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Abstract

For many years understanding of the metabolism of Escherichia coli has been one of the main topics in microbiology research. Phenomena like the glucose effect or the inducer exclusion have been detected and described. It is known that Escherichia coli prefers glucose as carbon- and ammonium salt as nitrogen- source. Older publications describe growth of the wildtype and of mutant strains with limiting or unlimiting concentrations of different carbon- or nitrogen sources. Most of these descriptions are only qualitative. Many details have been elucidated about the regulation of nitrogen and carbon metabolism but little is known about their coordination. Therefore we measured in a systematic way growth rates of Escherichia coli LJ110 under carbon-, nitrogen- or carbon- and nitrogen limiting conditions in batch experiments. The uptake of carbohydrates is regulated by the phosphoenolpyruvate-dependent phosphotransferase systems especially the protein kinase enzyme EIIACrr and the global regulator complex cAMP.CRP. To analyse the connection of carbohydrates and nitrogen control we determined the phosphorylation state of EIIACrr and the levels of extracellular cAMP under the different growth conditions.