Tuesday, May 1, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Cargill’s CB1 yeast platform has many characteristics required in cost effective, robust industrial fermentation processes. The first commercial application of this platform was introduced in 2008 for lactic acid production, where a CB1 yeast engineered to produce lactic acid replaced the incumbent bacterial technology. Commercially important characteristics of CB1 yeast include high product yield and productivity, and tolerance to low pH, ethanol, high temperature and common inhibitors in hydrolysates. As a result, these properties make it a good choice as a biocatalyst for cellulosic ethanol fermentation. Using metabolic engineering, mutagenesis and selection, and evolution, Cargill has developed CB1 for this purpose and demonstrated ethanol fermentation in full-strength, non-detoxified corn stover hydrolysate at a rate of >0.5 g/L*h and >80% yield. In these fermentations xylose and glucose are co-utilized and fermented to ethanol. We have further improved the strains and tailored them for fermentation of other types of hydrolysates. Ethanol fermentation results in different hydrolysates will be shown and discussed. Moreover, a significant amount of arabinose is present in some feedstocks, such as corn fiber. Arabinose to ethanol fermentation by engineered CB1 will be presented as well. The physiology of CB1 and an extensive toolbox for strain improvement make this yeast a very useful platform organism for the production of biofuels and chemicals.