Effect of culture operating conditions on succinate production in a multiphase fed-batch bioreactor using an engineered <Emphasis Type="BoldItalic">Escherichia coli</Emphasis> strain |
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Authors: | Jiangfeng Zhu Chandresh Thakker Ka-Yiu San George Bennett |
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Institution: | (1) Department of Bioengineering, Rice University, Houston, USA;(2) Department of Biochemistry and Cell Biology, MS-140, Rice University, 6100 Main Street, Houston, TX77005-1892, USA;(3) Department of Chemical and Biomolecular Engineering, Rice University, Houston, USA;(4) Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China;(5) Key Laboratory of Biofuels, Chinese Academy of Sciences, Qingdao, China; |
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Abstract: | A metabolically engineered Escherichia coli strain SBS550MG (pHL413) was used in this study to investigate the impact of various culture operating conditions for improving
the specific succinate production rate for better final titer while maintaining the theoretical succinate yield on glucose
in multiphase fed-batch cultures. Previously, we reported that changes in the level of aeration during the cell growth phase
significantly modified gene expression profiles and metabolic fluxes in this system (Martinez et al. 2010). Based on these observations, the examination of culture conditions was mainly focused on the aerobic growth phase. It was
found that 2–5 h of low dissolved oxygen culture during the aerobic phase improves cell productivity, but pH control during
the aerobic phase was not favorable for the system. Cell viability has been identified as a major limiting factor for succinate
production. Supplementing LB medium and betaine, an anti-osmotic stress reagent, did not improve cell activity. A higher succinate
titer (537.8 mM) using the current metabolic engineering E. coli strain was achieved, which can potentially be improved further by increasing cell viability. |
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