Optimization of Cultivation Conditions for the Production of γ-Cyclodextrin Glucanotransferase by Bacillus macorous

Abstract

The production of γ-cyclodextrin glucanotransferase (γ-CGTase) from Bacillus macorous WSH02-06 was optimized in shake flasks using conventional sequential techniques and statistical experimental design. Effects of nutrients including carbon and nitrogen sources, cation ions, initial pH, and temperature on γ-CGTase production were investigated. Corn starch, peptone, Mn²⁺, and Zn²⁺ were found to be essential for obtaining high γ-CGTase activity and biomass. The promoting effect of manganese and zinc on enzyme production has not been reported previously. According to the results of orthogonal array experiment, the optimal culture medium for high γ-CGTase activity was determined. Maximal γ-CGTase activity obtained in the optimized culture broth was about 250 U/mL which was 10-fold higher than that obtained in the basal medium. Time course of cell growth and γ-CGTase production in a 7 l fermenter showed that enzyme production was growth associated, and that maximum γ-CGTase activity reached 277 U/mL in 17 h.

Acknowledgments

The authors would like to thank Xia Cheng for assistance with the accomplishment of some parts of this study.