A genetically modified Bacillus subtilis strain has been transformed with an optimized vector, mainly for producing a D-psicose 3-epimerase.

The present invention relates to isolated polypeptides having D-psicose 3-epimerase activity and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.

Disclosed herein are methods of producing hexoses from saccharides by enzymatic processes. The methods utilize fructose 6-phosphate and at least one enzymatic step to convert it to a hexose.

An embodiment of the present disclosure provides an apparatus for immobilizing a microbial cell, the apparatus including: a mixing tank in which a cell-carrier-containing mixed solution is accommodated; a nozzle part through which the cell-carrier-containing mixed solution is injected from the mixing tank and is discharged to the outside; and a reaction tank in which a cell immobilized bead is formed by contact between the cell-carrier-containing mixed solution discharged from the nozzle part and an aqueous curing agent solution. In the apparatus for immobilizing a microbial cell according to the present disclosure, since the cell-carrier-containing mixed solution is injected through an air spraying nozzle, even when an immobilized carrier solution having a high viscosity is used, a microbial cell immobilized bead having a small size and having a spherical shape, or an almost spherical shape may be mass-produced.

The invention relates to immobilized enzyme compositions for the preparation of a hexose. Hexoses include, for example, tagatose, psicose, fructose, allose, mannose, galactose, altrose, talose, sorbose, gulose, idose, and inositol. The invention also relates to an enzymatic process for preparing a hexose from a saccharide by contacting a starch derivative with an immobilized enzyme composition of the invention.

Provided are a composition for preparing D-psicose comprising a microorganism of the genus Kaistia, and a method for preparing D-psicose using the same.

The present invention relates to isolated polypeptides having D-psicose 3-epimerase activity and polynucleotides encoding the polypeptides. The invention also relates to nucleic acid constructs, vectors, and host cells comprising the polynucleotides as well as methods of producing and using the polypeptides.

The current disclosure provides a process for enzymatically converting a saccharide into allulose. The invention also relates to a process for preparing allulose where the process involves converting fructose 6-phosphate (F6P) to allulose 6-phosphate (A6P), catalyzed by allulose 6-phosphate 3-epimerase (A6PE), and converting the A6P to allulose, catalyzed by allulose 6-phosphate phosphatase (A6PP).

An object of the present invention is to provide a rare sugar-containing composition having improved properties as a sweetener while maintaining the excellent functionality of D-psicose. The invention relates to a method of producing a rare-sugar containing composition with D-fructose as a raw material. An intended product having a novel composition of D-glucose, D-fructose, and D-psicose is obtained by preparing a mixture of D-fructose and D-psicose by using ketose 3-epimerase in the first stage and converting D-fructose into D-glucose by using D-xylose isomerase inert to D-psicose in the second stage. The first-stage product is a mixture of D-fructose and rare sugar D-psicose. The resulting mixture is a sweetener having a taste quality equal to that of sugar.

A method for preparing high-purity D-psicose, comprising the following steps: (1) centrifuging a fermentation broth of Bacillus subtilis, and then subjecting the bacteria to homogenization to obtain a mixed solution containing D-psicose 3-epimerase; (2) preparing a fructose solution, adding the mixed solution containing D-psicose 3-epimerase to the fructose solution, adjusting the pH, adding cobalt chloride thereto, and performing the reaction at a certain temperature; and feeding the fructose solution to the reaction solution, continuing the reaction, and stopping the reaction, obtaining a crude D-psicose solution; and (3) subjecting the crude D-psicose solution to decolorization, filtration, ion exchange, chromatographic separation, concentration, and then crystallization or drying, obtaining D-psicose.