Environment
2:33 am
Fri June 28, 2013

Put Down Oil Drill, Pick Up The Test Tube: Making Fuel From Yeast

Originally published on Fri June 28, 2013 8:41 pm

What if we could get our gasoline, diesel fuel and jet fuel from yeast instead of from oil wells? That's not as crazy as it sounds. In fact, it's already happening on a small scale. And there's a vigorous research effort to ramp this up on a massive scale.

One of the more innovative approaches uses a new technology called "synthetic biology." Jay Keasling is one of the leaders in this hot field.

With his supershort crew cut and friendly demeanor, Keasling would fit in nicely where he grew up — on a corn farm in Nebraska that's been in his family for generations. But these days you'll find him in a glistening building in Emeryville, Calif., home to several of his many endeavors.

Among the many hats Keasling wears is that of associate laboratory director for biosciences at the Lawrence Berkeley National Laboratory. He's also CEO of the Joint BioEnergy Institute, director of the Synthetic Biology Research Center, and a professor at the University of California, Berkeley.

Not to mention founder of three biotechnology companies — Amyris, LS9 and Lygos.

"My research [focus], since I've been at Berkeley for the past 20 years, is, 'How do you engineer chemistry within cells?' " Keasling says. "I really believe you can use microbes as little chemical factories to produce almost anything we want."

This is the basis of synthetic biology — genetic engineering taken to a whole new level. Instead of tweaking one or two genes, Keasling and his colleagues change a bunch of genes, so microbes such as yeast can be transformed into chemical factories.

His most successful project to date doesn't have to do with energy. Keasling and his team inserted or tweaked a dozen genes in yeast cells and turned them into tiny factories that churn out a partially synthetic version of artemisinin, a key drug in the leading treatment of malaria. (The usual source of artemisinin is a tree known as sweet wormwood, and there are not enough to meet the global demand.)

Keasling's group licensed the synthetic version to a drug company called Sanofi, which has since produced 35 tons of artemisinin, enough for 70 million people. And this spring, the World Health Organization approved the new version as a malaria treatment.

Surprisingly, it's not such a leap from making the artemisinin to churning out fuels. The drug and diesel are both basically hydrocarbons — hydrogen and carbon atoms cobbled together. So Keasling remembers thinking, "if we can just make a few more tweaks to that yeast that produces artemisinin, we can get it to spit out diesel fuels, or maybe even jet fuels, or gasoline."

Sure enough, they made those tweaks.

And now Amyris, one of the companies Keasling founded, "has a factory in Brazil that's using the engineered yeast, taking in sugar and spitting out a product that's a diesel fuel," Keasling says. Already, that diesel is in buses in Rio and Sao Paulo.

There is, of course, a catch: "This diesel is still more expensive than petroleum-based diesel by quite a long shot."

The yeast produces a hydrocarbon called farnesene, which can not only be converted to diesel but also turned into other much more lucrative chemicals. That's how Amyris can afford to make this pricey fuel.

The challenge now is to drive down the price. One way Keasling can do that is to make yeast much more efficient at churning out fuel molecules. Another way to make the end product cheaper is to start with a plentiful, less expensive starting material — raw plant matter instead of purified sugar.

"It turns out that all plants are roughly two-thirds sugar," Keasling explains. It's tied up in a molecule called cellulose."

Lots of biotechnology companies have been working on the problem of breaking down cellulose with some modest success. Synthetic biology could possibly crack it wide open.

Under ideal circumstances, there's enough raw plant material — especially agricultural waste — to supply about a third of the liquid fuel we use. (Though there are potential pitfalls when you grow crops for fuel instead of food.)

These cleaner fuels would help reduce the buildup of carbon dioxide in the air, at least a bit. But ultimately, the challenge of reducing global emissions has to be met on many fronts, researchers say.

"In terms of technology the big lever is to improve the efficiency of the vehicles," says Doug Chapin, director of MPR Associates, an engineering firm in Alexandria, Va. Chapin was chairman of a recent report by the National Research Council, which looked at what it would take to reduce vehicle emissions by 80 percent by midcentury.

"The other big lever is [that] none of this happens unless the nation has the will to decide that this is the thing they want to achieve, almost more importantly than anything else," Chapin says.

Americans and others would need to accept fuels that cost more at the pump in exchange for the much less tangible benefit of a healthier planet. And governments would have to institute that not very popular idea.

Of course, making biofuels cheaper would make that sort of transformation an easier proposition, and that's what drives Keasling.

"There are some huge challenges, but there are huge opportunities," he says. "Imagine if we replaced a third of our transportation fuels and made them renewable. And maybe through other means we could decrease the use of petroleum-based fuels so we were putting much less carbon into the atmosphere. That would be a huge benefit."

Of course, it's intellectually stimulating to figure out how to engineer microbes to do your bidding. But it's also gratifying to feel like you're solving a problem that will help humanity. And Keasling says there's a personal bonus in this for him, too. His father in Nebraska now grows corn for ethanol, which is a very inefficient way to make fuel from crops. Maybe someday he'll be able to switch to a better crop for biofuel.

Copyright 2013 NPR. To see more, visit http://www.npr.org/.

