Application of system analysis to the process of simultaneous saccharification and fermentation of starch to ethanol utilizing genetically modified microorganisms

Abstract

ABSTRACT The instability of the market of the petroleum raises the importance of research of alternative production processes of renewable liquid fuels. The production of etanol by fermentation, using starch as substrate, has been studied intensively in the last years, resulting in a simultaneous process of saccharification and fermentation of the starch to etanol using modified microorganisms. The objective of this work was to develop a mathematical model for the direct bioconversion of starch to etanol being used Saccharomyces cerevisiae YPB-G strain that secreted a bifunctional protein with enzymatic activity of the B. subtilis alpha-amylase and the A. awamori glucoamylase. The modeling strategy consisted of dividing the process in two hierarchic levels of knowledge that would be studied separately, and later unified through the glucose balance, and enzymes synthesis balance. The model was validated with the experimental data and was compared with cybernetic modeling results for the same system. Keywords: Ethanol, Simultaneous saccharification and fermentation, Saccharomyces cerevisiae YPB-G, System analysis.