CONVENTIONAL PRODUCTION OPTIMIZATION OF CYCLODEXTRIN GLUCOSYL TRANSFERASE BY A NOVEL ISOLATE OF BACILLUS SP. PBS1 FROM POTATO RHIZOSPHERE

Abstract

The cyclodextrin glucosyltransferase enzyme (CGTase) is an industrially crucial enzyme for the production of β-cyclodextrin (β-CD). CGTase has a high propensity to produce a mixture of cyclodextrins (CDs). From the industrial perspective, a CGTase that produces only one type of CD is of critical importance. Bacillus sp. PBS1 produced CGTase that converts starch solely into β-CD. The isolated strain PBS1 was found to close similarity with alkaliphilic Bacillus sp. based on biochemical, morphological, and phylogenetic analysis of its 16s rRNA gene sequencing. The selection and optimization of media ingredients are warranted for the best possible production of β-CD. These steps were carried out by conventional optimization strategies. The presence of glucose, maltose, lactose, sucrose, galactose, mannitol, nitrates, urea, metal salts, and K₂HPO₄ led to the suppression of CGTase production. The improved enzyme production was observed in peptone, soluble starch, magnesium sulfate, and Na₂CO₃. The organism produces maximum CGTase (93.42 ± 2.4 U/ml) at 96-hour incubation in the optimized production medium containing 8% starch, 2% peptone, 0.06% MgSO₄.7H₂O, 0.5% Na₂CO₃, and having pH of 9.3. The optimization of the medium led to ~16% improvement in CGTase production by Bacillus sp. PBS1.