Ethanol production using Zymomonas mobilis: Development of a kinetic model describing glucose and xylose co-fermentation

Abstract

Reliable kinetic models are important for the design and optimisation of lignocellulosic ethanol production. A new kinetic model describing ethanol production using Zymomonas mobilis ZM4(pZB5) that is applicable to single (glucose or xylose) or mixed (glucose and xylose) substrate fermentations is developed. This work extends previous contributions through consideration of an empirical term for the preferential usage of glucose when compared to xylose as well as the prediction of the production rate of xylitol. Kinetic model parameters are obtained through kinetic fitting using experimental data available in the literature (seventeen fermentations in batch or continuous operation). The average coefficient of determination of xylose, xylitol, ethanol, glucose and biomass predictions using the kinetic model developed in this work was 0.984. Furthermore, it is demonstrated that through the inclusion of xylitol production and the inhibition of xylose consumption by xylitol in the kinetic model the productivity of ethanol may be accurately estimated.