Improving the production of cyclodextrins from the Paenibacillus polymyxa in Bacillus subtilis

The hydrophobic cavity of cyclodextrin contributes to the wide applications in medicine, pharmaceutical, food, cosmetic industries, agriculture and environmental protection. Cyclodextrin glycosyltransferase (cgt) gene was able to be amplified from Paenibacillus polymyxa and inserted into vectors of pWB980. The recombinant vectors were transformed to Bacillus subtilis WB600. The results showed that cgt gene was expressed in Bacillus subtilis successfully. The optimum conditions for maximum enzyme activity were obtained at a temperature 35°C, pH 7 and quantity of inoculum 6%. Corn starch and soybean meal were chosen as carbon source and nitrogen source in the process of production. A maximum activity of the CGTase activity reached 9.2 U/mL, which is about 15-fold to that of the original strain Paenibacillus polymyxa. β-cyclodextrin is 0.104 mg/mL from 1% (m/m) soluble starch in 10 min (pH 7.0 50 oC). Cyclodextrins can form inclusion complexes with different molecules with the aid of their special chemical (molecular) structures. Physical and chemical properties of molecules can be changed after the formation of complex. This special feature enables the usage of cyclodextrins in different industry areas.