Improvement of cyclodextrin glycosyltransferase (CGTase) production by recombinant Escherichia coli pAD26 immobilized on the cotton

The cyclodextrin glycosyltransferase (CGTase) of the recombinants Escherichia coli pAD26 cells immobilized on cotton was optimally produced by statistical methodology. Primarily, carbon and nitrogen sources were selected by one-factor-at-a-time method. Wheat starch, Casamino acid, Edamin and Hy-soy were identified as the best nutrients. These sources were secondly confirmed by Plackett-Burman design (fifteen variables were studied with sixteen experiments), as the most significant components with respect to CGTase production. In the third step, concentration of most significant factors and their interaction were optimized with a Box-Behnken experimental design. Under the optimized conditions (agitation 200 rpm, yeast extract concentration 20 g/L, wheat starch concentration 10 g/L and Hy-soy concentration 2.5 g/L), CGTase yield 145.11 U/mL was 3.6 and 23 folds higher than those obtained by the use of the initial conditions (39.77 U/mL) and free cells (6.37 U/mL), respectively.