Optimization of Induction Conditions for Bacillus-derived Esterase Production by High-cell Density Fermentation of Recombinant Escherichia coli
2017
Kang, S.H., Inha University, Incheon, Republic of Korea | Min, B.H., Inha University, Incheon, Republic of Korea | Choi, H.Y., Inha University, Incheon, Republic of Korea | Kim, D.I., Inha University, Incheon, Republic of Korea
To increase the efficiency of esterase production by Bacillus, high cell-density culture of recombinant Escherichia coli through fed batch fermentation was tested. Cells were cultured to OD∧600 of 76 (35.8 g/l DCW) with dissolved oxygen level controlled to least above 30% air saturation by supplying pure oxygen. Cells were cultured to an OD∧600 of 90 (42.4 g/l DCW) with glucose feeding controlled to at least 1 g/l. However, the cells reached stationary phase at the late stage of culture, despite glucose being supplied. Cells were cultured to an OD∧600 of 185 (87.3 g/l DCW) by supplying additional medium with fortified yeast extract. To increase the productivity of the recombinant protein, cell growth and esterase productivity based on induction time were evaluated. Late exponential phase induction for esterase production in fed batch fermentation resulted in maximum optical density OD∧600 of 190 (89 g/l DCW) and maximum esterase activity of 1745 U/l, corresponding to a 5.8-fold enhancement in esterase production, compared to the early exponential phase induction. In this study, we established fermentation methods for achieving maximum production of Bacillus-derived esterase by optimizing IPTG induction time in high-cell density culture by supplying pure oxygen and a nitrogen source.
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