FOOD SCIENCE ›› 2013, Vol. 34 ›› Issue (9): 164-169.doi: 10.7506/spkx1002-6630-201309034

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Immobilization of Cells Producing Glucose Isomerases

DENG Hui1,2,CHEN Sheng1,2,CHEN Jian1,2,WU Jing1,2,*   

  1. 1. State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China;2. Key Laboratory of
    Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
  • Received:2012-09-06 Revised:2013-04-11 Online:2013-05-15 Published:2013-05-07
  • Contact: WU Jing E-mail:jingwu80@hotmail.com

Abstract:

In the present study, immobilization technology of recombinant Escherichia coli cells producing
Thermobifida fusca glucose isomerase was studied using chitosan flocculation and glutaraldehyde cross-linking
methods. In order to obtain the immobilization method for GIase with high performance and low cost, various factors
for affecting flocculation and crosslinking were investigated, and the physical and chemical properties, dynamic
constants and operation stability of immobilized enzyme preparation were determined. The results showed that the
optimal immobilization conditions were diatomaceous earth addition of 0.6% and 5 mmol/L Mg2+ in high-density
fermentation broth. After heat treatment at 60 ℃ for 30 min, cells and debris were flocculated by 0.1‰ chitosan
solution at pH 5.5 under fully rabbling, and recovery rate of GIase reached up to 98%. Flocculation was cross-linked
for 3 h in 0.25% glutaraldehyde solution at pH 6.5 under slight rabbling, and the enzyme activity reached up to 80%
of flocculation. Compared to free GIase, the optimal temperature was 80 ℃, and the optimal pH reduced from 10 to 9.
The initial enzyme activity 356 U/g, and its half-life reached up to 61 d.

Key words: glucose isomerase, recombinant Escherichia coli cells, immobilization, chitosan flocculation, glutaraldehyde cross-linking

CLC Number: