A strain of the bacterium Escherichia coli has been genetically engineered to break down switchgrass into sugars, and then convert those sugars into three types of biofuel. This consolidated process, which does not require the addition of enzymes, could lower the cost of producing fuels from biomass.

Jay Keasling at Lawrence Berkeley National Laboratory in Berkeley, California, and his colleagues designed their bacterium to produce four enzymes that digest cellulose and hemicellulose in switchgrass (Panicum virgatum) that has been pretreated with ionic liquids. They introduced into the E. coli three biochemical pathways that turn sugars into either fuel or fuel precursors for petrol, diesel and jet engines.

Further improvements, such as finding more and better enzymes, are needed to boost biofuel yields, the authors say.

Proc. Natl Acad. Sci. USA 10.1073/pnas.1106958108 (2011)