On-line detection of acetate formation in Escherichia coli cultures using dissolved oxygen responses to feed transients

• Published in: Biotechnology and bioengineering 1999-09, Vol.64 (5), p.590-598
• Main Authors: Åkesson, Mats, Karlsson, Eva Nordberg, Hagander, Per, Axelsson, Jan Peter, Tocaj, Anita
• Format: Article
• Language: English
• Subjects: acetate; Acetates - metabolism; acetic acid; Batch cell culture; Biological and medical sciences; Bioreactors; Biotechnology; dissolved oxygen; Dissolved oxygen sensors; Escherichia coli; Escherichia coli - genetics; Escherichia coli - metabolism; Fundamental and applied biological sciences. Psychology; Glucose; mathematical model; Mathematical models; Methods. Procedures. Technologies; Microbial engineering. Fermentation and microbial culture technology; Models, Biological; on-line detection; Organic compounds; Oxygen - metabolism; Proteins; Recombinant Proteins - biosynthesis; Recombinant Proteins - genetics; transients
• ISSN: 0006-3592; 1097-0290
• DOI: 10.1002/(SICI)1097-0290(19990905)64:5<590::AID-BIT9>3.0.CO;2-T

Recombinant protein production in Escherichia coli can be significantly reduced by acetate accumulation. It is demonstrated that acetate production can be detected on‐line with a standard dissolved oxygen sensor by superimposing short pulses to the substrate feed rate. Assuming that acetate formation is linked to a respiratory limitation, a model for dissolved oxygen responses to transients in substrate feed rate is derived. The model predicts a clear change in the character of the transient response when acetate formation starts. The predicted effect was verified in fed‐batch cultivations of E. coli TOPP1 and E. coli BL21(DE3), both before and after induction of recombinant protein production. It was also observed that the critical specific glucose uptake rate, at which acetate formation starts, was significantly decreased after induction. On‐line detection of acetate formation with a standard sensor opens up new possibilities for feedback control of substrate feeding. © 1999 John Wiley & Sons, Inc. Biotechnol Bioeng 64: 590–598, 1999.