Respirometric evaluation and modeling of glucose utilization by Escherichia coli under aerobic and mesophilic cultivation conditions

• Published in: Biotechnology and bioengineering Vol. 96; no. 1; pp. 94 - 105
• Main Authors: Insel, G., Celikyilmaz, G., Ucisik-Akkaya, E., Yesiladali, K., Cakar, Z.P., Tamerler, C., Orhon, D.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.01.2007; Wiley
• Subjects: acetate generation; Acetates - metabolism; Aerobiosis - physiology; Biological and medical sciences; Bioreactors - microbiology; Biotechnology; Cell Culture Techniques - methods; Cell Proliferation; Computer Simulation; culture history; Escherichia coli; Escherichia coli - physiology; Fundamental and applied biological sciences. Psychology; Glucose - metabolism; glycogen formation; growth kinetics; Hot Temperature; Kinetics; Metabolic Clearance Rate; metabolic products; Models, Biological; Oxygen - metabolism; Oxygen Consumption - physiology; sequencing batch reactor; Temperature; metabolic products; Growth; Glycogen; Escherichia coli; Respirometry; growth kinetics; acetate generation; Acetate; Aerobe; Glucose; Metabolism; glycogen formation; Modeling; Bioreactor; Sequencing batch reactor; Mesophily; Bacteria; Kinetics; Culture; culture history; Enterobacteriaceae
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/bit.21163

The study presents a mechanistic model for the evaluation of glucose utilization by Escherichia coli under aerobic and mesophilic growth conditions. In the first step, the experimental data was derived from batch respirometric experiments conducted at 37°C, using two different initial substrate to microorganism (S0/X0) ratios of 15.0 and 1.3 mgCOD/mgSS. Acetate generation, glycogen formation and oxygen uptake rate profile were monitored together with glucose uptake and biomass increase throughout the experiments. The oxygen uptake rate (OUR) exhibited a typical profile accounting for growth on glucose, acetate and glycogen. No acetate formation (overflow) was detected at low initial S0/X0 ratio. In the second step, the effect of culture history developed under long‐term growth limiting conditions on the kinetics of glucose utilization by the same culture was evaluated in a sequencing batch reactor (SBR). The system was operated at cyclic steady state with a constant mean cell residence time of 5 days. The kinetic response of E.coli culture was followed by similar measurements within a complete cycle. Model calibration for the SBR system showed that E. coli culture regulated its growth metabolism by decreasing the maximum growth rate (lower $\hat {\mu} _{\rm H}$) together with an increase of substrate affinity (lower KS) as compared to uncontrolled growth conditions. The continuous low rate operation of SBR system induced a significant biochemical substrate storage capability as glycogen in parallel to growth, which persisted throughout the operation. The acetate overflow was observed again as an important mechanism to be accounted for in the evaluation of process kinetics. Biotechnol. Bioeng. 2007;96: 94–105. © 2006 Wiley Periodicals, Inc.