Preparation of γ-CGTase Mutant and Optimization of the Production of γ-CD

Abstract:

In this thesis，tyrosine 211 of γ-CGTase from Bacillus sp. G-825-6 changed into leucine based on site-directed mutagenesis. The influences of substrate type，concentration，time，temperature，and enzyme concentration on the mutant Y211L catalyticed starch to produced γ-CD were evaluated. On the basis of single of factor experiments，orthogonal design method was used to optimize the condition for production of γ-CD. As a result，the best condition was：cassava starch 6%，enzyme concentration 4 u/g，temperature 50 ℃，time 24 h. Under thses conditions，the production of γ-CD can reach 14%. If the total cyclodextrin content is 100%，the catalytic production ratio of γ-CD is 97%.