Fig. 1
From: Metabolic engineering of Escherichia coli for production of n-butanol from crude glycerol
The central metabolic pathways of E. coli connecting glycerol catabolism to n-butanol synthesis. The catabolic route of glycerol includes the glpK-glpD and the gldA-dhaKLM pathways. The heterologous pathway for the synthesis of n-butanol is composed of phaA, hbd, crt, ter, and adhE2 genes (dotted line). The genes involved in the metabolic pathways: aceEF-lpdA*: pyruvate dehydrogenase complex; adhE, aldehyde–alcohol dehydrogenase; adhE2, butyraldehyde–butanol dehydrogenase; crt, crotonse; hbd, 3-hydroxybutyryl-CoA dehydrogenase; ldhA, lactate dehydrogenase; fba, fructose bisphosphate aldolase; fbp, fructose 1,6-bisphosphatase; frdABCD, fumarate reductase; pflB, pyruvate-formate lyase; gltA, citrate synthase; glpF, glycerol facilitator; gldA, glycerol dehydrogenase; dhaKLM, dihydroxyacetone kinase; glpK, glycerol kinase; glpD, glycerol 3-phosphate dehydrogenase; pgi, phosphoglucose isomerase; pgl, lactonase; phaA, acetoacetyl-CoA thiolase; pta, phosphate acetyltransferase; ter, trans-enoyl-CoA reductase; udhA, transhydrogenase; zwf, glucose-6-phosphate dehydrogenase. The undesired genes in the pathways are deleted as marked with “X.” ACE acetate; EtOH ethanol; DHAP dihydroxyacetone phosphate; FDP fructose 1,6-bisphosphate; F6P fructose-6-phosphate; LAC lactate; FOM formate; G6P glucose-6-phosphate; CIT citrate; OAA oxaloacetate; PEP phosphoenolpyruvate; 3-PGA 3-phosphoglyceraldehyde; PYR pyruvate; SUC succinate