title: Production of d-allulose from d-glucose by Escherichia coli transformant cells co-expressing d-glucose isomerase and d-psicose 3-epimerase genes.
abstract: BACKGROUND
  d-Allulose is a novel and low-calorie rare monosaccharide that is a C-3 epimer of d-fructose. Because of its excellent physiological properties and commercial potential, d-allulose has attracted researchers' interests. Based on the Izumoring strategy, d-allulose is converted from d-fructose by d-psicose 3-epimerase (DPEase), while d-fructose is converted from d-glucose by d-glucose isomerase (GIase). In this study, we created a cellular system capable of converting d-glucose to d-allulose in a one-step process that co-expressed the GIase from Acidothermus cellulolyticus and the DPEase from Dorea sp. CAG.
  
  
  RESULTS
  The co-expression plasmid pETDuet-Dosp-DPE/Acce-GI was generated and transformed into Escherichia coli BL21(DE3) cells. The recombinant co-expression cells exhibited maximum catalytic activity at pH 6.5 and 75 °C. These cells were thermostable at less than 60 °C. The addition of Co2+significantly increased the catalytic activity by 10.8-fold. When the reaction equilibrium was reached, the ratio of d-glucose, d-fructose and d-allulose was approximately 6.5:7:3, respectively.
  
  
  CONCLUSIONS
  A recombinant co-expression strain that catalysed the bioconversion of d-allulose from d-glucose in a one-step process was created and characterised. When adding 500 g L-1d-glucose as a substrate, 204.3 g L-1d-fructose and 89.1 g L-1d-allulose were produced. © 2016 Society of Chemical Industry.
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Wenli
authors.initials: W
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Wanmeng
authors.initials: W
authors.lastname: Mu
mesh_terms: D039903:Actinobacteria / Q000201:enzymology; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001711:Biotransformation; D000068016:Eubacteriales / Q000201:enzymology; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D005632:Fructose / Q000737:chemistry / Q000378:metabolism*; D015870:Gene Expression; D005947:Glucose / Q000737:chemistry / Q000378:metabolism*; D007536:Isomerism; D060847:Metabolic Engineering; D019998:Racemases and Epimerases / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C003243:psicose; D005632:Fructose; D019998:Racemases and Epimerases; D005947:Glucose
keywords: co-expression; d-allulose; d-glucose isomerase; d-psicose 3-epimerase; rare monosaccharide