent of all of the calories consumed in Africa come from the cassava.

GRABER: It grows in the tropics of South America, and Asia, and Africa, and, like Nicky said, it plays a really huge role in the daily diet of the people in those regions, especially the rural poor. And today, you’ll meet the scientists in Switzerland and Colombia who are trying a revolutionary new method to get cassava plants to produce even more food, using less fertilizers and pesticides.

TWILLEY: And you’ll join us for a cassava tasting adventure right here in the U.S.

GRABER: To learn more about growing more cassava, we’re first going to start off with fungus sex.

TWILLEY: Obviously.

GRABER: Bear with me. Fungus sex turns out to be the key to the whole thing.

IAN SANDERS: So I’m Ian Sanders, I’m a professor at the University of Lausanne in Switzerland, and I’ve been there since 2000.

GRABER: Ian is a fungus geneticist. He’s a British scientist who’s now working in Switzerland. He has closely shorn hair, glasses, and a thin gold hoop in one ear.  And he’s been studying a particular type of fungi called mycorrhizal fungi for 26 years.

SANDERS: So here we are in this room, this is where we actually culture the fungi. The fungi we work with are very small microorganisms that live inside the roots of plants.

GRABER: And here’s the thing. For the longest time, people thought that mycorrhizal fungi basically didn’t have sex. Most fungi go through a process where they meet up and fuse and produce new offspring that contain DNA from both parents. But for some reason, scientists had this fixed belief that mycorrhizal fungi didn’t do it—and that instead they just created new copies of each individual by cloning. I’m not sure why they thought mycorrhizal fungi were different, but they did.

TWILLEY: That seems kinda strange to me.

GRABER: It seemed strange to Ian, too. So he set up some mycorrhizal fungi experiments in his lab, and six years ago, he actually caught them at it….

SANDERS: No one had ever actually tested this. You just read again and again in the literature that these fungi grow clonally and vegetatively all the time and they don’t fuse with other individuals. And so we put them together in the lab, and sure enough, they fuse…

TWILLEY: Oh my God. Call the papers. Mycorrhizal fungi caught in illicit sex scandal. So obviously I could listen to you talking about fungus sex all day long. But why are you telling us this? And what does it have to do with cassava?

GRABER: So these fungi help us grow what we eat—including, of course, cassava. Here’s why—these particular fungi have been helping plants out as long as there have been plants on Earth, about 450 million years. And it’s not just any plants—it’s nearly ALL plants, all over the world. They live in and on the roots of about 80 percent of the plants on the planet. Sanders keeps the fungi on clear plastic dishes in this incubation room in his lab in Switzerland. He’s got thousands of samples here stored in small cubes that look like mini refrigerators.

SANDERS: I’m just taking one out now—what they look like, it’s just a plate that has a clear gel on the bottom and it has a top on it, so to keep the whole thing sterile. And in there you can see a mass of roots growing all over the gel. And when you hold this thing up to the light, what you can see is little tiny filaments, like little tiny strands of cotton, coming out from the roots onto the gel, and that’s the fungus.

GRABER: Those strands are called hyphae. They stretch many inches out into the soil around a plant’s root to grab onto nitrogen and phosphorus and even water and then they transport it all back to the plant. The creatures are incredibly important extensions of the root system.

TWILLEY: I see. It’s kind of like how obsessed everyone is these days with the microbes in our gut. And how we have millions and millions of microbes living inside us that are the reason we can even digest certain foods. I mean, we would really have a hard time getting enough vitamin B and K and plenty of other nutrients if we didn’t have these bacteria synthesizing it for us from the food we eat. So plants need their microbes to get all the nutrition they need, just like us.

GRABER: Yeah, it’s similar. There are millions of microbes in and around plant roots in the soil. I should point out—microbes is kind of a catch-all name for one-cell creatures—it includes bacteria, and fungi, and viruses. We’re mainly talking about one type—the mycorrhizal fungi—but for example there are other microbes that help plants, say, get nitrogen, and others that help protect against diseases. In return for all this, the plant feeds the microbes sugar, just like we feed bacteria in our gut the food we eat.

