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Enhanced production of (R)-1,2-propanediol by metabolically engineered Escherichia coli
1Department of Chemical Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706-1691, USA.
Biotechnology Progress
|December 2, 2000
Summary
Engineered E. coli produced (R)-1,2-propanediol from glucose. By eliminating lactate and constructing a complete pathway, titers increased to 4.5 g/L, showing promise for bio-based chemical production.
Area of Science:
- Biotechnology
- Metabolic Engineering
- Synthetic Biology
Background:
- 1,2-Propanediol (1,2-PD) is a key commodity chemical typically produced from petroleum-based propylene.
- Previous work demonstrated enantiomerically pure (R)-1,2-PD production from glucose using engineered E. coli with specific genes.
- Further optimization was needed to enhance 1,2-PD yield and titer in microbial hosts.
Purpose of the Study:
- To improve the production of 1,2-propanediol (1,2-PD) in engineered Escherichia coli (E. coli).
- To investigate strategies including host strain improvement and pathway construction for enhanced 1,2-PD biosynthesis.
- To optimize bioprocessing conditions for increased final product concentration.
Main Methods:
- Engineered E. coli strains by eliminating lactate production pathways (mutations in lactate dehydrogenase and glyoxalase I).
- Constructed a complete biosynthetic pathway for 1,2-PD from dihydroxyacetone phosphate via coexpression of methylglyoxal synthase (mgs), glycerol dehydrogenase (gldA), and either yeast alcohol dehydrogenase (adhI) or E. coli 1,2-propanediol oxidoreductase (fucO).
- Performed fed-batch fermentation using the optimized strain (mgs, gldA, fucO) to evaluate bioprocessing improvements.
Main Results:
- Mutations to reduce lactate production unexpectedly led to basal 1,2-PD formation in one E. coli strain without added genes.
- The complete pathway, coexpressing mgs, gldA, and fucO, significantly improved 1,2-PD production compared to previous methods (0.7 g/L).
- Fed-batch fermentation achieved a final titer of 4.5 g/L of (R)-1,2-PD with a yield of 0.19 g/g glucose.
Conclusions:
- Metabolic engineering strategies, including host modification and pathway reconstruction, are effective for enhancing bio-based 1,2-PD production.
- The engineered E. coli strain and optimized fermentation process provide a foundation for further development of sustainable 1,2-PD manufacturing.
- This research contributes to the advancement of microbial production of valuable chemicals from renewable resources.