Published on July 3rd, 2013 | by Tina Casey0
Harvard U. Researchers Transform Bacteria Into A Biofuel Powerhouse
July 3rd, 2013 by Tina Casey
A research team from Harvard University’s Wyss Institute for Biologically Inspired Engineering together and Harvard Medical School is on track to transform the common bacteria E. coli into a jack-of-all-trades producer of biofuels, pharmaceuticals, plastics and just about anything else that is presently made from petroleum precursors. The trick is to get E. coli to generate the same raw material present in petroleum, and to do it on a ramped-up scale that lends itself to commercial development. So, how’s our A-list research team doing?
The Path To Bacteria Biofuel
There are many strains of E. coli (that’s short for Escherichia coli), some harmless and others notoriously responsible for severe food poisoning. They all have one thing in common, which is their ability to produce the long chains of carbon and hydrogen atoms found in petroleum, called fatty acids.
A key part of the challenge, as described by the Wyss Institute, is to get E. coli to produce fatty acids that are just the right length. Long chains containing more than 12 carbons are energy-dense but too gooey. Chains that are too short don’t store enough energy and vaporize too easily.
The research team, therefore, aimed at producing chains between four and 12 carbons long.
They achieved the result, an eight-carbon chain called octanoate (aka octanoic acid or more commonly, caprylic acid), by altering the metabolic pathway that converts carbon from sugar into fatty acids.
If you think of the pathway as a river, as Wyss suggests, you can visualize the chain growing longer as it flows downstream. By genetically engineering the pathway to form “dams” or tighten up, you shorten the process and therefore, shorten the length of the chain.
Caprylic acid only gets you part of the way to biofuel, though. it is a precursor that occurs naturally in some mammal milk as well as coconut and palm oil. It has a variety of uses including dyes, perfumes, detergents and pharmaceuticals, but not biofuels, at least not yet.
To get a step closer to a biofuel precursor, the team is working on a process to convert octanoate to alcohols, which Wyss describes as “just one chemical step away from octane.”
If it all works out, you can thank the National Science Foundation and the Department of Energy’s ARPA-E funding arm, both of which are supporting the project.
It’s An E. Coli World, We Just Live In It
The Harvard team has some company, by the way. Rice University researchers are working on new genetic pathways to get E. coli to produce more fatty acids, and over at the Department of Energy’s Joint BioEnergy Institute, researchers have been nudging a strain of E. coli to digest switchgrass and produce gasoline, diesel and jet biofuel.
Across the pond at the University of Exeter, researchers are working with DNA from E. coli to develop a process that could produce biofuel from straw or manure.
Researchers are looking into non-fuel uses for the bug, too, one example being a kind of self-assembling, sustainable ink under development at Tufts University.
It’s also worth noting that bacteria could help solve one of the challenges of a bio-based transportation landscape, and that is the crude glycerin byproduct generated by biorefining.
Unlike pure glycerin, crude glycerin has limited uses and global markets have been swamped with the stuff, but a research team at the University of Alabama has been developing a strain of bacteria commonly found in soil, which could be used to digest glycerin and produce butanol, propanediol, ethanol and acetic acid.
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