Calorimetric analysis of saccharomyces cerevisiae strain pe-2 under specific metabolic stages and industrial relevant conditions

Abstract

Extreme conditions are expected during sugarcane ethanol production that make the process difficult to be modelled. Saccharomyces cerevisiae cells deal with many stressful factors during fermentation, such as high-cell density, inhibitory compounds, lack of essential nutrients, non-aseptic conditions, and high temperature. Despite a substantial number of studies regarding the development of mathematical models in recent years, the dynamic behavior of the process is not well comprehended under these stressful environments and constantly changing conditions. In this regard, this study aims to develop a mathematical model for the alcoholic fermentation process in a fed-batch bioreactor under conditions that mimic first-generation (1G) ethanol production in Brazil. This model will consider the thermal effects, energy balances, and substrate concentrations in the kinetic parameters of the process. Furthermore, we aim to fulfill the lack of experimental data regarding the heat released during cellular growth and ethanol production, applying a calorimetric analysis of the process under specific metabolic stages achieved via chemostat cultivations. For that, we propose the calorimetric investigation of the widely used industrial S. cerevisiae strain PE-2 using the validated setup reported by Schubert et al. (2007) in five distinct metabolic stages that decouple growth and ethanol production as far as possible to analyze them separately and determine their reaction enthalpies experimentally. This project also aims to validate energy and mathematical modelling in the industrial 1G ethanol production using previously developed synthetic molasses. Therefore, the proposed model complements the literature by accounting for the impact of essential process variables and the inclusion of energy balances on the traditional mathematical model parameters. (AU)