Enzymatic production of D-allulose

1. An enzymatic process for preparing D-allulose, the process comprising the steps of: (i) converting fructose 6-phosphate (F6P) to allulose 6-phosphate (A6P), catalyzed by an allulose 6-phosphate 3-epimerase comprising the amino acid sequence which has at least 85% sequence identity to SEQ ID NO:3 or 6; and (ii) converting the A6P produced to allulose, catalyzed by an allulose 6-phosphate phosphatase comprising the amino acid sequence which has at least 85% sequence identity to SEQ ID NO:9.

2. The process of claim 1 , further comprising a step of converting glucose 6-phosphate (G6P) to the F6P, wherein the step is catalyzed by phosphoglucoisomerase (PGI).

3. The process of claim 2 , further comprising the step of converting glucose 1-phosphate (G1P) to the G6P, wherein the step is catalyzed by phosphoglucomutase (PGM).

4. The process of claim 3 , further comprising the step of converting a saccharide to the G1P, wherein the step is catalyzed by at least one enzyme, wherein the saccharide is selected from the group consisting of a starch or derivative thereof, cellulose or a derivative thereof and sucrose.

5. The process of claim 4 , wherein at least one enzyme is selected from the group consisting of alpha-glucan phosphorylase (αGP), maltose phosphorylase, sucrose phosphorylase, cellodextrin phosphorylase, cellobiose phosphorylase, and cellulose phosphorylase.

6. The process of claim 4 , wherein the saccharide is starch or a derivative thereof selected from the group consisting of amylose, amylopectin, soluble starch, amylodextrin, maltodextrin, maltose, and glucose.

7. The process of claim 6 , further comprising the step of converting the starch to a starch derivative wherein the starch derivative is prepared by enzymatic hydrolysis of starch or by acid hydrolysis of starch.

8. The process of claim 7 , wherein the starch derivative is prepared by enzymatic hydrolysis of starch catalyzed by isoamylase, pullulanase, alpha-amylase, or a combination thereof.

9. The process of claim 6 , wherein 4-glucan transferase (4GT) is added to the process.

10. The process of claim 2 , further comprising:

the step of converting glucose to the G6P, wherein the step is catalyzed by at least one enzyme, and optionally, the step of converting sucrose to the glucose, wherein the step is catalyzed by at least one enzyme.

11. The process of claim 1 , further comprising:

the step of converting fructose to the F6P, wherein the step is catalyzed by at least one enzyme; and optionally, the step of converting sucrose to the fructose, wherein the step is catalyzed by at least one enzyme.

12. The process of claim 1 , wherein the process steps are conducted at a temperature ranging from 37° C. to 95° C., and/or at a pH ranging from 5.0 to 8.0.

13. The process of claim 1 , wherein the process steps are conducted in one bioreactor.

14. The process of claim 1 , wherein the process steps are conducted in the presence of Co 2+ .

15. An enzymatic process for preparing D-allulose from a saccharide, the process comprising the process steps of: (i) converting fructose 6-phosphate (F6P) to allulose 6-phosphate (A6P), catalyzed by an allulose 6-phosphate 3-epimerase (A6PE) comprising the amino acid sequence which has at least 85% sequence identity to SEQ ID NO:3 or 6; and (ii) converting the A6P produced to allulose, catalyzed by an allulose 6-phosphate phosphatase (A6PP) comprising the amino acid sequence which has at least 85% sequence identity to SEQ ID NO:9; wherein the process steps are conducted at phosphate concentration from 0.1 mM to 150 mM.

16. The process of claim 15 , further comprising a step of converting glucose 6-phosphate (G6P) to the F6P, wherein the step is catalyzed by phosphoglucoisomerase (PGI).

17. The process of claim 16 , further comprising the step of converting glucose 1-phosphate (G1P) to the G6P, wherein the step is catalyzed by phosphoglucomutase (PGM).

18. The process of claim 17 , further comprising the step of converting a saccharide to the G1P, wherein the step is catalyzed by at least one enzyme, wherein the saccharide is selected from the group consisting of a starch or derivative thereof, cellulose or a derivative thereof and sucrose.

19. The process of claim 18 , wherein at least one enzyme is selected from the group consisting of alpha-glucan phosphorylase (αGP), maltose phosphorylase, sucrose phosphorylase, cellodextrin phosphorylase, cellobiose phosphorylase, and cellulose phosphorylase.

20. The process of claim 18 , wherein the saccharide is starch or a derivative thereof selected from the group consisting of amylose, amylopectin, soluble starch, amylodextrin, maltodextrin, maltose, and glucose.

21. The process of claim 20 , further comprising the step of converting starch to a starch derivative wherein the starch derivative is prepared by enzymatic hydrolysis of starch or by acid hydrolysis of starch, wherein the starch derivative is prepared by enzymatic hydrolysis of starch catalyzed by isoamylase, pullulanase, alpha-amylase, or a combination thereof.

22. The process of claim 20 , wherein 4-glucan transferase (4GT) is added to the process.

23. The process of claim 16 , further comprising:

the step of converting glucose to the G6P, wherein the step is catalyzed by at least one enzyme, and optionally, the step of converting sucrose to the glucose, wherein the step is catalyzed by at least one enzyme.

24. The process of claim 15 , further comprising:

the step of converting fructose to the F6P, wherein the step is catalyzed by at least one enzyme; and optionally, the step of converting sucrose to the fructose, wherein the step is catalyzed by at least one enzyme.

25. The process of claim 15 , wherein the process steps are conducted at a temperature ranging from 37° C. to 95° C., and/or at a pH ranging from 5.0 to.

26. The process of claim 15 , wherein the process steps are conducted in one bioreactor.

27. The process of claim 15 , wherein the phosphate concentration is from 0.1 mM to 55 mM.