SANDERS: Almost all our food plants naturally have these fungi growing in the roots. So all plants that we use for food—so, if we think of the most important ones, rice, wheat, potatoes, cassava in the tropics—all of these plants naturally form this association with these fungi and have these fungi growing in the roots.

GRABER: And so for thousands of years, basically as long as we’ve been farming, plants and microbes have worked together. The interesting thing is, we didn’t discover microbes in the soil until about a hundred years ago. And we’ve only recently had the scientific tools to really tease out that relationship. We still don’t know how to even grow most of them. That’s how new this science is. Scientists estimate that we can grow maybe one percent of all the different microbes that live in soil. But even though we didn’t know what we were doing, farmers have, again for thousands of years, they’ve rotated crops or grown crops together in certain combinations, and they’ve added compost. We know now that these traditional farming methods help to contribute and support a variety of types of microbes in the soil. And the plants depend on these tiny creatures.

RUSTY RODRIGUEZ: I think what we’ve done over the last hundred years in agriculture, is to try to take microorganisms out of the picture. And by doing that—by disrupting the soil with tillage, by using chemical pesticides—we have greatly altered the agricultural microbiome.

GRABER: That was Rusty Rodriguez, we’ll meet him again later. And he and Ian both agree: the current system of industrial agriculture screws up the soil microbiome.

TWILLEY: OK. And so now what does this have to do with fungi sex?

GRABER: So when Ian saw those fungi exchanging DNA—fungi sex—he had this crazy idea. Breed fungi. Breed new varieties. Basically tell the fungi who to have sex with to breed better fungi. Just like we’ve been doing with plants for thousands of years.

SANDERS: And if you think about it, in agriculture, the majority of food in the world is produced from about three or four plant species, right? And the reason we can get such a high productivity of these small number of plant species is because for millennia, humans have been, without knowing about genetics until recently, have been breeding plants by using natural genetic variation to cross plants, develop new varieties, and increase crop yields. Well, there’s no reason we can’t do that with the mycorrhizal fungus as well… And it’s my belief that if we take the approach that farmers have done for, actually thousands of years, and we apply that in microbiology to the production of mycorrhizal fungi, we can come up with something that’s much better than what we have now.

TWILLEY: Oh, so that’s just like in our last episode, where Michael Mazourek bred that amazingly awesome new squash for chef Dan Barber.

GRABER: Right. Ian wants to be like a plant breeder. He wants to create improved varieties.

TWILLEY: But we’ve had agricultural crops in the fields for thousands of years, so wouldn’t the microbes have evolved to be as useful to the plant as possible?

GRABER: That’s certainly a criticism that Ian sometimes hears. One thing—the way we farm now actually harms microbes in the soil, either by killing them outright or by not plowing crop remains back into the soil as microbe food. So adding microbes to the soil or supporting them could make sense.

TWILLEY: Like probiotics for soil, basically.

GRABER: Right! And in terms of breeding them? Ian basically says—we’ve had such a heavy hand in agriculture for thousands of years, why do we think microbes would have automatically adapted to be optimal?

SANDERS: If you use the argument from these researchers, then no one would have produced any plants through plant breeding, because they would have said, “Well, nature’s already made the best plants, and we can’t make any more that are any better than what nature has made.”

GRABER: So Ian got busy organizing some fungi orgies in the lab. And he bred new varieties of fungi that way. But he needed to test them out on plants. A colleague had a project growing rice in a campus greenhouse. So a few years ago, he tested his theory. He grew rice in the greenhouse with genetically distinct lines of mycorrhizal fungi colonizing the plant roots. Ian didn’t expect much—he hoped some would grow a little better than others. Instead—some types of fungi helped the rice grow fives times as much food.

TWILLEY: Five times! If you’d said double I’d have been blown away, but five times!

SANDERS: So the five—fold growth in rice just by inoculating the rice plants with genetically different fungi—was truly astounding for me…  So it was obvious straight away from this finding that we could potentially use this genetic change in the fungus as a way of actually usefully and practically improving the growth of our food plants in agriculture.