Transcript

RENEE MONTAGNE, HOST:

Yesterday on this program, we heard about a scientist who's trying to capture carbon dioxide from the air. He wants to turn the carbon into energy.

DAVID GREENE, HOST:

And doing that on a grand scale could help slow the pace of global warming because it would simply be recycling existing carbon dioxide instead of adding more.

MONTAGNE: Today, we'll hear about another innovation aimed at slowing climate change. NPR's Richard Harris caught up with a scientist who's using a powerful technology called synthetic biology, which uses yeast to produce a cleaner form of fuel.

RICHARD HARRIS, BYLINE: With is super-short crew cut and friendly demeanor, Jay Keasling could fit in nicely where he grew up - on a corn farm in Nebraska that's been in his family for generations. But these days, you'll find him in a glistening building in Emeryville, California. And among the many hats he wears is that of a high official at the Lawrence Berkeley National Lab.

JAY KEASLING: I'm associate laboratory director for biosciences, CEO of the Joint BioEnergy Institute, director of the Synthetic Biology Engineering Research Center, oh, and a professor at the University of California, Berkeley.

HARRIS: Not to mention founder of three biotechnology companies.

KEASLING: Well, there's Amyris downstairs, LS9 across the Bay, which also works on biofuels, and then a little startup called Lygos just down the street.

HARRIS: Keasling is one of the central characters in a hot, hot field. The 150 engineers, scientists and technicians here at the Joint BioEnergy Institute are pioneering a technology called synthetic biology. It's genetic engineering taken to a whole new level.

KEASLING: My research since I've been at Berkeley for the last 20 years has been focused on how do you engineer chemistry inside cells? I really believe that you can use microbes as little chemical factories to produce almost anything we want.

HARRIS: Keasling's most successful project to date doesn't have to do with energy. Scientists inserted or tweaked a dozen genes in yeast and turned it into a tiny factory that churns out a synthetic version of a key anti-malarial drug called artemisinin. They licensed that drug to a company called Sanofi.

KEASLING: And Sanofi is now producing a product. In fact, they've produced 35 tons, which is enough for 70 million people. And then the drug will go out to people in the developing world.

HARRIS: You'd think that it would be a huge leap from producing a drug to churning out fuel, but Keasling says actually no. Artemisinin is made up mostly of hydrogen and carbon atoms strung together. It's a hydrocarbon, not so different from diesel fuel. So, they realized this could be an important stepping stone on their quest to come up with a biological fuel.

KEASLING: If we can just make a few more tweaks to that yeast that produces artemisinin, we can get it to spit out diesel fuels, or maybe even jet fuels, or gasoline.

HARRIS: Sure enough, they made those tweaks. Keasling's company, Amyris, scaled it up big-time in Brazil where sugar from sugar cane is cheap.

KEASLING: So, Amyris has a factory in Brazil that's using the engineered yeast, taking in sugar and spitting out a product that's a diesel fuel. And diesel is in buses in Rio and Sao Paulo.

HARRIS: And how much does this diesel cost in Brazil?

KEASLING: Well, this diesel is still more expensive than petroleum-based diesel by quite a long shot.

HARRIS: The yeast produces a hydrocarbon called farnesene, which can not only be converted to diesel but also turned into other much more lucrative chemicals. So, now this is a matter of engineering. How do you drive down the price? One way is to work on a cheaper and more abundant starting material: raw plant matter instead of purified sugar.

KEASLING: It turns out that all plants are roughly two-thirds sugar. It's tied up in a molecule called cellulose.

HARRIS: So, one challenge is to engineer organisms that can break down cellulose to liberate all that sugar. Under ideal circumstances, there's enough of this raw plant material - especially agricultural waste - to supply up to one-third of the liquid fuels we use. That would help reduce the buildup of carbon dioxide in the air, at least a bit. Doug Chapin says if you want to cut back on global emissions, those cleaner fuels will help but they won't do it all.

DOUG CHAPIN: In terms of technology, the big lever is to improve the efficiency of the vehicles.

HARRIS: That's the conclusions of a recent report by the National Research Council. Chapin headed that committee.

CHAPIN: The other big lever is that none of this happens unless the nation has the will to decide that this is the thing they want to achieve almost more importantly than anything else.

HARRIS: We would need to accept fuels that cost more at the pump in exchange for the much less tangible benefit of a healthier planet. Of course, making biofuels cheaper would make that an easier proposition, and that's what drives Jay Keasling.

KEASLING: There are some huge challenges, but there are huge opportunities. Imagine if we replaced a third of our transportation fuels and made them renewable. And maybe through other means we could decrease the use of petroleum-based fuels so that we were putting much less carbon into the atmosphere. That would be a huge benefit.

HARRIS: So, how much of this for you is driven by concern about climate change and how much of this is just a natural evolution of a very cool technology?

KEASLING: I think it's both.

HARRIS: Keasling says there's a personal bonus in this, too. His dad in Nebraska now grows corn for ethanol, which is a very inefficient way to make fuel from crops. Maybe someday he can to switch to a better crop for biofuel. Richard Harris, NPR News. Transcript provided by NPR, Copyright NPR.