Continuous culture of a recombinantEscherichia coli and plasmid maintenance for tryptophan production |
| |
Authors: | Soo W. Nam Byong K. Kim Kwang H. Son Jung H. Kim |
| |
Affiliation: | (1) Department of Biological Science and Engineering, Korea Advanced Institute of Science and Technology, Chongryang, P.O. Box 150, 131 Seoul, Korea |
| |
Abstract: | Summary Production of tryptophan by a temperature sensitive recombinant microorganism (Escherichia coli W3110 trpLDtrpRtstna– (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. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|