Production of cyclodextrin glucanotransferase from alkalophilic Bacillus sp. TS1-1: Optimization of carbon and nitrogen concentration in the feed medium using central composite design

摘要

Optimisation of nutrient feeding was developed to overcome the limitation in batch fermentation and to increase the CGTase production fromudBacillus sp. TS1-1 in fed batch fermentation. Optimisation of the C/N ratio in the feed stream was conducted in a 5 l fermenter, where feeding wasudinitiated at constant rate of 0.02 h−1. In our initial screening process, the addition of nitrogen source boosted the growth of the microbes, but on theudother hand reduced the CGTase production. The amount of tapioca starch and yeast extract was optimised in order to obtain a sufficient growth andudthus, increased the CGTase production. Results were analysed using three-dimensional response surface plot, and the optimised values of carbonudand nitrogen concentration of 3.30% (w/v) and 0.13% (w/v) were obtained, respectively. CGTase activity increased up to 80.12 U/ml, which isud13.94% higher as compared to batch fermentation (70.32 U/ml). This also led to 14.54% increment of CGTase production in fed batch culture asudcompared to the production before the optimisation. The CGTase activity obtained was close to the predicted value, which is 78.05 U/ml.ud© 2006 Elsevier B.V. All rights reserved.udKeywords: Cyclodextrin glucanotransferase; C/N ratio; Fed batch; Central composite design