Aßkamp, Maximilian R.

Islam, Zia-Ul

Klein, Mathias

Nevoigt, Elke

Ødum, Anders Sebastian Rosenkrans

Metabolic Engineering

Zia-ul Islam

Mathias Klein

Maximilian R. Aßkamp

Anders S.R. Ødum

Elke Nevoigt

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A modular metabolic engineering approach for the production of 1,2-propanediol from glycerol by Saccharomyces cerevisiae

Compared to sugars, a major advantage of using glycerol as a feedstock for industrial bioprocesses is the fact that this molecule is more reduced than sugars. A compound whose biotechnological production might greatly profit from the substrate's higher reducing power is 1,2-propanediol (1,2-PDO). Here we present a novel metabolic engineering approach to produce 1,2-PDO from glycerol in S. cerevisiae. Apart from implementing the heterologous methylglyoxal (MG) pathway for 1,2-PDO formation from dihydroxyacetone phosphate (DHAP) and expressing a heterologous glycerol facilitator, the employed genetic modifications included the replacement of the native FAD-dependent glycerol catabolic pathway by the `DHA pathway´ for delivery of cytosolic NADH and the reduction of triosephosphate isomerase (TPI) activity for increased precursor (DHAP) supply. The choice of the medium had a crucial impact on both the strength of the metabolic switch towards fermentation in general (as indicated by the production of ethanol and 1,2-PDO) and on the ratio at which these two fermentation products were formed. For example, virtually no 1,2-PDO but only ethanol was formed in synthetic glycerol medium with urea as the nitrogen source. When nutrient-limited complex YG medium was used, significant amounts of 1,2-PDO were formed and it became obvious that the concerted supply of NADH and DHAP are essential for boosting 1,2-PDO production. Additionally, optimizing the flux into the MG pathway improved 1,2-PDO formation at the expense of ethanol. Cultivation of the best-performing strain in YG medium and a controlled bioreactor set-up resulted in a maximum titer of &gt; 4gL-1 1,2-PDO which, to the best of our knowledge, has been the highest titer of 1,2-PDO obtained in yeast so far. Surprisingly, significant 1,2-PDO production was also obtained in synthetic glycerol medium after changing the nitrogen source towards ammonium sulfate and adding a buffer

Online Research Database In Technology

http://orbit.dtu.dk/ws/files/138291532/A_modular_metabolic_engineering_approach_for_the_production_of_1_2_propanediol_from_glycerol_by_Saccharomyces_cerevisiae.pdf

A modular metabolic engineering approach for the production of 1,2-propanediol from glycerol by Saccharomyces cerevisiae

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Online Research Database In Technology