GRABER: One way they could help—they could help the plants produce more food. And here’s another—the fungi could help plants grow larger with significantly less fertilizer.

TWILLEY: That’s a huge issue. Fertilizer washes off of agricultural fields and into rivers. The most dramatic example is that dead zone in the Gulf of Mexico.

GRABER: Right, fertilizer washes of farms all along the Mississippi River and then flows straight out into the gulf.

TWILLEY: And it creates this crazy huge area the size of Connecticut where all the fish are just dead. So if these microbes really can reduce fertilizer use and run-off, that would really make a difference. Especially if they can get higher yields at the same time.

GRABER: That’s what Ian was thinking. But other scientists weren’t so impressed by his results. They said, okay, it worked in the lab. But the soil in the lab was sterile. That’s nothing like the messy and complex environment out on a farm. Ian had people tell him it would never work in the real world.

SANDERS: That’s like a red flag to a bull you see. So I thought well we’ve got to find out whether it works in a real farming situation in the field.

GRABER: But there was another problem. People knew decades ago that mycorrhizal fungi helped farming. And so some companies set up shop in the 1970s to sell the fungi to farmers to add to their fields. But there was no way to grow mycorrhizal fungi except on plant roots in the ground. So the companies were basically selling a whole bunch of soil. It weighed a ton and there was no way to know how much active product any amount of soil had. Those companies failed.

TWILLEY: So how is Ian growing his fungi?

GRABER: Well, a few years ago researchers finally figured out how to grow mycorrhizal fungi on special roots on a petri dish. That’s how Ian grows them in the lab. And then other scientists developed a gel that could keep the fungi alive to be shipped out to farmers in small tubes. It looks like there are a couple of these products out on the market. Ian and his research partner—her name is Alia Rodriguez—they worked with a new company in Spain that makes the gel. It has one type of mycorrhizal fungi in it.

TWILLEY: Just a regular commercial variety, not one of Ian’s special fungus breeds?

GRABER: Yeah, just one that naturally grows in soil that they grow up in the lab. They sell it to farmers. Ian and Alia did partner with them to put their own breeds in, but that wasn’t until later. So anyway, they first tested that Spanish’s company’s product. They wanted to know how big a difference it would make if they added this regular, normal fungi to crop yields. And they did it in the field in Colombia.

GRABER: Here I am in Colombia. When we headed out into the field, it was 5:30am. The sun had barely lifted into the clouds. You could hear choruses of insects, and frogs, and birds hidden in the dense undergrowth. It had rained recently.

ME: Glad we got me boots!

TWILLEY: Why did Ian want to do this experiment in Colombia?

GRABER: Honestly, the real reason is that he already knew Alia Rodriguez. She’s an agronomist and she’s based in Colombia. They’d met when she was also studying mycorrhizal fungi in Europe. Ian’s at home in the lab, but he’ll be the first to admit he knew nothing about farming. Alia’s an expert in setting up farm experiments.

ALIA RODRIGUEZ: I cannot say that my family we are, you know, farmers, but I think that in Colombia, it’s quite easy to be related to the field and to the producers and the farmers, because we, you know, everywhere we see people dealing with cropping and producing food.

GRABER: But in a nice twist, Colombia was actually a great choice. It’s the native home of cassava. And as we already discussed, cassava is this starchy root. It’s an incredibly important food all over South America and Asia and Africa. So if they could help cassava grow more food, then Ian and Alia could help people—people who really need it—they could grow and eat more food. They set up their experiments out in fields owned by an agricultural college called Utopía, or, appropriately, Utopia. The students and professors help out.



ALIA RODRIGUEZ (IN FIELD): Have you ever seen them before? I’ve never seen them!

