Change of extracellular cAMP concentration is a sensitive reporter for bacterial fitness in high-cell-density cultures of Escherichia coli
2004 (English)In: Biotechnology and Bioengineering, ISSN 0006-3592, E-ISSN 1097-0290, Vol. 87, no 5, 602-613 p.Article in journal (Refereed) Published
Guanosine-3'5'-tetraphosphate (ppGpp) and as, two regulators of the starvation response of Escherichia coli, have received increasing attention for monitoring cell physiological changes in production processes, although both are difficult to quantify. The kinetics of cAMP formation and degradation were not yet investigated in such processes, although the complex regulation of cAMP by synthesis, release, and degradation in connection with straightforward methods for analysis renders it a highly informative target. Therefore, we followed the cAMP concentration in various nonrecombinant and in four different recombinant glucose-limited fed-batch processes in different production scales. The intracellular cAMP concentration increases strongly at the end of the batch phase. Most cAMP is released to the cultivation medium. The rates of accumulation and degradation of extracellular cAMP are growth-rate-dependent and show a distinct maximum at a growth rate of about 0.35 h(-1). At very low growth rates, below 0.05 h(-1), extracellular cAMP is not produced but rather degraded, independent of whether this low growth rate is caused by glucose limitation or by the high metabolic load of recombinant protein production. In contrast to intracellular cAMP, which is highly unstable, analysis of extracellular cAMP is simpler and the kinetics of accumulation and degradation reflect well the physiological situation, including unlimited growth, limitation, and severe starvation of a production host.
Place, publisher, year, edition, pages
2004. Vol. 87, no 5, 602-613 p.
cAMP, RpoS, ppGpp, fed-batch cultivation, recombinant protein production, E. coli, recombinant protein-production, fibroblast-growth-factor, multiparameter flow-cytometry, fed-batch fermentations, limited fed-batch, cyclic-amp, metabolic adaptation, heterologous gene, synthesis rates, rna-polymerase
IdentifiersURN: urn:nbn:se:kth:diva-23670DOI: 10.1002/bir.20152ISI: 000223500700005ScopusID: 2-s2.0-4644340454OAI: oai:DiVA.org:kth-23670DiVA: diva2:342369
QC 20100525 QC 201109162010-08-102010-08-102011-09-16Bibliographically approved