Engineering Biology for Drugs and Fuels
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engineering biology |
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them. They turn out to have very high energy, about the same energy as gasoline. They’re ideal for the next generation of engine that’s going to come out. It’s a hybrid between a gasoline and a diesel engine that burns very efficiently. They have very high octane numbers.
These are biodiesel replacements that could be put directly into a diesel engine. What’s more, we’re going to need jet fuels. And we need to produce molecules that look exactly like the molecules in jet fuel, because every time you change a jet fuel you have to test it in every engine on every plane, every type of plane.
So, what about this microbe that we’ve engineered to produce an anti-malarial drug? It turns out that the anti-malarial drug is a hydrocarbon. It’s a little bit heavier in molecular weight than diesel fuel and jet fuel. But we can simply knock out the genes that we put in to produce amorphadiene (a precursor to that anti-malarial drug) and now put in genes specific for producing some of these interesting jet fuels and diesel fuels and biogasolines. That’s what we’re doing right now.
What’s more, you can actually engineer the microbe to secrete those fuels so that they separate (fig. 10). This is a test tube; it’s actually a centrifuge tube; this is the fermentation broth, and floating on top is the biodiesel that the microbe has produced and secreted directly.
Now the beauty of this system is that if you take your fermentation tank and shut off the power that stirs the microbes, the fuel will float to the top, the microbes will float to the bottom, and you take the fuel off the top and put it into your gas tank. And this is what companies like Amyris are doing right now. They’ve actually engineered microbes to produce diesel fuel that you can put directly into your diesel tank—no distillation and no further purification. It goes directly into your tank. This will reduce the cost substantially and it means that we can have fuels that will be carbon-neutral and have high energy content.
Figure 10. Centrifuge tube containing fermentation broth with biodiesel floating on top
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jay d. keasling |
With that I’d like to thank the people in my laboratory who did a lot of this work; the people at Amyris who have been working very hard on optimizing these organisms; the folks at the Joint Genome Institute who did a great deal of sequencing to help us discover the genes; and of course our funding sources, in particular, the Department of Energy, which is funding the work on the biofuels, and the Bill & Melinda Gates Foundation for their work on the anti-malarial drug, and I’d like to thank you for your time and attention.