GRABER: We were checking out some peanuts growing on their farm there—you might also hear the rain. It was raining again. So—first they did a test study. They took the gel—it’s a clear gel, but you can see these whispery thin strands of hyphae throughout the tube—they applied a thick layer of the gel to sticks from the cassava plant, and they buried the sticks in the soil. When the roots grew, they grew down through the gel with the mycorrhizal fungi. At the end of the experiment, the plants with the fungi grew up to 20 percent more cassava roots. Nicky, remember how I said that fungi might be able to help reduce the amount of fertilizer farmers would need?


GRABER: So that was also a dramatic difference there. Not only did the plants grow 20 percent more roots—and that’s a huge improvement—they could do it with significantly less fertilizer.

SANDERS: Well, we were absolutely delighted, I mean…this sort of surprised me. I expected an effect that would be smaller than that, to be honest.

GRABER: Nice, right?

TWILLEY: Sounds pretty good to me.

GRABER: But what Ian really wanted to know is whether his lab-bred genetically different fungi can help plants even more. That is, can he take the tradition of plant breeding and apply it to create even better fungi? He bred 15 new varieties, and the Spanish company grew each one up separately in the gel.

SANDERS and ALIA RODRIGUEZ: And this is cassava! Small ones, very small ones.

GRABER: There were two experiments in the ground on that hot day that we traipsed around the fields.

SANDERS: This is disappointing in the sense that they were planted in the bags when there was a very strong drought, and they don’t like growing in bags.

GRABER: The team first tried planting the cassava in plastic bags to keep one fungus from reaching over to a nearby plant. But they didn’t do so well. Some look a little sickly. We headed over to another plot. In that experiment, they planted the cassava directly in the ground. These all looked uniformly fantastic. The broad emerald leaves were glistening with rain, and the students tramped around and took a bunch of measurements. Later that evening, Alia and Ian and I pulled up some chairs to chat.

ALIA RODRIGUEZ: For me it was like a good surprise to see the experiments, you know, running in the field now. It’s been a sort of, quite a process to get the things going on here… And finally to see that it’s happening, you know—it’s difficult but it’s happening, it’s achievable. So it feels good, it feels nice to see that, and the theme of the students working and, you know, it’s quite a good feeling. Yeah.

GRABER: It takes almost a full year for cassava to reach maturity. So for each new study, they’ve had to wait almost a full year for the results. The first study, the one in the plastic bags, that was scheduled to be harvested a few months after I left Colombia.

SANDERS: We have these experiments set up in the field now and we honestly have no idea what’s going to happen. I mean, of course, that’s why we do the experiment, because we don’t know what’s going to happen. And, yeah, it’s a pretty nervous time. I mean, one of the experiments we’ve been running now for 8 months, so we know that in 11 months we’re going to harvest, and, you know, we might not see much before that harvest. And it is a bit worrying, you know, because these are long-term experiments. Eleven months is quite a long time to wait.

TWILLEY: That is a long time. And this is one of the challenges with farming research. It takes a long time to grow plants and figure out if what you’re testing has had an impact.

GRABER: Right. And there’s another challenge—farming is messy! You don’t have control of everything like you do in the lab.

TWILLEY: Things can go wrong out there in the real world. Like those plastic bags to keep the fungi separate—that didn’t work out so well.

GRABER: The plastic bag disaster? That was nothing compared to what happened next. I left the area, and then a few days later, Ian and Alia and the postdoc named Isabel Ceballos, they all left too. And then a few days after that, it stormed. I mean stormed. A month’s worth of rain washed down in only a couple of days. The entire area was flooded.

TWILLEY: Oh shit. They must have been totally freaking out.

GRABER: They were. They couldn’t back into the fields, and the students at the university were sending emails back saying it looked like all the plants had drowned. I called Isabel to ask her about it—she’s the one who first found out about it when a student emailed her. She said she almost went crazy. If all the plants had drowned, they’d have lost an entire year’s worth of research. And they only had funding through the following summer. So basically the entire project could have gone down the tubes.


GRABER: They’d have been screwed. And now, dear listeners, we’re going to keep you hanging for a little while. This is what we call dramatic tension.

