Thursday, May 5, 2011: 3:30 PM
Grand Ballroom B, 2nd fl (Sheraton Seattle)
Lignocellulosic biomass consisting of cellulose, hemicellulose, and lignin is a potential sustainable source of mixed sugars for fermentation to fuels and chemicals. Co-utilization of all the available sugars such as glucose, xylose, and arabinose present in the lignocellulosic hydrolysates is critical to the overall economics of the fermentation process. Here I will present two new strategies for efficient utilization of lignocellulosic biomass. The first strategy involves the construction of a recombinant yeast strain capable of simultaneously utilizing cellobiose and xylose. Cellobiose is an intermediate product from enzymatic hydrolysis of cellulose, which is further converted to glucose by b-glucosidase. By co-expressing a recently discovered high-affinity cellodextrin transporter and b-glucosidase in an engineered xylose-utilizing yeast strain, we demonstrated that a mixture of sugars including cellobiose and xylose can be simultaneously consumed by the corresponding recombinant yeast to produce ethanol with high yields and productivity (1). The second strategy involves the construction of a recombinant yeast strain capable of simultaneously utilizing glucose, xylose, and arabinose. Specifically, we identified and cloned two novel xylose-specific transporters and one arabinose-specific transporter (2). In addition, we are using DNA assembler based strategy to construct and optimize the metabolic flux through the xylose/arabinose utilizing pathway. To further facilitate metabolic engineering, genome-scale modeling was used to investigate and evaluate various gene knockout strategies. For both strategies, results from both laboratory and industrial strains will be discussed and compared.
- S. Li, et al. Molecular Biosystems, 6, 2129 (2010).
- J. Du, et al. Molecular Biosystems, 6, 2150 (2010).