Sunday, May 3, 2009
2-45
Engineering E. coli to digest and utilize cellulose and hemicellulose as sole carbon sources
Gregory Bokinsky, Departments of Chemical Engineering and Bioengineering, California Institute for Quantitative Biosciences, 204 Stanley Hall, #3220, Berkeley, CA 94720-3220, Swapnil Chhabra, Fuels Synthesis Division, Joint BioEnergy Institute, 5885 Hollis Street, Fourth Floor, Emeryville, CA 94608, and Jay D. Keasling, Departments of Chemical Engineering and Bioengineering, UC-Berkeley; Lawrence Berkeley National Laboratory, EmeryStationEast, 5885 Hollis St, 4th floor, Emeryville, CA 94608.
E. coli is widely used for the production of small molecules via metabolic engineering. However, it is unable to use plant biomass as a feedstock. We are engineering E. coli to enable growth on cellulose and hemicellulose in two steps: 1) harnessing secretion systems to export milligram quantities of glycoside hydrolases and other biomass degrading enzymes cloned from cellulolytic organisms; 2) enabling E. coli growth on the soluble oligosaccharide products of degradation by incorporating permease and beta-glucosidase genes into the chromosome. In order to enhance growth on crystalline substrates such as cellulose, we have also engineered membrane attachments for the secreted enzymes to allow assembly into multienzyme complexes, which are analogous to cellulosomes found in Clostridia species. These modifications can be incorporated into E. coli strains able to generate valuable compounds including fuels, which will enable production directly from plant biomass.