TWILLEY: So, while Ian and Alia and you and I and our listeners all wait on the edge of our seats to hear what happened to their cassava plants, I want us to get a little better acquainted with the cassava itself. You may remember me saying that Bill Gates called it the most interesting vegetable in the world. And a big part of what makes it so interesting, at least to Bill Gates, is that it feeds so many people, in areas of the world where hunger is still a really big issue. And it has other special qualities. It’s super low maintenance: it grows in bad soils, it’s resistant to a lot of pests because most varieties have a low level of cyanide in them.

GRABER: That’s, of course, removed before we eat it.

TWILLEY: And it tolerates heat and drought well. Altogether, very easy going. Not to mention well-equipped to handle climate change. So we may all be eating a lot more of it in the future. But here’s the thing. Although it feeds billions of people around the world, it’s not super familiar to most Americans. Cynthia, when you told me this story was about cassava, I was like, what’s that when it’s at home?

GRABER: You may have heard of it under different names. It has a bunch of different aliases. I am going to take you on a cassava crawl.


GRABER: We’ll check out restaurants in Cambridge and Somerville—I bet we can find plenty of cassava within a couple of miles of my apartment. Let’s start at Machu Picchu. It’s a Peruvian restaurant down the block.

RESTAURANT SERVER: Are you ready to order?

GRABER: Yes! We’d like the yuquitas a la huancaina.


TWILLEY: And then we’re also going to get some boiled yucca.

GRABER: I think I liked fried yucca better than fried potato.


GRABER: I know. Okay, we have tried fried yucca and now we have some boiled yucca.

TWILLEY: Yep, here we go. It’s still pretty good, actually!

GRABER: It is, I still like it.

TWILLEY: Okay, so we went to a Peruvian place, we ate a bunch of yucca, and now we are at Muqueca, which is a Brazilian restaurant.

GRABER: Heading in to try some more cassava.

TWILLEY: Okay so let’s order. We are going to get the mussels soup with the yucca base please.

GRABER: And the—how do you pronounce that?


GRABER: It comes with farofa, right?


TWILLEY: It’s the national dish of Brazil, I’m can’t pronounce it—I’m not going to massacre it again—but it has red beans, it has plantain, it has various greens and onions and things like that, but it also has this like beige powdery stuff mixed in, and I think that is our friend the cassava.

GRABER: It is! In Portuguese it’s farofa. It’s a powdery yucca, powdery cassava, that’s cooked up with a bunch of spices, and we actually have a little side of it here.

TWILLEY: Which is bright yellow!

GRABER: Yeah, this is without all the spices. So we can taste it on its own.

TWILLEY: It’s like a crunchy powder with a nice savory, sort of salty, flavor. It’s funny—it just adds a sort-of gritty, crunchy texture. Gritty sounds bad but it’s actually good. Like sesame seeds, adding little, tiny crunches in every bite.

TWILLEY: Okay so we’re outside Dado and looking at the bubble tea menu. Lots of flavors: English breakfast, green tea latte,

GRABER: Oh, I just noticed the green tea latte!

TWILLEY: Mint matte, peach blossom… Okay, so one—what did we end up deciding? One green tea, one bubble tea.

GRABER: I love how chewy they are.

TWILLEY: My turn.

GRABER (trying to extract the last bubbles from the bottom of the cup): Last bubbles!

TWILLEY: Go, Cynthia!

GRABER: They’re not coming out. (Laugh) They’re stuck in the straw, but I want to get these last cassava bubbles!

TWILLEY: I don’t want to say suck harder on tape, but I need to say it.

GRABER: I got it!

TWILLEY: So, yuca fries, crunchy farofa topping, and the tapioca pearls in bubble tea are all the same thing: cassava. With that many aliases, it really is kind of the secret superhero of the crop world. And it’s rather tasty too, I have to say. But I think we’ve left our listeners hanging on for long enough. Time to get back to those poor researchers in Colombia and their drowned plants.

GRABER: Yeah, Isabel was really freaking out. Ian and Alia were obviously super worried, too. It took three full days before the local students could even get out onto the fields to find out what happened.


