Published on March 28th, 2014 | by Tina Casey


Exotic Rainforest Bug Could Break Biofuel Bottleneck

March 28th, 2014 by  

Scientists at Lawrence Livermore National Laboratory have discovered how to help E. coli bacteria squirt out advanced biofuels, and the key is held by a pair of genes found in a soil-dwelling bacterium from a rainforest in Puerto Rico. The finding could enable the lab to shoot through a bottleneck that has been stumping researchers, who have been trying to figure out how to make E. coli survive a catch-22 in the biofuel production process.

For those of you keeping score at home the bacterium from Puerto Rico is Enterobacter lignolyticus, and if you’re wondering how this bug came across the lab’s radar out of all the other microbes in the world, that’s a good question. Rainforest soils are known as fertile harbors for microorganisms that can break down lignin (the tough outer walls of plant cells) in an anaerobic (oxygen-free) environment, and researchers poked around in rainforest soils until they found a likely prospect.

E coli biofuel breakthrough

E. coli biofuel breakthrough (cropped) courtesy of LLNL.

The E. Coli Biofuel Catch-22

Lawrence Livermore researchers have developed a biofuel strategy based on ionic liquids, which refers to salts in liquid form.

Ionic liquids are used to extract cellulose from biomass which is all well and good in terms cost-effectiveness for the initial stages of biofuel production,  but there’s a catch.

The bottleneck pops up when the next stage comes along, in which E. coli microbes are used to break down the cellulose into sugars. E. coli can convert those sugars into biofuels under certain conditions, but a salty environment is not optimal for strains native to the U.S.

To work around that you have to subject the cellulose to a series of washings before you get to the fermentation stage, and that of course increases the cost of the process.

The alternative is to fortify E. coli against the toxic properties of ionic liquids, and that where the pair of genes from Enterobacter lignolyticus comes in.

So far, the team has succeeded in boosting production of a terpene-based biofuel with E. coli modified by the new genes.

The team also found that the microbe-based approach resulted in a boost for overall efficiency because with the ionic liquid remaining in the process, other less productive microbes are unable to survive and compete with the enhanced E. coli.

We Built This Amazing Biofuel-Producing Bug!

Since Livermore is a federal lab, you won’t be surprised to know that us taxpayers have footed the bill for this research, through the Department of Energy’s Office of Science.

It’s also worth noting that even before the introduction of the new genes, this particular strain of E. coli had been engineered to digest cellulosic biomass from switchgrass by researchers with the Joint Bioenergy Institute (JBEI), which is headed up by the Energy Department’s Berkeley Lab.

Among many other projects, the folks at JBEI are responsible for a promising breakthrough in boosting sugar production in plant cell walls.

Other paths to E. coli biofuel production are being pursued at Rutgers University and Harvard University among others.

As for switchgrass, back in 2008 the US Department of Agriculture estimated that this non-food, drought resistant plant could replace up to 30 percent of domestic petroleum consumption, so hold on to your hats.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • Burnerjack

    When the discussion shifts to “biofuels”, it invariably infers that these biofuels are pollution free. They are not. While biodiesel is cleaner, it is not clean. If we are concerned with environmental impacts, fine. “Hat’s off”. If we are concerned with the geopolitical impacts of Big Oil, then say so. Lessening one’s dependency on one oil fuel for an increase on another could hardly be coined “green”.
    Unless this ecoli is spewing hydrogen….
    paulsnookes, IMNSHO, has an excellent point. Beyond the possible unintended ramifications he alluded to, I find it the height of human arrogance to conclude that human bioengineering could hold anywhere near the “wisdom” of biollions of years of trial and error. Should an error occur and be unleashed the result could literally be of apocalyptic proportions. Risk/reward ratio not so good.

    • Bob_Wallace

      The carbon in the biofuel is carbon already “de-sequestered”.

      If we can cycle atmospheric carbon through organisms and engines and avoid extracting more carbon from below ground we win.

      We win one battle in the greater war. There are other battles to be fought.

      • Burnerjack

        If that’s the case, go hydrogen and then there is no need to take such risks.

  • paulsnookes

    I think this is TOTALLY insane. What happens when (not if) this bio-fuel producing bug escapes into the wider environment and start pumping out bio-fuel. I can’t believe that we are this stupid. Or maybe it’s me. Have I misunderstood something obvious?

    • Peter Gray

      Yes, you have misunderstood something obvious. Several things, in fact.

      First, this scary bug has already escaped into the wider environment, since that’s where it was found. It’s probably been around in some version for thousands if not millions of years. Yet something has prevented it from going crazy and coating the planet with biofuels (which, by the way, would quickly serve as food for other organisms, instead of accumulating in noticeable quantities). That something is called “competition,” and it’s alluded to in the article.

      Second, when we modify microbes to make them produce valuable products, whether by conventional breeding or through scary-sounding bioengineering, we invariably make them less competitive with their wild cousins. For the same reason, when a few domestic cattle escape, they don’t take over the ecosystem and crowd out all the deer and elk.

      The big challenge is not in preventing Frankenstein bugs from taking over the outside world, but in preventing wild strains from contaminating the process and destroying those productive, but weaker engineered bugs. That’s why it can be important to find another trait, such as salt tolerance, that gives the domestic organism a survival advantage in human-created conditions.

      It’s a big mistake – for the environment, the economy, and human health – to have a knee-jerk reaction against anything and everything that could be described as “genetic modification” or “bioengineering.” Please educate yourself. A good start would be this speech in early 2013 by former anti-GMO activist Mark Lynas:

  • Michael Berndtson

    Well written. Funny thing about biology, it’s loaded with jargon. Jargon can become currency for those who dabble in words. Then again, things have to be named. So there’s that. Your post did a great job keeping it simple, informative, and amazingly (or maybe seemingly) accurate. I’m not a biologist, but have had to deal with biology and biologist all my career in the environmental business. Mostly in bioremediation of soil and groundwater, impacted by whatever spilled. Anytime I don’t have to read 10,000 words on soil microbiology – where most of the words are Latin and the rest seem to be Greek – because it was nicely summarized – I’m happy.

    My suggestion to the kids out there in internet land who are interested in environment and energy at either the science or engineering levels – take lots of biology courses. A really good reason is that chemical engineering, the discipline responsible for turning a reactant into a product at volumes bigger than what can fit inside a laboratory beaker, has dovetailed biology more and more into its curriculums. And most important, scale up (going from lab to processing plant) is one of the hardest nuts to crack for commercializing a product or process. For confirmation on the last sentence, just ask Craig Venter and Exxon. Scale up is the goofy thing limiting algae fuel’s success.

    • Jim Nelson

      Well-written popular science is easier to read than jargon. But some writers go overboard, and the mixed metaphors defeat their purpose. In this article we are encouraged to “keep score at home” of what’s on a radar screen, told that a bottleneck “pops up” at a stage, and expected to figure out what a “fertile harbor” is. Let’s at least keep the metaphors meaningful and mutually consistent. Nor is there any need to get too folksy by using “us” as a subject: “us taxpayers have footed the bill.”

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