Researchers with the U.S. Department of Energy's Joint BioEnergy Institute (JBEI) have engineered the first strains of e.coli bacteria that can digest switchgrass biomass and synthesize its sugars into gasoline, diesel and jet fuel. And all without having to add expensive enzyme additives.
The upshot? The cost of switchgrass-based biofuel could be greatly reduced and help it compete with fossil fuel-based transportation fuels. JBEI CEO Jay Keasling explained in a recent announcement the use of e.coli has allowed researchers to "reduce fuel production costs by consolidating two steps -- depolymerizing cellulose and hemicellulose into sugars and fermenting the sugars into fuels -- into a single step or one-pot operation."
This research milestone, which was announced two weeks ago, comes at a time when switchgrass continues to gain credibility as a viable next-generation cellulosic feedstock. A new research review published today in GCB Bioenergy not only confirms the viability of switchgrass, but adds that it may have greater carbon emission fighting abilities than other alternatives.
How the e.coli bacteria does its job
The cellulose and hemicellulose are embedded in woody material called lignin found in plant biomass, making it a challenge to extract. Once the cellulose and hemicellulose have been isolated they're converted into simple sugars and then turned into fuel.
The folks at JBEI have been pre-treating the biomass with molten salt to dissolve it, then engineer a single microorganism that can digest the biomass and produce hydrocarbons that have the same properties found in petrochemical fuels, according to the research center. The researchers engineered a strain of e.coli that can use the cellulose and hemicellulose fractions of switchgrass that's been pre-treated with molten salt.
E.coli has been used in the past to produce gasoline and diesel from sugars. But this is the first demonstration of the bacteria to produce all three varieties of transportation fuels. Researchers says the techniques used in this case should be adapted to other microbes, which could the production of advance biofuels progress towards commercial viability. According to JBEI, researchers will focus their efforts on increasing yields of the fuels they can synthesize from switchgrass.
Photo: Lawrence Berkeley National Laboratory