Promotie I. Papapetridis: ethanol

14 juni 2018 10:00 - Locatie: Aula, TU Delft - Door: webredactie

Optimizing ethanol yield in Saccharomyces cerevisiae fermentations by engineering redox metabolism. Promotor 1: Prof.dr. J.T. Pronk (TNW); Promotor 2: A.J.A. van Maris (KTH Sweden).

Mankind’s increasing energy demands require a shift of the current, oil-powered, economy to more sustainable energy sources. Biofuels offer a lower carbon footprint than fossil fuels, in combination with compatibility with current internal combustion engine technology. Bioethanol is, by-volume, the biofuel with the highest annual production, with an estimated 100 billion liters produced annually. This biofuel is currently produced by microbial fermentation of simple sugars (1st generation) or agricultural waste (2nd generation) using baker’s yeast. In these processes, the feedstock represents the largest cost contributor. To improve process economics, a maximization of the ethanol yield on used feedstock is of paramount importance. In this thesis, modern genetic engineering tools were used to modify the metabolism of this yeast, in order to generate variants with increased ethanol yield. Two concepts, based on previous TU Delft findings, were optimized for transfer to industrial processes. The first one was based on the optimization of CO2 fixation by yeast, using enzymes derived from a plant (spinach), autotrophic bacteria and Escherichia coli. The second was based on the optimization of acetic acid reduction, a common yeast inhibitor present in agricultural waste, to generate more ethanol and detoxify fermentation media. The optimized concepts presented in this thesis should be directly transferable to industrial strains and processes in order to improve industrial bioethanol production. 

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