ED pathway

Fig. 4. Carbon transitions in the Embden-Meyerhof-Parnas (EMP) and the Entner-Doudoroff (ED) pathway. In the EMP pathway, Cl-labeled glucose is converted into 50% unlabeled and 50% C3-labeled pyruvate, while the ED pathway produces 50% unlabeled and 50% Cl-labeled pyruvate...

There are two pathways degrading glucose to pyruvate i.e., the Embden-Meyerhof(EM) pathway and the Entner-Doudoroff(ED) pathway. By the EM pathway, 2 mol of NADH are produced while 1 mol each of NADH and NADPH (Nicotinamide Adenine Dinucleotide Phosphate, reduced form) is produced by the ED pathway as follows. 

A variety of carbohydrate sources such as arabinose, fructose, galactose, mannitol, mannose, ribose, sorbitol and xylose are utilised by AAB through the hexose monophosphate pathway (De Lay et al., 1984), Embden-Meyerhof-Pamas (EMP) and Entner Doudoroff (ED) pathway (Attwood, van Dijken, Pronk, 1991). Acetobacter can also oxidise various organic acids into CO2 and H2O through the tricarboxylic acid (TCA) cycle, but like Glucombacter lacks a functional TCA cycle, which limits oxidation of organic acids (Seo et al., 2004). 

The ED pathway can be engineered for isoprene production via the MEP pathway, which can provide the balanced ratio of Pyr and G3P to increase the productivity of isoprene. EMP in tandem with the MEP pathway is commonly used for isoprene biosynthesis in E. coli. However, the highest isoprene production and yield were achieved from ED pathway, which were 3 and 6 times higher than those of EMP [72]. This is because imbalanced distribution of Pyr and G3P existed in... 

EMP, while Pyr and G3P were simultaneously generated in the ED pathway. Additionally, in terms of precursor generation and energy/reducing-equivalent supply, EDP + PPP was found to be the ideal feed module for MEP [72]. 

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