Two-stage continuous operation of recombinant Escherichia coli using the bacteriophage λ Q- vector

Jeong Seok Oh, Daechul Cho, Tai Hyun Park

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13 Scopus citations


A two-stage continuous culture of Escherichia coli in combination with a bacteriophage λ system was performed in order to overcome the intrinsic plasmid instability that is frequently observed in recombinant fermentation. A phage λ vector with a Q - mutation was used to enhance the expression of the λ system. The optimal values of the important operational variables such as the substrate concentration, the dilution rate, and the mean residence time on the expression of the cloned gene were determined in both batch and continuous cultures. For all culturing modes, the full induction of the cloned gene was observed 4 h after the temperature shift. In the two stage continuous culture, the overproduction reached their maxima at D=0.25 h-1 with 1.5 S 0 of the medium supply. The maximum productivity of the total β-galactosidase was 16.3×106 U l-1 h-1, which was approximately seven times higher than that in the single-copy lysogenic stage. The recombinant cells were stable in the lysogenic state for more than 260 h, while they were stable for 40 h in the lytic state. The instability that developed rapidly in the second tank is believed to be due to the accumulation of lysis proteins as a result of vector leakage during the operation.

Original languageEnglish
Pages (from-to)1-7
Number of pages7
JournalBioprocess and Biosystems Engineering
Issue number1
StatePublished - Dec 2005

Bibliographical note

Funding Information:
Acknowledgments The authors wish to acknowledge the financial support of the Korea Science & Engineering Foundation through the Nano Bio-Electronic & System Center, Seoul National University, Seoul, Korea.


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