Regulation of CCR in the γ-CGTase production from Bacillus macorous by the specific cell growth rate control

Malto-oligosaccharides were products of the degradation of corn starch in the γ-CGTase production by Bacillus macorous WSH02-06, and catabolically repressed the synthesis of γ-CGTase. The investigation of the enzyme production at different agitation speeds, pH-stat values and temperatures revealed that the amount of malto-oligosaccharides accumulated in cultivation was in direct connection with the specific cell growth rate. When the maximal specific growth rate was higher than 0.2 h−1, the γ-CGTase yield decreased. Thus, the nutrients were supplied in the exponential feeding mode for limiting the maximal specific growth rate and the γ-CGTase yield was promoted to the highest value of 2565 U mL−1 that was 6.88-fold higher than that achieved in the batch fermentation.