Disclosed herein are improved processes for making tagatose including the steps of converting F6P to T6P, catalyzed by a F6PE; and converting the T6P to tagatose, catalyzed by a T6PP, using enzymes with higher activities compared to F6PEs and T6PPs previously used in a process to produce tagatose.

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.

This disclosure provides epimerase enzymes useful for commercial scale production of allulose from fructose. The disclosed enzymes (“epimerase variants”) are variants of Burkholderia multivorans CGD1 xylose isomerase engineered to have improved catalytic activity of about 1.5- to 2-fold compared with the parent enzyme.

Provided are a hexuronate C4-epimerase variant with improved activity in converting D-fructose by D-tagatose of hexuronate C4-epimerase and a method for production of D-tagatose using them.

The present invention relates to the technical field of microbial fermentation engineering, and specifically to a method for producing psicose 3-epimerase by high-density fermentation. In view of the low expression level of psicose 3-epimerase and other problems existing in the current fermentation, by controlling the feeding rate in the fermentation process, improving the culture temperature in the middle and late stages of fermentation and other measures in the present invention, the OD value during the fermentation with recombinant Bacillus subtilis and the total enzyme activity of psicose 3-epimerase in the fermentation broth are significantly increased, the expression of psicose 3-epimerase is markedly improved, and the production cost of allulose is reduced. Therefore, the present invention has a very broad prospect of application in industry.

The present application relates to a psicose-6-phosphate phosphatase comprising motif A and motif B, a composition for producing D-psicose comprising the enzyme, and a method for producing D-psicose using the enzyme.

Provided are a novel D-psicose 3-epimerase and a method for preparing psicose using the same.

A gene expression cassette capable of producing psicose at high yield with high stability, a GRAS (Generally recognized as safe) microorganism, a method of producing the enzyme by using the GRAS microorganism, and a method of producing the psicose by using the GRAS microorganism and enzyme are provided.

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).

Provided herein are methods for identifying and isolating polynucleotides coding for polypeptides having D-allulose 3-epimerase activity from a wide variety of microorganisms. Also provided are nucleic acid constructs, vectors and recombinant host cells comprising the polynucleotides coding for D-allulose 3-epimerase activity as well as methods for producing allulose from fructose using said recombinant host cells having D-allulose 3-epimerase activity or the D-allulose 3-epimerase enzyme of said recombinant host cells having D-allulose 3-epimerase activity.