Development of Recombinant Yeast for Cellulosic Ethanol Production From Concept to Large-Scale Production Nancy W. Y. Ho Laboratory of Renewable Resources Engineering (LORRE) Purdue University West Lafayette, Indiana, 4796 Phone & Fax 765-494-746 nwyho@purdue.edu www.nancyho.info
Composition of cellulosic biomass Cellulose 45% Hemicellulose 25% Other 5% Lignin 25%
NADPH (NADH) NADP (NAD) D-Xylose Xylitol Xylose Reductase (XR) Xylose isomerase Xylitol Dehydrogenase (XD) NAD + NADH + H + ATP ADP D-Xylulose Xylulokinase (XK) D-Xylulose-5-Phosphate Pentose Phosphate Pathway The xylose metabolic pathway in yeast
Cofermentation of Glucose and Xylose by 14(pLNH32) 1 8 Glucose Xylose Ethanol Glycerol Xylitol Co-fermentation of glucose and xylose By 14(pLNH32) Concentration (g/l) 6 4 2 1 2 3 4 5 6 Fermentation time (hours)
Cofermentation of Glucose and Xylose by Untransformed Strain 14 1 8 Glucose Xylose Ethanol Co-fermentation of Glucose and xylose by Un-transformed Parent strain 14 Concentration (g/l) 6 4 2 2 4 6 8 Fermentation time (hours)
1993-1996 Development of stable yeast containing high-copy-number XR, XD, and XK genes integrated into the yeast chromosomes
Cofermentation of glucose and xylose by 14 (LNH-ST) 8 Glucose Xylose Ethanol Xylitol Glycerol 6 Co-fermentation of glucose and xylose by 14(LNH-ST) Concentration (g/l) 4 2 2 Fermentation Time (hr)
1997-1999 Large-scale screening for better yeasts with no legal constraints for converting cellulosic sugars (mixed sugars recovered from cellulosic biomass) to ethanol
7 5 6 New stable yeast 424A(LNH-ST) for co-fermentation of glucose and xylose to ethanol g/l 5 4 3 Glucose Xylose Glycerol Ethanol O.D. 4 3 2 O.D. (Klett unit) 2 1 1 5 1 15 2 25 3 Time (hours)
Fermentation of hydrolysates, prepared by various Methods, with 424A(LNH-ST)
Fermentation of softwood hydrolyzate by S. cerevisiae 424A(LNH-ST) 6 5 Fermentation of softwood hydrolysates by yeast 424A(LNH-ST) Concentration (%) 4 3 Glucose Xyl.Man.Gal. Xylitol Glycerol Ethanol 2 1 1 2 3 4 5 Fermentation Time ( hr)
Liquid hydrolyzate 5:5 ph adjustment 4 Xylose Glycerol Ethanol Fermentation of Cellulosic wastes from a paper factory by 424A(LNH-ST) g/l 3 2 1 1 2 Time (hours)
Expression profile of S. cerevisiae 424A(LNH-ST) co-fermenting glucose and xylose. Clustering by K- means and measure similarity by Pearson correlation
Large-Scale Production of Cellulosic Ethanol Our yeast has been used by Iogen to produce cellulosic ethanol from wheat straw in their demonstration plant in Canada since April 24 And Iogen also told ASM News, Many groups have made recombinant microbes to do this*, but Ho s yeast is the best we have tested. * To convert cellulosic biomass to ethanol
22-present Successful engineering of yeasts capable of producing high-value co-products during grain-ethanol or cellulosic-ethanol production
12 35 6 1 3 Production of coproduct during cofermentation of glucose and xylose by 424A(LNH-ST) Activity (U/ml) 8 6 5 4 g/l 3 Glucose Xylose Glycerol Ethanol Xylitol O.D. Co-product 25 2 15 O.D. (Klett unit) 4 2 1 2 1 5 5 1 15 2 25 3 Time (hours)
1995-2 Genetic engineering of Saccharomyces Yeast for converting glucose or glucose/xylose to lactic acid
Co-fermentation of glucose and xylose by genetically engineered Saccharomyces yeast to lactic acid 5 Glucose Xylose Lactic acid Ethanol Co-fermentation of glucose And xylose by genetically engineered Saccharomyces yeast to lactic acid 4 3 g/l 2 1 5 1 15 2 25 3 35 Time (hours)
Conversion of SC hydrolyzate to lactic acid by genetically modified S. cerevisiae 3 Conversion of CS hydrolysates to lactic acid by genetically modified S. cerevisiae 25 2 Xylose Lactic acid Acetic acid g/l 15 1 5 1 2 3 4 5 Time (hours)
2-Present Further genetic engineering of the best yeast, 424A(LNH-ST), to improve its xylose fermentation by developing a xylose-specific transport and make it able to ferment two other minor sugars, L-arabinose and galactose, effectively.
Acknowledgement MAJOR PARTICIPANTS SINCE 198 Stuart A. Rosenfeld Zhengdao Chen Panayiotis E. Stevis Adam P. Brainard Sue-Fan Chang Miroslav Sedlak Our early work, prior to 199, was mostly supported by DOE and USDA. EPA also provided us a grant for three years for screening the most effective yeast for xylose fermentation. Overall, we are most indebted to the NRI program of USDA, particularly its Biobased Products and Bioenergy Research Program, that has persistently supported our research on the development of recombinant yeast since the early 198s.