Summary
Production of tryptophan by a temperature sensitive recombinant microorganism (Escherichia coli W3110 ΔtrpLDtrpR ts tna − (pCRT185)) was investigated. In a single-stage continous culture, at an elevated temperature, 42°C (derepressed condition), tryptophan concentration increased in an early phase of the fermentation, and then gradually decreased with time. The reduction in the production rate was mostly due to the segregation of the plasmid and subsequent increase of plasmid-free cells. However, the plasmid could be maintained stable at 37°C, with repressed condition oftrp-operon, over 200 generations. A two-stage continuous culture system, i.e. cell growth was maintained in the first stage at 37°C and gene expression was induced in the second stage at 42°C, was therefore tested to improve the performance of the fermentation system. Operation of the two-stage system showed that the plasmid stability was significantly improved, and the specific rate of tryptophan production was maintained almost constant for more than 500 hours in the second stage.
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Dwivedi, C. P., Imanaka, T., and Aiba, S. (1982), Biotechnol. Bioeng.24, 1465–1468.
Helling, R. B., Kinney, T., and Adams, J. (1981), J. Gen. Microbiol.123, 129–141.
Hershfield, V., Boyer, H. W., Yanofsky, C., Lovett, M. W., and Helinski, D. R. (1974), Proc. Natl. Acad. Sci.71, 3455–3459.
Imanaka, T. and Aiba, S. (1981), Ann. N. Y. Acad. Sci.369, 1–14.
Ito, K., Hiraga, S., and Yura, T. (1969), J. Bacteriol.99, 279–286.
Kim, K. T. (1985), Laboratory Report.
Lee, S. B., Seressiotis, A., and Bailey, J. E. (1985), Biotechnol. Bioeng.27, 1699–1709.
Lee, S. Y., Chi, Y. T., and Choi, S. Y. (1985), Korean J. Genet.7, 1–8.
Miller, J. H. (1972), Experiments in Molecular Genetics. Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, 432.
Siegel, R. and Ryu, D. D. Y. (1985), Biotechnol. Bioeng.27, 28–33.
Udenfriend, S. and Peterson, R. E. (1962), Methods in Enzymology3, 613–614.
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Nam, S.W., Kim, B.K., Son, K.H. et al. Continuous culture of a recombinantEscherichia coli and plasmid maintenance for tryptophan production. Biotechnol Lett 9, 489–494 (1987). https://doi.org/10.1007/BF01027458
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DOI: https://doi.org/10.1007/BF01027458