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Lookup NU author(s): Dr Ronan O'Kennedy
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The presence of a plasmid, containing gene sequences for DNA immunotherapy that are not expressed in microbial culture, imposed a degradation in bioreactor performance in cultures of the host E. coli strain. Significant decreases in growth rate (24%) and biomass yield (7%) and a corresponding increase in overflow metabolism were observed in a strain containing a therapeutic sequence (a hepatitis B antigen under the control of a CMV promotor). The observed increase in overflow metabolism was incorporated into a Metabolic Flux Analysis (MFA) model (as acetate secretion). Metabolic flux analysis revealed an increase in TCA cycle flux, consistent with an increased respiration rate observed in plasmid-containing cells. These effects are thought to result from increased ATP synthesis requirements (24%) arising from the expression of the Kanr plasmid marker gene whose product accounted for 18% of the cell protein of the plasmid-containing strain. These factors will necessitate significantly higher aeration and agitation rates or lower nutrient feed rates in high-density cultures than would be expected for plasmid-free cultures.
Author(s): Rozkov A, Avignone-Rossa CA, Ertl PF, Goryanin II, Jones P, O'Kennedy RD, Smith JJ, Dale JW, Bushell ME
Publication type: Article
Publication status: Published
Journal: Biotechnology and Bioengineering
Year: 2004
Volume: 88
Issue: 7
Pages: 909-915
ISSN (print): 0006-3592
ISSN (electronic): 1097-0290
Publisher: John Wiley & Sons, Inc.
URL: http://dx.doi.org/10.1002/bit.20327
DOI: 10.1002/bit.20327
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