Fed-batch Fermentations of Recombinant Escherichia coli to Produce Bacillus macerans CGTase

  • Park, Yong-Cheol (Interdisciplinary Program of Biochemical Engineering, Seoul National University) ;
  • Kim, Chang-Sup (Department of Food Science and Technology, Research Center for New-Biomaterials in Agriculture, Seoul National University) ;
  • Kim, Chung-Im (Department of Food Science and Technology, Research Center for New-Biomaterials in Agriculture, Seoul National University) ;
  • Choi, Kyu-Hwan (Biotechnology Laboratory, Jinro Central Research Institute) ;
  • Seo, Jin-Ho (Interdisciplinary Program of Biochemical Engineering, Seoul National University)
  • 발행 : 1997.10.01

초록

The recombinant Escherichia coli BL21(DE3)pLysE : pTCGT1 was grown to overproduce Bacillus macerans cyclodextrin glucanotransferase (CGTase) able to synthesize ${\alpha}$-cyclodextrin (CD) with a selectivity of 67%. A number of batch fermentations were performed to test the possibility of using lactose as an inducer of the E. coli T7 promoter system. A mixture of isopropyl ${\beta}$-D-thiogalactoside (IPTG) and lactose (1 : 1) gave a maximum CGTase activity of 2.4 U/ml, which was higher than the value obtained with induction by IPTG alone. Fed-batch fermentations involving a glucose-controlled growth period followed by a gene-expression phase with mixtures of IPTG and lactose were employed to achieve high cell density and thereby increase total CGTase activity. Optimized fed-batch fermentation using the modified inducer (IPTG : lactose=1 : 3) and 100 g/l yeast extract solution in the gene-expression phase resulted in a maximum CGTase activity of 62.9 U/ml and a final cell mass of 53.5 g/l, corresponding to a 31-fold increase in CGTase activity and a 29-fold increase in cell mass compared with the control batch fermentation.

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