GRABER: In an amazing stroke of luck, the only plants that died were the border plants—those are the ones that didn’t have an extra application of fungi to the roots. Nearly all the plants that had the special fungi, they survived.

TWILLEY: So the research was safe. Nice!

GRABER: Seriously.

TWILLEY: And now—the final results?

GRABER: Right. The last bit of suspense. Last fall, Isabel went down to harvest the first cassava experiment. This is the one where the plants had been planted in plastic bags, and they looked a little weak. One by one, Isabel and the local students slashed through the bags. They hacked away at the roots and brushed away the dirt to uncover all the purplish cassava roots. Isabel weighed all the results and brought the best samples back to Bogotá for testing. In the spring, she went back and did the same thing with test two. So recently I called up Ian and Alia to hear what they found out—they happened to be together in Switzerland. They were delighted to see that some varieties of mycorrhizal fungi made plants grow dramatically more roots than others. And what was the most interesting and exciting to them is that it was the same in both experiments.

SANDERS: If a fungus made cassava grow particularly well in the first year of the experiment, it also made cassava grow very well in the second year, the second experiment.

ALIA RODRIGUEZ: It’s very, very interesting, very exciting for us, because we can see that it’s a real effect. It’s reproducible, it’s a stable effect. It’s not something random that one season one fungus made the plant grow better, and the next season did the opposite or something like that. They are very consistent results. It’s very, very happy news for us.

SANDERS: So I was not really expecting necessarily to get the same sort of result, but actually the results are remarkably similar between the two experiments.

GRABER: So that should have made you feel pretty good, no?

SANDERS: Yes, very good and very surprised! It really looks like it’s working, it’s working better than we expected. I have to say, the differences in the size of cassava roots according to which fungus has been used are really huge, they’re several fold differences. Which is also not something I would really have expected. You have to remember, this is just by breeding the fungi—so modifying, if you like, the genetics of the fungi through breeding. And I’m really surprised that that can have such a large effect on the plants.

GRABER: Even though you saw a five-fold different effect on the rice?

SANDERS: Yeah, but the greenhouse situation is so unreal, you know, so out of touch with reality. I just didn’t think we’d see such large differences in the field.

GRABER: Is it the same? It’s not like a five-fold difference like in the greenhouse?

SANDERS: It’s about three to four.


SANDERS: Three- to four-fold difference. It’s pretty large. Not in the size of the whole plants, but in the size of the roots, in this case it’s the roots we’re the most interested in. So yes, we were very surprised. And actually I was just showing these results yesterday to an agronomy professor from Zurich, and he was completely shocked when he saw the results. Because plant breeders, if they were breeding cassava, they wouldn’t see this sort of variation in cassava growth after one generation of breeding new plants. So actually it seems to be a particularly powerful way of changing how large cassava can grow.

GRABER: He’s shown that he can breed fungi and grow more food.

TWILLEY: But Ian’s not the only one working on microbes for agriculture. This is super cool research, but there are companies who already sell products for agriculture based on microbes.

GRABER: There are. There are some that have been in use for a few decades now—they primarily use a bacteria that helps soy plants and other legumes. But more are coming. I spoke to dozens of people when I was researching this story—dozens of scientists and companies. One company named Marrone BioInnovations is headed by a woman named Pam Marrone. She’s a real leader in the field. They have a number of products already on the market that are based on microbes. One is a pesticide that comes from a soil bacterium, and it helps protect plants from sucking insects. And then I also met this guy—Rusty Rodriguez. We heard from him at the beginning. He’s in Seattle.

RUSTY RODRIGUEZ: So these are actually the university greenhouses and we rent space here. We’ve got five different benches…

GRABER: He’s a microbiologist and he’s head of a company called Adaptive Symbiotic Technologies. His company—he founded it with his wife Regina Redman—it’s cultivating different species of fungi. Some of them grow in plant leaves, others in other parts of the plants. This all started because he was a microbiologist and he was studying plants that grew in high-stress soils. So he and a team checked out plants in the geothermal springs in Yellowstone.

RUSTY RODRIGUEZ: In Yellowstone, there are geothermal soils, and they get up to about 65C in the summer.

