Thank Me Later: New Planet-Saving Bacteria Eats Switchgrass, Makes Biofuel

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People keep saying the biofuel market isn’t going anywhere, but the folks at Lawrence Berkeley National Laboratory have a new trick up their sleeves. They have developed a new super-hardy strain of the bacteria E. coli, and they have demonstrated that it can make a critical biofuel precursor from switchgrass using a simple, low cost “one-pot” process.

Yes, switchgrass. Some of you may recall the snickering among pundits back in 2006, when then-President George Bush used his State of the Union address to advocate for switchgrass as a biofuel crop, but in the past ten years the hardy, drought-tolerant weed has become the focus of intense biofuel research.

E. Coli, Switchgrass, And Biofuel Whack-a-Mole

As illustrated by the chart above, there are several methods for producing biofuel from plants. One of them is a biological process based on the byproducts that emerge when bacteria digest organic material.

E. coli is short for Escherichia coli, a bacteria that lives in the intestines of humans and other mammals. Some strains can make you very sick, but most are harmless, and researchers have been harnessing other strains for use in biological biofuel production. That includes combining E. coli DNA with other bacteria, as well as developing new strains.

The new Berkeley Lab biofuel study involves a new strain of E. coli engineered to overcome a problem that arose after researchers developed a new solution for another biofuel production problem.

The initial problem was that in conventional biological biofuel production, various steps take place in different stages and in different “pots.” Starting with a step that breaks the complex plant structure down into separate bits, the whole process is cumbersome and expensive.

The solution was to develop a “one-pot” method that uses ionic liquids (that’s fancyspeak for liquid salts) to break plants up into cellulose, hemicellulose and lignin. The one-pot ionic method also has the advantage of requiring less energy, since it can take place at room temperature.

However, in a classic case of whack-a-mole, the ionic method created a new problem. The salts interfered with the rest of the process unless they were washed off. That added a cumbersome, expensive step back into the whole process.

The new Berkeley Lab biofuel study builds on earlier research projects that solved one part of the problem by creating a new suite of salt-tolerant enzymes.

The enzymes are used to push plant sugars out so the bacteria can get to them, so the next step was to develop a new strain of salt tolerant E. coli. Earlier studies had nailed a mutation on the gene rcdA that could play a key role, and when the research team tested the new strain on switchgrass, they were right on the money.

Here’s lead author Marijke Frederix enthusing over the new strain:

Armed with the rcdA variant, we were able to engineer a strain of E. coli that could not only tolerate ionic liquid, but that could also produce ionic-liquid-tolerant enzymes that chew up the cellulose, make sugars, eat it and make biofuels.

In case you’re still wondering why the team focused like a laser on E. coli, Frederix also noted that “E. coli remains the workhorse microbial host in synthetic biology.” If you check out the CleanTechnica E. coli archive, you can see some other clean tech applications for bacteria, including sustainable inks, carbon reclamation and conversion, natural herbicides, and self-assembling electronics.

As for switchgrass, it grows almost anywhere in the US, and in some regions it thrives so fabulously that it is labeled as an invasive species.

Jet Biofuel From Switchgrass

So far the team has used its new one-pot method to produce d-limonene, which is a jet fuel precursor. The end goal is to create a low cost, one-pot process that will squirt out jet fuel as a final product.

Whenever they’re ready, the Department of Defense is lined up and waiting. Despite the efforts by Koch-linked legislators to kill off DoD’s biofuel program, the agency is committed to a carbon neutral fuel source that provides the US with more strategic flexibility when it comes to picking global allies.

The global commercial airline industry is also fully committed to biofuel as the only viable path for future growth in a low carbon economy.

Take a look at the companies displayed in the chart below, and you’ll see why the Koch brothers  — who have been pushing back against biofuels in order to protect the interests of their family business, Koch Industries — are up against a lot of firepower in the emerging biofuel market:

The push for a future biofuel market is also strong in other oil-producing nations. One interesting example is a jet biofuel demonstration site in the United Arab Emirates, at Abu Dhabi’s Masdar City.

The demo project is designed to shake out a combined food and biofuel system that will deploy salt-tolerant plants, enabling the whole process to run on seawater without the need for an expensive desalination step.

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Image cropped): via Berkeley Lab.