A Simple Metabolic Flux Balance Analysis of Biomass and Bioethanol Production in Kluyveromyces Marxianus ATCC 26548 Batch Culture

Authors: 
Abd Karim, K., Universiti Malaysia Perlis
Tompang, M. F., Universiti Sains Malaysia
Harun @ Kamaruddin, A., Universiti Sains Malaysia

The yeast Kluyveromyces marxianus ATCC 26548 has been considered as a potential microorganism for many applications in industrial bioprocesses especially in bioethanol production due to its special traits as compared to others. Mathematical approach is used to analyze the flow of metabolites in biological system in order to improve desired product yield as well as the overall production process, thus development of a simple model could lead to sustainability and practicability of the process. In this study, the comparative analysis of a simple metabolic network and a black box description is carried out in order to evaluate the yeast growth and bioethanol production in batch fermentation. Metabolic flux balance methodology has shown to give more accurate estimation with complete analysis of the reaction rates. Furthermore, good interpretation of the yeast behavior in batch culture at different glucose concentrations was achieved based on its stoichiometric reaction analysis. No significant changes in biomass growth when glucose concentration is increased at a controlled aeration above 60% air saturation, but resulting in higher ethanol production in low dissolved oxygen concentration. The biomass and ethanol production are mostly depended on oxidative and reductive catabolism, respectively, which are controlled by glucose and oxygen uptake rates. Therefore, the analysis of reaction rates in minimal metabolic network provided substantial about the physiology of cultured yeast cells, and the production of bioethanol and biomass could be improved by changing the batch experimental conditions.