Journal article
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 > 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.
Language: | English |
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Year: | 2017 |
Pages: | 223-235 |
ISSN: | 10967176 and 10967184 |
Types: | Journal article |
DOI: | 10.1016/j.ymben.2017.10.002 |
ORCIDs: | Ødum, Anders Sebastian Rosenkrans |
1,2-propanediol Dihydroxyacetone Glycerol Saccharomyces cerevisiae Triosephosphate isomerase Yeast