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A balanced DO‐stat and its application to the control of acetic acid excretion by recombinant Escherichia coli
Author(s) -
Konstantinov Konstantin,
Kishimoto Michimasa,
Seki Tatsuji,
Yoshida Toshiomi
Publication year - 1990
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260360714
Subject(s) - acetic acid , fermentation , escherichia coli , excretion , biochemistry , yeast , phenylalanine , chemistry , recombinant dna , food science , biology , amino acid , gene
During fed‐batch cultivation of a recombinant Escherichia coli AT2471 harboring plasmid pSY130–14 for phenylalanine production, a large amount of acetic acid was excreted by the cells and accumulated in the culture medium. Acetic acid concentration reached 30–35 g/L at the end of a process conducted without special precautions for the reduction of this excretion. Cell growth stopped when acetic acid concentration was about 15 g/L, resulting in poor growth, 16 g/L cell concentration, and poor production — 8 g/L phenylalanine. A novel control strategy, called a balanced DO‐stat. was developed to prevent acetic acid excretion. It represents a model‐independent two‐loop control structure, which is simple, reliable, and convenient for computer application. Using the balanced DO‐stat, implemented in a computer control system, acetic acid concentration was kept at zero during the entire cultivation period. As a result, the cell concentration increased to 36 g/L and phenylalanine concentration reached 24 g/L. Aside from the phenylalanine fermentation, the proposed control approach might be applied to cultivation of other bacterial and yeast strains which have similar mechanism of the excretion of fermentative by‐products.