Process for producing d-mannitol

• US 20040063183A1
• Filed: 10/30/2003
• Published: 04/01/2004
• Est. Priority Date: 12/20/2000
• Status: Abandoned Application

• Current Assignee: Niklas Von Weymarn, Ulla Airaksinen
• Original Assignee: Niklas Von Weymarn, Ulla Airaksinen
• Inventors: Weymarn, Niklas Von, Airaksinen, Ulla
• Application Number:
  US10/250,595
• Publication Number:
  US 20040063183A1
• Time in Patent Office: Days
• US Class Current: 435/158
• CPC Class Codes: C12P 7/18 polyhydric

Abstract

High concentration of free cells of heterofermentative lactic acid bacteria (LAB) in a resting or slowly growing state are used to convert fructose into mannitol. Efficient volumetric mannitol productivities and mannitol yields from fructose are achieved in a process applying cell-recycle, continuous stirred tank reactor and/or circulation techniques with native LAB cells or with LAB cells with inactivated fructokinase gene(s). Mannitol is recovered in high yield and purity with the aid of evaporation and cooling crystallization.

Claims

1. A process for the production of mannitol by bioconversion, comprising the steps of

bringing a high initial concentration of free, mannitol-producing lactic acid bacterial cells into contact with a low-nutrient medium supplemented with a substrate convertible into mannitol, and a cosubstrate, in a bioreactor system,

performing the bioconversion under conditions suitable for converting said substrate into mannitol,

separating the bacterial cells from the medium by filtration to obtain a cell-free solution,

recovering from the cell-free solution the mannitol produced, and

reusing the separated bacterial cells in the bioreactor system.

2. The process according to claim 1, wherein the bacterial cells are native lactic acid bacterial cells.

3. The process according to claim 2, wherein the bacterial cells are of the strain Leuconostoc mesenteroides ATCC-9135.

4. The process according to claim 1, wherein the bacterial cells are fructokinase-inactivated lactic acid bacterial cells.

5. The process according to claim 4, wherein the cells are of the strain Leuconostoc pseudomesenteroides BPT143 (DSM 14613).

6. The process according to claim 1, wherein the substrate is fructose.

7. The process according to claim 1, wherein the cosubstrate is glucose.

8. The process according to claim 1, wherein the bioconversion is performed until at least 70%, preferably 90% or more of the said substrate has been consumed.

9. The process according to claim 1, wherein an average volumetric mannitol productivity of at least 10 g/L/h is achieved.

10. The process according to claim 1, wherein the bioconversion is performed as a batch process in a bioreactor system comprising a bioconversion reactor unit and a filtration unit.

11. The process according to claim 10, comprising the steps of separating the bacterial cells from the medium after the bioconversion step, and reusing said cells in successive bioconversions.

12. The process according to claim 1, wherein the bioconversion is performed as a circulation process in a bioreactor system comprising a bioconversion reactor unit, a filtration unit and a mixing reactor unit.

13. The process according to claim 12, wherein the bacterial cells are circulated between the bioconversion reactor unit and the filtration unit.

14. The process according to claim 12 or 13, comprising the steps of leading the cell-free solution obtained by the filtration into the mixing reactor, and transferring the solution from the mixing reactor back to the bioconversion reactor unit.

15. The process according to any one of the claims 12 to 14, comprising emptying the mixing reactor after the bioconversion step, and re-filling it with said low-nutrient medium supplemented with said substrate and co-substrate, to run successive bio-conversions reusing said bacterial cells.

16. The process according to claim 1, wherein the bioconversion is performed as a continuous process in a bioreactor system comprising a mixing tank, a feed tank, a bioconversion reactor unit, a filtration unit and a recovery tank.

17. The process according to claim 16, wherein the bacterial cells are circulated between the bioconversion reactor unit and the filtration unit.

18. The process according to claim 16 or 17, comprising the steps of feeding the bioconversion reactor unit continuously with said low-nutrient medium supplemented with said substrate and co-substrate, and removing the cell-free solution gained by filtration from the bioreactor to withhold a constant volume in the bioconversion reactor unit.

19. The process according to any one of the claims 10 to 18, wherein the filtration unit is a tangential flow filtration unit.

20. The process according to any one of the claims 10 to 18, wherein said bioconversion is run in series or in parallel.

21. A bacterial strain of the genus Lactobacillus or Leuconostoc, in which the fructokinase enzyme(s) is/are inactivated.

22. The bacterial strain according to claim 21, in which the fructokinase enzyme(s) is/are inactivated by random mutagenesis.

23. The bacterial strain according to claim 22, which is Leuconostoc pseudomesenteroides BPT143 (DSM 14613).

24. The bacterial strain according to claim 21, in which the fructokinase enzyme(s) is/are inactivated by directed mutagenesis.

25. Use of a bacterial strain of the genus Lactobacillus or Leuconostoc, in which the fructokinase enzyme(s) is/are inactivated, for producing mannitol.