Strategies for efficient extracellular secretion of recombinant cyclomaltodextrinase by Escherichia coli  

作　　者：Luhua Zheng Bo Jiang Jingjing Chen Licheng Zhou Tao Zhang 

机构地区：[1]State Key Laboratory of Food Science and Technology,Jiangnan University,Wuxi,Jiangsu,214122,China [2]International Joint Laboratory on Food Safety,Jiangnan University,Wuxi,Jiangsu,214122,China

出　　处：《Food Bioscience》2022年第6期1980-1987,共8页食品生物科学（英文）

基　　金：supported by the National Natural Science Foundation of China[grant number 31871745];Major Science and Technology Innovation Project of Shandong Province[grant number 2020CXGC010601].

摘　　要：Cyclomaltodextrinase (CDase, EC 3.2.1.54) is used in the preparation of maltooligosaccharides with a specific degree of polymerization by hydrolyzing cyclodextrins. Extracellular secretion of CDase is beneficial in promoting its application potential. However, a major barrier is that proteins are difficult to cross the inner and outer membranes of cells. Herein, we made an effort to increase the permeability of cell membrane by the deletion of lipopolysaccharide synthesis-related gene (lpxM ). In addition, glycine and Ca^(2+) assisted in the extracellular secretion of recombinant CDase from Bacillus sphaericus E−244. The extracellular fermentation activity of CDase was 2.88 U/mL when ΔycjM -ΔmalS -ΔlpxM was cultured with 1 mM glycine and 5 mM Ca^(2+) for 20 h, accounting for 78.67% of the total fermentation activity, which was 6.26-fold and 6.45-fold higher than that of the parent strain, respectively. Glycine increased cell lysis and disrupted cell morphology, and Ca^(2+) repaired glycine-induced cell growth inhibition. Significantly, deletion of lpxM replaced the use of glycine to a considerable extent, and half the CDase extracellular secretion time.

关 键 词：Extracellular secretion Cyclomaltodextrinase Gene deletion LIPOPOLYSACCHARIDE 

分 类 号：TS201.3[轻工技术与工程—食品科学]