Published on March 28th, 2014 | by Tina Casey7
Exotic Rainforest Bug Could Break Biofuel Bottleneck
March 28th, 2014 by Tina Casey
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.
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.
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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