A High-Throughput Approach for Modeling and Simulation of Homofermentative Microorganisms Applied to Ethanol Fermentation by S. cerevisiae

The development of dependable mathematical models to describe cell metabolism dynamics is essential to ensure the success of bioprocess-enhancement strategies. Regarding ethanol fermentation, for example, growth models must consider the different constraints imposed on the microbial population, such as the ethanol inhibition. The approach used to obtain sufficient experimental data also plays an important role as it needs to be descriptive and reliable. This work proposes the modeling of homofermentative microorganisms based solely on the determination of CO2 mass produced during different fermentation conditions. Substrate and product inhibition were investigated for two industrial yeast strains. The methodology provided consistent information and Monod-type kinetic models for both strains were identified, which illustrated qualitatively the influence of the media composition in terms of inhibition parameters. The most promising strain was then cultivated in a 5-L bioreactor under anaerobic conditions. Good agreement with the anaerobic bioreactor experimental data was achieved in the validation step, ensuring the reliability of the proposed strategy. Furthermore, a kinetic model extension was also developed, which proved to be capable of describing a micro-aerated culture. This modeling approach can provide important information required for the scaling-up and intensification of bioprocesses employing homofermentative microbes.