The typical production of biofuel uses expensive enzymes to break down cornstarch or sugarcane so that microbes can transform it into the chemicals needed for gasoline, diesel, and jet fuel. Not only is this process expensive, but it has also raised concerns over food security and the use of valuable agricultural land.
As a solution to these problems, researchers began inserting enzyme genes into the microbes so they would grow their own enzymes and independently convert the sugar into ethanol.
Using the same strategy, Jay Keasling and colleagues from the Joint BioEnergy Institute in Emeryville, California have found a way to create more common fuels. By injecting strains of E. coli with genes for three different metabolic pathways, Keasling enabled microbes to make the chemical precursor for gasoline, diesel, or jet fuel.
After adding the engineered E. coli to a biofuel plant called switchgrass, the researchers reported that the E. coli would grow on the grass and could generate all three fuels.
Although the microbes only produce about one-tenth of the enzymes needed to break down the sugars, and the fuel they generate is minimal, researchers believe this is an important step toward commercializing biofuels. Keasling plans to improve his experiment by engineering similar genes into yeast.