Evaluation of a Kinetic Model for Computer Simulation of Growth and Fermentation by Scheffersomyces (Pichia) stipitis Fed D-Xylose

Scheffersomyces (formly Pichia) stipitis is a potential biocatalyst for converting lignocelluloses to ethanol because the yeast natively ferments xylose. An unstructured kinetic model based upon a system of linear differential equations has been formulated that describes growth and ethanol production as functions of ethanol, oxygen, and xylose concentrations for both growth and fermentation stages. The model was validated for various growth conditions including batch, cell recycle, batch with in situ ethanol removal and fed-batch. Integrating basic kinetic and physiological yeast properties, the model is an important predictive tool for simulating and optimizing various culture conditions and evaluating various bioreactor designs for ethanol production.