Effects of acetyl CoA synthetase and citrate synthase on pyruvate producing strains of Escherichia coli

by (Geoffrey Myron), 1978- Smith

Escherichia coli ALS 929 (YYC 202 (Hfr zbi::Tn10 poxB1 ?(aceEF) rpsL pps-4 pfl-1) ldhA) requires acetate to sustain cell growth due to the deletion in several biochemical pathways associated with pyruvate. The accumulation of pyruvate and the consumption of acetate of this strain were examined in a series of batch and continuous fermentations. Acetyl Coenzyme A Synthetase (ACS) from E. coli, which catalyzes the conversion of acetate to acetyl CoA, was overexpressed in ALS 929 to examine the effect of increased acetate utilization on cell growth and pyruvate production. The overexpression of ACS in ALS 929 was also investigated in both batch and continuous culture fermentations. Results have shown that the presence of overexpressed ACS resulted in a higher acetate consumption rate, and a reduced maximum cell concentration. Citrate Synthase (CS) from Bacillus subtilis, which catalyzes the condensation of acetyl CoA and oxaloacetate to citrate, was also investigated.