Bacillus thuringiensis: a specific gamma-cyclodextrin producer strain

• B. thuringiensis GU-2 was isolated as a specific γ-cyclodextrin (CD) producing strain.
• The optimum conditions for γ-CD production were estimated to be pH 8.5 and 37 °C.
• A high purity >95% of γ-CD was obtained from starch used as substrate.
• Enzyme activity was estimated at 2.45 U/mL under the optimized condition.

An anaerobic microbial isolate Bacillus species, designated B. thuringiensis GU-2, was isolated from soil as a specific γ-cyclodextrin (CD) producer strain in alkaline medium under anaerobic conditions. The optimum pH and temperature for bacterial growth and γ-CD production were estimated to be pH 8.5 and 37 °C in the presence of 1.0% starch substrate, respectively. A high purity yield >95% of γ-CD from the total CD yield in the reaction mixture was obtained from starch that was supposed to be converted by gamma-cyclodextrin glycotransferase, tentatively named as γ-CGTase. The maximum γ-CGTase activity was estimated at 2.45 U/mL under optimized condition. This is the first report demonstrating the generation of a specific γ-cyclodextrin (CD) producer strain by the action of a γ-CGTase under anaerobic conditions.

A specific gamma-cyclodextrin glycotransferase (γ-CGTase) is attractive for the production of γ-CD. γ-CGTase catalyzes the production of gamma-cyclodextrin from starch via a transglycosylation reaction. The efficiency of transglycosylation reaction was considered in terms of obtaining γ-CD in enzyme reaction of γ-CGTase.Figure optionsDownload as PowerPoint slide