(633b) Rewiring Yeast to Improve Cellobiose Fermentation

Sugars derived from plant cell walls are highly abundant in nature and hold promise to provide an abundance source for production of renewable fuels and chemicals. However, the cost and logistics of releasing these sugars from plant biomass remains prohibitive on commercial scales. The yeast Saccharomyces cerevisiae has a proven track record as a research platform and industrial host for production of biofuels and chemicals. Yet, S. cerevisiae is unable to utilize sugars released from the plant cell wall, i.e. cellobiose. Using pathways from Neurospora crassa, we have engineered S. cerevisiae to ferment cellobiose. However, having never used cellobiose as a carbon source, S. cerevisiae ferments this “masked” source of glucose slowly. We have used S. cerevisiae as a “blank slate” to understand the key bottlenecks in cellobiose utilization. I will present our recent work that combines directed evolution, pathway engineering, and systems biological methods to further improve the fermentation performance of cellobiose-utilizing S. cerevisiae.