Key Gene to Overcome Microbial Limitations in Cellulosic Ethanol Production

Researchers at the Oak Ridge National Laboratory's Bioenergy Research Center (United States) announced that they have identified a Zymomonas mobilis gene which could hold a key for more effective microbial utilization of pretreated lignocellulosic biomass for biofuel-ethanol production. Before lignocellulosic biomass (such as corn stover or switchgrass) can be processed for ethanol fermentation, it undergoes pretreatment "to loosen the cellular structure enough to extract the sugar from cellulose." According to co-researcher, Steven Brown, these treatments add new challenges because, although they are necessary, they create a range of chemicals known as inhibitors that stall or stop (ethanol-fermenting) microorganisms like Zymomonas mobilis from performing the fermentation. Acetic acid (or acetate) is one such inhibitor.

By using the tools of systems biology, the scientists were able to characterize a mutant of Zymomonas mobilis (AcR) and demonstrated that acetate tolerance has potential importance in biofuel development. The researchers developed a strain of Z. mobilis which becomes acetate-tolerant when the key gene is over-expressed; they also found that the mutant gene created a similar impact when it was inserted into yeast. The full paper is published as an open access article in the Proceedings of the National Academy of Sciences (PNAS) (URL above).