Reduction of aerobic acetate production by Escherichia coli.
Acetate excretion by Escherichia coli during aerobic growth on glucose is a major obstacle to enhanced recombinant protein production. We report here that the fraction of carbon flux through the anaplerotic pathways is one of the factors influencing acetate excretion. Flux analysis of E. coli central metabolic pathways predicts that increasing the fraction of carbon flux through the phosphoenolpyruvate carboxylase (PPC) pathway and the glyoxylate bypass reduces acetate production. We tested this prediction by overexpressing PPC and deregulating the glyoxylate bypass by using a fadR strain. Results show that the acetate yield by the fadR strain with PPC overexpression is decreased more than fourfold compared to the control, while the biomass yield is relatively unaffected. Apparently, the fraction of carbon flux through the anaplerotic pathways is one of the factors that influence acetate excretion. These results confirm the prediction of our flux analysis and further suggest that E. coli is not fully optimized for efficient utilization of glucose.
Farmer
W R
WR
Department of Chemical Engineering, Texas A&M University, College Station 77843-3122, USA.
Liao
J C
JC
D000085:Acetates / Q000378:metabolism*; D000332:Aerobiosis; D001426:Bacterial Proteins / Q000235:genetics; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D005947:Glucose / Q000378:metabolism; D006038:Glyoxylates / Q000378:metabolism; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics / Q000378:metabolism; D010957:Plasmids / Q000235:genetics; D019289:Pyruvic Acid / Q000378:metabolism; D011995:Recombination, Genetic; D012097:Repressor Proteins / Q000235:genetics; D013386:Succinates / Q000378:metabolism; D019802:Succinic Acid
D000085:Acetates; D001426:Bacterial Proteins; C057119:FadR protein, Bacteria; D006038:Glyoxylates; D012097:Repressor Proteins; D013386:Succinates; D019289:Pyruvic Acid; D019802:Succinic Acid; D010730:Phosphoenolpyruvate Carboxylase; D005947:Glucose; C031150:glyoxylic acid