Immobilized Cells of Bacillus circulans ATCC 21783 on Palm Curtain for Fermentation in 5 L Fermentation Tanks.

Jinpeng Wang,Haoran Fan,Chao Qiu,Aiquan Jiao,Xueming Xu,Zhengyu Jin,Yao Hu,Yan Yue

doi:10.3390/molecules23112888

Jinpeng Wang, Haoran Fan + Show 6 more

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https://doi.org/10.3390/molecules23112888

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Abstract

Palm curtain was selected as carrier to immobilize Bacillus circulans ATCC 21783 to produce β-cyclodextrin (β-CD). The influence for immobilization to CGTase activity was analyzed to determine the operation stability. 83.5% cyclodextrin glycosyltransferases (CGTase) of the 1st cycle could be produced in the 7th cycle for immobilized cells, while only 28.90% CGTase was produced with free cells. When palm curtain immobilized cells were reused at the 2th cycle, enzyme activities were increased from 5003 to 5132 U/mL, which was mainly due to physical adsorption of cells on palm curtain with special concave surface structure. Furthermore, conditions for expanded culture of immobilized cells in a 5 L fermentation tank were optimized through specific rotation speed procedure (from 350 r/min to 450 r/min with step size of 50 r/min) and fixed ventilation capacity (4.5 L/min), relations between biomass, enzyme activity, pH, and oxygen dissolution was investigated, and the fermentation periods under the two conditions were both 4 h shorter. Compared with free cell, immobilized cell was more stable, effective, and had better application potential in industries.

Highlights

Bacillus circulans ATCC 21783 was separated from 600 strains with high activity and alkali resistance, which produced mainly β-cyclodextrin glycosyltransferases (CGTase) that created mainly β-CD, few γ-CD, and no α-CD [1,2,3,4,5]
We investigated the potential of palm curtain as carriers of Bacillus circulans ATCC 21783
Adsorption is an important method for reversible cell immobilization, which is based on the attachment of cells on the surface of carrier via electrostatics, hydrophobic interactions, Van der Waals forces, or hydrogen bonds [11]

Summary

Introduction

Bacillus circulans ATCC 21783 was separated from 600 strains with high activity and alkali resistance (pH 10.0), which produced mainly β-CGTase that created mainly β-CD, few γ-CD, and no α-CD [1,2,3,4,5]. Immobilization methods could be classified into irreversible immobilizations such as entrapment, covalent binding, and aggregation, and reversible immobilization methods such as ionic binding, adsorption, metal binding, and affinity binding [9,10,11]. Among these methods, physical adsorption is considered as an excellent potential technique due to its nonnegligible advantages (prolonged and repeated use, ease of separation from the fermentation medium, and less contamination caused) [12,13,14].

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