초록
<P>Escherichia toll was metabolically engineered to produce industrially important platform chemicals, 3-hydroxypropionic acid (3-HP) and malonic acid (MA), through the beta-alanine (BA) route. First, various combinations of downstream enzymes were screened and BA pyruvate transaminase (encoded by pa0132) from P. aeruginosa was selected to generate malonic semialdehyde (MSA) from BA. This platform strain was engineered by introducing E. coli MSA reductase (encoded by ydf G) to reduce MSA to 3-HP. Replacement of native promoter of the sdhC gene with the strong trc promoter in the genome increased 3-HP production to 3.69 g/ L in flask culture. Introduction of E. coil semialdehyde dehydrogenase (encoded by ynel) into the platform strain resulted in the production of MA, and additional deletion of the ydf G gene increased MA production to 0.450 g/L in flask culture. Fed-batch cultures of final engineered strains resulted in the production of 31.1 g/L 3-HP or 3.60 g/L MA from glucose.</P>