Statistical optimization of cyclodextrin glycosyltransferase (CGTase) production from Bacillus macerans in batch cultivation and its purification

Abstract

Cyclodextrin glycosyltransferase (CGTase) catalyzes the formation of Cyclodextrins from starch by an intramolecular transglycosylation reaction. In the present study, the CGTase enzyme was produced from Bacillus macerans NCIM 2131, using shake flask fermentation. Soluble starch and yeast extract were screened as the best carbon and nitrogen source at an individual factor level for enhancing CGTase activity. Similarly, ferrous ion and arginine were found to activate CGTase production in comparison to various other trace metals and amino acids tested. The synergistic effect of individual parameters of CGTase activity and process optimization of cultural condition was performed by response surface methodology (RSM). The optimized media comprised 24 g/L soluble starch; 32.5 g/L ferrous ion, and 15.0 g/L arginine with CGTase activity of 24.23 IU/mL. The final CGTase activity was very close to the predicted value of 24.82 IU/mL with 97.0% validation. Shake flask optimized conditions were further scaled up to 7.5 L fermenter (working volume: 3.0 L) which gave 2.6 folds (64.3 IU/mL) increase in enzyme activity. The enzyme was partially purified by ammonium sulfate precipitation and scanning electronic microscopy (SEM) was used to study the qualitative properties of produced enzyme.