Verlag des Forschungszentrums Jülich
JUEL-4199
Veit, Andrea
Untersuchungen zum Überflussmetabolismus in Escherichia coli
112 S., 2006
Characterization of overflow metabolism in Escherichia coli
In biotechnology, recombinant E. coli strains are used for the production of fine chemicals
and heterologous proteins. During aerobic growth on glucose, E. coli produces acetate, a
phenomenon referred to as overflow metabolism. The accumulation of acetate perturbs
growth and recombinant protein production. Until now the molecular cause of aerobic
acetate excretion is not fully understood. Previous work has revealed gene expression
changes correlating with acetate formation. Genes coding for enzymes of both the
tricarboxylic acid cycle and the respiratory chain as well as genes of unknown function (i.e.
gadE, actP, yjcH and yjeJ) showed differential expression. In this work the following results
were obtained:
The constructed strain excreted significantly less acetate than the wild type while
maintaining high glucose uptake rates. The reduced acetate formation was not
accompanied by the formation of other incomplete oxidation products. Instead the
formation of carbon dioxide increased as a likely consequence of elevated TCA cycle
activity which accounts for the diminished acetate overflow. So aerobic acetate
formation is primarily caused by transcriptional control of the sdhCDAB- b0725-
sucABCD operon.
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