Novel glucans and novel glucansucrases derived from lactic acid bacteria

• US 20050059633A1
• Filed: 07/22/2002
• Published: 03/17/2005
• Est. Priority Date: 07/20/2001
• Status: Abandoned Application

• Current Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno
• Inventors: Van Geel-Schuten, Gerritdina Hendrika
• Application Number:
  US10/484,218
• Publication Number:
  US 20050059633A1
• Time in Patent Office: Days
• US Class Current: 514/54
• CPC Class Codes: C12N 9/1051 Hexosyltransferases (2.4.1)
• CPC Class Codes: C12P 19/04 Polysaccharides, i.e. compounds containing more than five saccharide radicals attached to each other by glycosidic bonds
• CPC Class Codes: C12P 19/08 Dextran
• CPC Class Codes: C12P 19/18 produced by the action of a glycosyl transferase, e.g. alpha-, beta- or gamma-cyclodextrins

Abstract

The invention pertains to glucans capable of being produced by glucosyltransferase activity of a lactic acid bacterium on a sucrose substrate, the glucan having an average molecular weight between 10 kDa and 1 GDa, consisting essentially of alpha (1,3)- and alpha (1,6)-linked anhydroglucose units (AGU) and to glucansucrases capable of producing these glucans from sucrose. The glucans have thickening and anti-corrosive properties. The glucans can be chemically modified.

Claims

1-20. -20. (cancelled)

21. A process of producing a glucan having at least 10 anhydroglucose units, having a backbone consisting essentially of α

(1,3)- and/or α

(1,6)-linked anhydroglucose units (AGU), comprising subjecting sucrose to the activity of a glucosyltransferase produced by a Lactobacillus strain capable of producing α

(1,3)- and/or α

(1,6)-linked glucans, or to the Lactobacillus strain capable of expressing the glucosylfransferase.

22. A Lactobacillus strain capable of producing, in the presence of sucrose, a glucan having at least 10 anhydroglucose units (AGU) having a backbone consisting essentially of α

(1,3)- and/or α

(1,6)-linked AGU.

23. A glucan capable of being produced by glucosyltransferase activity of a lactic acid bacterium on a sucrose substrate, the glucan having an average molecular weight between 10 kDa and 1 GDa, and having a backbone consisting essentially of α

(1,3)- and α

(1,6)-linked anhydroglucose units (AGU).

24. The glucan according to claim 23, which has an average molecular weight between 10 kDa and 50 Mda.

25. The glucan according to claim 23, which is capable of being produced by glucosyltransferase activity of a Lactobacillus species.

26. The glucan according to claim 25, comprising 15-80% of α

(1,3)-linked AGU, 2-80% of α

(1,6)-linked AGU, and 2-25% of α

-(1,3,6)-linked AGU.

27. The glucan according to claim 26, having an average molecular weight of 50 kDa-1 MDa and comprising 30-45% of α

(1,3)-linked AGU, 30-45% of α

(1,6)-linked AGU, and 3-13% of α

(1,3,6)-linked AGU.

28. The glucan according to claim 26, having an average molecular weight of 10-50 MDa and comprising 15-26% α

(1,3)-linked AGU, 30-50% of α

(1,6)-linked AGU, 5-20% of α

(1,3,6)-linked AGU.

29. The glucan according to claim 26, having an average molecular weight of 1-50 MDa and comprising 45-60% of α

(1,3)-linked AGU, 4-10% of α

(1,6)-linked AGU, and 10-20% of α

(1,3,6)-linked AGU.

31. A protein having glucosyltransferase activity, capable of producing, in the presence of sucrose, a glucan according to claim 23.

32. The protein according to claim 31, comprising an amino acid sequence of at least 100 amino acids, the sequence exhibiting at least 80% amino acid identity with any one of the amino acid sequences of SEQ ID No. 2, 4, 8, 10, 12, 14, 16, 18, 20 and 22, and/or having a stretch of 100 amino acids having at least 90%, amino acid identity with any one of the said amino acid sequences.

33. The protein according to claim 31, comprising an amino acid sequence having at least 99% amino acid identity with the amino acid sequence of SEQ ID No. 6, and/or having a stretch of 100 amino acids having 100% amino acid identity with the amino acid sequence of SEQ ID No. 6.

34. A nucleic acid sequence encoding the protein according to claim 31.

35. A recombinant host cell containing one or more copies of a nucleic acid construct comprising a nucleic acid sequence according to claim 34 and capable of expressing a protein having glucosyl-transferase activity.

36. A Lactobacillus strain, capable of producing the glucan according to claim 23.

37. The Lactobacillus strain according to claim 36, corresponding to strain 33, 180 or ML1 as described herein.

40. A chemically modified glucan, which is obtained by 2,3-oxidation, 6-oxidation, phosphorylation, acylation, alkylation, hydroxyalkylation, carboxymethylation, aminoalkylation of one or more AGU of a glucan according to claim 23.

41. A method of thickening a water-based composition, coprising incorporating in said composition the glucan according to claim 23.

42. A method of controlling corrosion of a substrate, comprising applying onto the substrate the glucan according to claim 23.

43. A method of improving the condition of the gastrointestinal tract, modulating immune properties, controlling ulcers or lowering cholesterol levels, comprising administering an effective amount of the glucan according to claim 23.

44. A method of improving the condition of the gastrointestinal tract, comprising administering an effective amount of a Lactobacillus bacterium capable of producing the glucan according to claim 23 as a probiotic agent, or together with an indigestible glucan, as a synbiotic agent.

45. A nutritional or pharmaceutical composition comprising the glucan of claim 23 as a prebiotic or as a bioactive agent.

30. A glucan capable of being produced by glucosyltransferase activity of a lactic acid bacterium on a sucrose substrate, having an average molecular weight of 10-50 MDa and comprising 80-99% of α

(1,6)-linked AGU and 0-15% of α

(1,3)-linked AGU.

38. A Leuconostoc strain, capable of producing the glucan according to claim 30.

39. The Leuconostoc strain according to claim 38 corresponding to strain 86, deposited under accession number LMG P-20350.