A Novel Glucose Isomerase from Caldicellulosiruptor bescii with Great Potentials in the Production of High-Fructose Corn Syrup.

Chenxia Dai,Yunyi Xiao,Hulin Qiu,Ying Li,Junren Zhao,Tingting Miao,Bo Xu,Jinping Hai

doi:10.1155/2020/1871934

Abstract

Glucose isomerase (GI) that catalyzes the conversion of D-glucose to D-fructose is one of the most important industrial enzymes for the production of high-fructose corn syrup (HFCS). In this study, a novel GI (CbGI) was cloned from Caldicellulosiruptor bescii and expressed in Escherichia coli. The purified recombinant CbGI (rCbGI) showed neutral and thermophilic properties. It had optimal activities at pH 7.0 and 80°C and retained stability at 85°C. In comparison with other reported GIs, rCbGI exhibited higher substrate affinity (Km = 42.61 mM) and greater conversion efficiency (up to 57.3% with 3M D-glucose as the substrate). The high catalytic efficiency and affinity of this CbGI is much valuable for the cost-effective production of HFCS.

Highlights

Glucose isomerase (GI), known as xylose isomerase, catalyzes the reversible isomerization of D-xylose and D-glucose to D-xylulose and D-fructose, respectively
GI is widely used in the industrial production of highfructose corn syrup (HFCS) [1], which is a mixture of glucose and fructose and has the advantages of sweetness, low cost, and high solubility [2]
According to the fructose content, HFCS is divided into three types: HFCS-42 (42% fructose, 53% glucose, and 5% polysaccharide), HFCS-55 (55% fructose, 42% glucose, and 3% polysaccharide), and HFCS-90 (90% fructose, 9% glucose, and 1% polysaccharide) [3]

Summary

Introduction

Glucose isomerase (GI), known as xylose isomerase, catalyzes the reversible isomerization of D-xylose and D-glucose to D-xylulose and D-fructose, respectively. GI is widely used in the industrial production of highfructose corn syrup (HFCS) [1], which is a mixture of glucose and fructose and has the advantages of sweetness, low cost, and high solubility [2]. Along with the increase of reaction temperature, the conversion rate of glucose to fructose gradually increases. Thermostable GI is more favorable for the one-step production of HFCS-55 If this thermostable GI can convert high concentrations of glucose to fructose at a higher rate, it would be remarkable for industrial purposes [1]. The enzyme showed the highest conversion rate of 57.3% with 3M D-glucose It has great application potentials in the industrial production of HFCS-55

Materials and Methods

Results and Discussion

Conclusions

Conflicts of Interest