    4.2.3.3 | synthesis |
engineering of a functional 1,2-propanediol pathway through a combination of overexpression of genes involved in its synthesis from the key intermediate dihydroxyacetone phosphate and the manipulation of the fermentative glycerol utilization pathway, including the overexpression of methylglyoxal synthase, glycerol dehydrogenase, and aldehyde oxidoreductase. Rreplacement of the native Escherichia coli phosphoenolpyruvate-dependent dihydroxyacetone kinase with an ATP-dependent ihydroxyacetone kinase from Citrobacter freundii allows for higher 1,2-propanediol production. Ethanol is required as co-product, and inreases in 1,2-PDO titer and yield are achieved through the disruption of the pathways for acetate and lactate production. Manipulations result in an engineered Escherichia coli strain capable of producing 5.6 g/l 1,2-propanediol, at a yield of 21.3% w/w. This strain also performs well when crude glycerol is used as the substrate |
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