Biosynthesis of cyclodextrin glucosyltransferase by the free and immobilized cells of Bacillus cereus NRC7 in batch and continuous cultures

Abstract

Aims: The objective of this study was to enhance the production of cyclodextrin glucanotransferase (CGTase) produced by a local isolate Bacillus cereus NRC7. Methods and Results: In batch culture, maximal CGTase activity (69·0 U ml−1) was reached after 24‐h incubation period. In continuous production of CGTase by the free cells of B. cereus NRC7, maximal reactor productivity (11·76 KU l−1 h−1), with enzyme concentration of 49·0 U ml−1 and specific productivity of 904·6 U per g wet cells per h, was attained at dilution rate of 0·24 h−1, over a period of 640 h. Bacillus cereus NRC7 cells were immobilized on chitosan. The immobilization conditions with respect to matrix concentration and maximal cell loading were optimized for maximal CGTase production. In repeated batch operation, the activity of the immobilized cells was stable during ten cycles and the activity remained between 51 and 55 U ml−1. In packed‐bed reactor, the immobilized cells showed maximal productivity (27·18 KU l−1 h−1) with enzyme concentration of 54·63 U ml−1 and specific productivity of 151·89 U per g wet cells per h at dilution rate of 0·5 h−1. The half‐life of the immobilized cells was higher than 20 days. Conclusions: Continuous fermentation by the immobilized cells in packed‐bed reactor is an appropriate potential technique for B. cereus NRC7 CGTase production that gave maximum productivity (27·18 KU l−1 h−1), which was 9·47‐, 2·31‐, 12·24‐ and 12·94‐fold higher than the free cells in batch, free cells in continuous, immobilized cells in batch and repeated batch cultures, respectively. Significance and Impact of the Study: This is the first study that evaluates CGTase productivity, in different fermentation modes, in terms of specific productivity (U per gram cells per h). In continuous fermentation by immobilized cells, maximal levels of CGTase productivity are higher than the previously reported values.

Production and characterization of β‐cyclodextrin glucanotransferase fromBacillus sp. ND1

“…On the basis of the number of glucopyranose units, cyclodextrins are classified mainly into three types, known as α, β, and γ, having six, seven, and eight glucopyranose units, respectively . Cyclodextrin can form inclusion complexes with various organic and inorganic compounds due to their cyclic structure . The binding of guest molecules with cyclodextrins can modify the chemical reactivity, solubility, stability, odor, and color of the guest molecules.…”

Inhibitory effect of α-cyclodextrin on α-amylase activity

“…A = M/0.01 ………….. (1) where A (U/mL) is the activity of α-amylase and M (μmol) is the amount of maltose produced under the action of α-amylase. The relative residual activity (RRA) was defined as the ratio of the activity of the α-amylase when α-CD was added and α-amylase activity without the addition of α-CD [11].…”

“…Cyclodextrins (CDs) consists of α-D-glucose units linked by α-(1,4)-glucosidic bond, which can form a clathrate with a variety of substances because of its hydrophobic cavity [1]. CDs includes three types of CDs (α-, β-, γ-), which have the same cavity height but differ in size and volume that leads to their different properties [2].…”

pH and redox-operated nanovalve for size-selective cargo delivery on hollow mesoporous silica spheres

“…β-cyclodextrin is cyclic oligosaccharides containing seven glucose units. It has a hydrophobic and nonpolar cavity to form inclusion complexes with a range of guests [43][44][45].…”