TWILLEY: I come from a world where we measure temperatures in Celsius, and that is rather warm.

GRABER: About 149 degrees Fahrenheit.

RUSTY RODRIGUEZ: And they drop to about 20C in the winter, but they don’t freeze. And there’s a small group of plant species that live in those habitats, maybe 12 different species or so. We focused on one that grew in the hottest soils, and it grew isolated in those hot soils from the other plant species. Well, while we were doing our studies, what we found was that all the plants that we pulled and looked at were all colonized by one fungal endophyte that was living inside of it.

GRABER: An endophyte is a fungus that lives in plant leaves. So this inspired him to try colonizing other plants with those fungi.

RUSTY RODRIGUEZ: And we found that we could move these fungi from the native plants into these agricultural crops. So for example we could take the fungus out of Yellowstone plants and we could move those into watermelon or tomato. And when we did that, the plants got colonized and became heat tolerant.

GRABER: Now they have people collecting plants from extreme environments all over the U.S. They figure out what fungi help the plants survive. Then they try to isolate ones that would be helpful for agriculture. The fungi he’s been developing help plants survive droughts and floods and heat and cold. He grows them up in the lab and greenhouse. And he’s already testing them on farms in 18 states.

RUSTY RODRIGUEZ: Well, the US market is huge. And the efficacy of many chemicals is beginning to wane. I think that biologics are the next paradigm for agriculture.

GRABER: He has a new product on the market this fall called BioEnsure. So here are some results from his products: there was a drought in the Midwest in 2012, and farms that were treated with BioEnsure—they had an 85 percent higher yield than ones that weren’t treated with the fungi. For a normal year, no drought, the yield might be 20 percent higher.

TWILLEY: Wow—those numbers are super impressive.

GRABER: Yeah, and they’ve also started testing in India and Latin America. Now, Marone BioInnovations and AST are pretty small companies—but this approach is catching on with huge seed and agriculture companies, too. Bayer bought a small biopesticide company. The huge company Syngenta bought another one. Monsanto is even in on the act—last fall they paid a Danish company 300 million dollars to form a partnership called the BioAg Alliance. It’s to develop what they call “microbial yield and fertilizer enhancers.”

TWILLEY: Basically, microbes are really hot right now. There was even a report out last year called How Microbes Will Help Feed The World. It came out of a two-day meeting in Washington, DC.

GRABER: Right. Ian was one of the chairs of that meeting, and Rusty was involved, too.

TWILLEY: You hear about the Green Revolution in the 60s, when new agricultural technology and huge advances in crop breeding raised yields exponentially. And I feel like we’re right at the start of the microbe revolution right now.

GRABER: It does seem like it.

TWILLEY: So, not to rain on anybody’s parade, but I do want to ask you something.

TWILLEY: So first of all, is anyone concerned about new breeds of microbes being let loose in the field? About maybe some unforeseen consequences of letting them out in the environment?

GRABER: Yeah, they are. First, I do want to say that there are already many different varieties of these mycorrhizal fungi naturally in the field. And Ian and Alia do have students studying how the addition of these fungi affects communities of microbes in the soil. And the companies that are already selling microbial products—those are based on ones that already exist in nature—so, they have to go through plenty of stringent hoops. They have to do studies to make sure that the products won’t hurt plants or animals or the environment.

TWILLEY: OK. The other thing I’m worried about is about this idea of a Microbe Revolution in agriculture. Because the Green Revolution in the 60s was great in some ways, and not so great in others. On the one hand, you often hear that it saved a billion lives from hunger. India, in particular, went from regular famines to be a net exporter of food. But there were real problems, too. Traditional farming methods around the world—methods that were much more sustainable in terms of water and soil and biodiversity—they were replaced with this intensive, industrial agriculture. Which means monocultures of wheat, corn, or rice. It means depleted soil and groundwater reserves. And it means the kinds of fertilizer run-off and dead zones that we talked about before. And all of that equipment and pesticides and fertilizers that you need for this industrial method of agriculture—that’s expensive!

