One of the five “thrust” areas of the GLBRC is focused on improving the conversion of biomass to fermentable sugars. Although enzymatic deconstruction is considered to be the most promising technology for this step, enzymes are still prohibitively expensive. Several labs in the GLBRC are pursuing approaches to reduce the cost of enzymes. Approaches include identifying the critical enzymes in commercial enzyme mixtures, bioprospecting in novel environments for catalytically more efficient and synergistic enzymes, engineering better enzymes, and producing enzymes in heterologous systems to reduce their production cost. As a first step toward the rational design of better enzyme mixtures, our lab is developing a “minimum” set of enzymes, which will form the base for the construction of an optimized, synthetic mixture. We are producing highly pure enzymes in both heterologous and homologous systems, and testing and optimizing their ratios with high throughput assays. Our starting point are the core cellulases (cellobiohydrolase, endoglucanase, beta-glucosidase), and the core hemicellulases (endo-xylanase and beta-xylosidase). Accessory enzymes include additional endoglucanases, enzymes that hydrolyze the side chain linkages of hemicelluloses, and nonenzymatic proteins.