Metabolic engineering of acetate-production pathways for the production of isoamyl acetate and succinate in Escherichia coli
Dittrich, Cheryl Renee
Master of Science
Products derived from the central aerobic metabolic pathway in Escherichia coli often compete with the acetate-producing pathways poxB and ackA-pta for glucose. The production of isoamyl acetate from acetyl-CoA by ATF2, a yeast alcohol acetyltransferase, was a model system to demonstrate the beneficial effects of reducing aerobic acetate production. Ester production was 80% higher in the poxB, ackA-pta strain (0.18 mM) than found in the single ackA-pta mutant, when both overexpressed the PDH complex, panK, and ATF2. Anaerobically, succinate was produced alongside isoamyl acetate to maintain the proper redox balance between NADH and NAD+. The two compounds could be easily separated in an industrial setting because of the difference in their volatilities. An ldhA, adhE double mutant strain served as the control strain to test the effect of an additional ackA-pta mutation. The triple mutant produced 36% more ester (9.4 mM) and 7 times more succinate (45.5 mM) than the control.
Biomedical engineering; Chemical engineering