GRABER: Not to mention the seeds. That’s one of the thing that ended up being a huge downside of the Green Revolution: these new breeds had much higher yields, but they were also hybrids. That meant that farmers couldn’t save their own seeds. Instead they had to buy new ones—from big companies like Monsanto and Cargill—they had to buy them every single year. Monsanto is already getting into the microbe revolution, and they’re a big company with shareholders. Their mission is to make money, not to feed the world.

TWILLEY: It’s actually easy to imagine how—just like these hybrid seeds developed in the 1960s were patented and had to be bought new each year—it’s easy to see how Ian’s special microbes could be licensed to a company that owns the IP and charges farmers to use them.

GRABER: Everything does cost money. So that will probably happen. The question is always—how much will it cost, and how much will it help? Especially for the people who need it the most.

TWILLEY: And that’s another issue. Just growing more food doesn’t necessarily get rid of hunger. Food doesn’t get to the people that need it, there’s massive food waste—these are issues that simply increasing crop yields doesn’t address. As we know from the Green Revolution.

GRABER: Right. I do want to say that the people I spoke to—people with small companies, like Rusty—they’re committed to making sure that their products are helpful to people in poor communities. Obviously that’s the main focus for Ian and Alia as researchers. But of course at the beginning of the Green Revolution, everything looked rosy then, too. It does seem like both organic farmers and conventional farmers are excited about the potential for microbes to help farming. No matter what, you’ll definitely be hearing more about this. Microbes in agriculture—that is going to be huge.

TWILLEY: That’s it for this episode of Gastropod!

GRABER: We hope you enjoyed exploring the wilds of Colombia with us.

TWILLEY: In a month, we’ll take you to the distant land of—Connecticut.

MAN: I never ate kelp before in my life until this year, and I absolutely love it now.

GRABER: You’ll hear about the history of kelp farming, and why you may soon be seeing more seaweed on your plate.

TWILLEY: But first, we’ll be back in two weeks with one of our bite-sized episodes to keep you going. So, remember last month we said we’d give away a signed copy of Dan Barber’s book, The Third Plate, to one of our listeners? We got so many lovely emails from you about that.

GRABER: We have the best listeners.

TWILLEY: And the lucky winner was Adrian Down, who, speaking of lovely listeners who are talented and smart,  actually has degrees in maths and physics and spent a year farming in Hawaii. Adrian also sent us a funny story in his email—he was an undergrad at Berkeley, and he said he remembers that, back in 2003, Berkeley had just hired a wacky writer named Michael Pollan.

GRABER: That is a fortuitous transition, because—for this episode—I actually have to thank Michael Pollan and Malia Wollan at the UC Berkeley Food and Farming fellowship. That funding got me down to Colombia to report this story.

TWILLEY: Thanks also to Ian Sanders and Alia Rodriguez, who let you tag along in the field with them.

GRABER: And to Rusty Rodriguez. And to all of the literally dozens of scientists who let me spend hours on the phone with them asking them every question I could think of about microbes and agriculture.

TWILLEY: By the way, you can, and you really should, read the story Cynthia wrote about this for NovaNext—we have a link to it on the website, and it’s packed with extra details and even more background on the science and history.

GRABER: Finally, thanks to Anna Wexler—who by the way, has a really great film out called Unorthodox. Anna and Jonathan Reisman, and Tim Buntel joined us for a listening party and offered all kinds of helpful editing suggestions.

TWILLEY: As usual, check us out online at, where we’ve posted all kinds of links, photos, and extra information. While you’re there, sign up for our email list to get new episode alerts. And please feel free to like us on Facebook,  follow us on Twitter at gastropodcast, and email us at [email protected] As you can probably tell by now, hearing from you guys is our favorite thing.

GRABER: You can also subscribe on iTunes or on your favorite podcasting app. And If you like us, let them know on iTunes by rating the Gastropod podcast. That helps get the podcast in front of new listeners.

TWILLEY: And, of course, tell your friends about us.

GRABER: And thank you for listening!

TWILLEY: Till next time.