Efficient production of D-HPG with an immobilized transgenic strain E. coli LY13-05
2015
Hu, Xiaobing | Lin, Biaosheng
The aim of the present study was to construct a recombinant strain of Escherichia coli LY13-05 that simultaneously expresses D-hydantoinase (Dhase) and D-decarbamoylase (Dcase) and exhibits a high-efficiency substrate conversion with a specific yield rate, close to those reported in the literature for other bacteria. The cultivation conditions, fermentation properties and immobilized recombinant strain performance were investigated. The results indicated that E. coli LY13-05 cultured in Terrific Broth (TB) medium containing 1% lactose and induced at 22 °C revealed the strongest total Dhase/Dcase activity. A fermentation with 30 g/L DL-p-hydroxyphenyl hydantoin (DL-HPH) as the substrate was conducted for 12 h using the immobilized strain. The cell density in the broth reached up to 1.9 g/L; the yield of D-HPG was 29.10 g/L; the yield of D-p-hydroxyphenylglycine (D-HPG)/HPH was 97.0%; the specific productivity was 1.276 g/g h and the productivity was 2.43 g/L h. The immobilized strain exhibited certain advantages in substrate conversion efficiency during the production of D-HPG and the specific yield rate, which were close to or better than the yield of D-HPG from other reported strains. Also, compared with the free cells, the immobilized E. coli LY13-05 cells had higher conversion efficiency and yield. Moreover, the immobilized strains had better thermal stability, higher repetition application time and longer storage duration, which will be more practical for industrial production.
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