D. O'Beirne, B. Glennon, G. Hamer

Recent evaluations concerning industrial biotechnological processes suggest that many such processes will be based on genetically manipulated strains of a very small number of species, with major emphasis on Escherichia coli strains. Accordingly, EU Project No. BIO4-CT95-0028, Bioprocess Scale-up Strategy based on Integration of Microbial Physiology and Fluid Dynamics, of which this research project is a part, employs E. coli W3110 as the process culture.

 Growth theory was developed on the assumption that microorganisms were either obligate aerobes or obligate anaerobes, whereas E. coli is a facultative anaerobe. While the response of obligate aerobes to oxygen limitation can be described by growth theory, the effects of oxygen availability on the growth of E. coli on glucose are much more complex partially because of acetate excretion under aerobic conditions and of formation of products of the mixed acid fermentation under anaerobic conditions.

 The present study is seeking to define the effects of transitions in oxygen availability on both the macro- and molecular-scale responses of the process culture. Emphasis is being placed on the fed-batch mode of operation, but continuous culture experiments will be conducted to elucidate acetate and other product re-utilisation.

Sponsor: EU Framework IV Programme

Collaboration: KTH Stockholm; University of Greifswald; University of Stuttgart; University of Birmingham; Lund University; TU Delft; Telemark Institute of Technology; Pharmacia/Upjohn; Lonza AG; MultiFerm AB; Scaba AB.