(216c) Construction of a Xylose and Arabinose Utilizing Zymomonas Mobilis Strain for Commercial Use in Fuel Ethanol Production

Zymomonas mobilis is an obligate and rapid producer of ethanol but its normal substrate range is limited to glucose, fructose and sucrose.  The addition of exogenous genes encoding enzymes to allow the use of xylose and arabinose to Z. mobilis was shown to be effective over 10 years ago so the main tasks in strain development have been to reach rates of 5 carbon sugar metabolism that are compatible with those required to be economically favorable in fuel ethanol production and to do that in strains that are compatible with the nutrient and inhibitor set that is present in the cellulosic substrate to ethanol process.  The combination of iterative expression level changes in genes in the 5 carbon pathway, knock out of toxin producing genes, adaptation to growth on the 5 carbon substrates, and adaptation to growth in cellulosic process hydrolysate has produced several viable strains.  Strains and process conditions that produce desired volumetric productivity have been created and tested at the pilot plant scale.