Studies on Preparation of β-Cyclodextrin Production Using Bacillus stearothermophilus β-Cyclodextrin Glycosyltransferase and Reaction Conditions Optimization

Abstract:

Previously，a recombinant Brevibacillus sp. producing the Bacillus stearothermophilus cyclodextrin glycosyltransferase was constructed. In this study，the strain was cultured in shake flask for 48 h，it showed that the highest extracellular enzyme activity was 49 U/mL. The supernatant of the medium was used as crude enzyme for the production of β-cyclodextrin. Then the reaction conditions，such as initial pH，reaction temperature，starch concentration，CGTase dosage，pullulanase dosage and reaction time，on the yields of β-cyclodextrin was investigated. The optimized conditions for the conversion as the following：the initial pH was 6.0，the reaction temperature was 50 ℃，initial starch concentration was 150 g/L ，CGTase concentration was 13 U/mL，pullulanase concentration was 50 U/g starch. Under this conditions，the reaction was continued for 18 h，thecyclodextrin yield is 81.4% and the proportion of β-cyclodextrin is 97.7%.