Targeted gene deletions for polysaccharide slime formers
View Patent ↗The present invention provides improved diutan polysaccharides produced by mutant Sphingomonas strains containing at least one genetic modification that favors slime-forming diutan production that exhibits increased viscosity. Methods of making the mutant Sphingomonas strains and the culture broth containing such mutant Sphingomonas strains are also provided.
1. A composition comprising a diutan polysaccharide which is produced by a process comprising recovering a diutan from a mutant Sphingomonas strain which contains at least one genetic modification that favors the production of diutan in a slime form, wherein said diutan as naturally produced by said mutant Sphingomonas strain imparts to a fluid an increased viscosity relative to an equivalent amount of diutan as naturally produced by a wild-type Sphingomonas strain ATCC 53159 wherein said gene mutations or deletions are in one or both of dpsN and dpsM genes and the Sphingomonas strain has deletion mutations in either or both dpsN and dpsM genes.
2. The composition of claim 1 wherein the increased viscosity is at least 30% more than an equivalent amount of diutan produced by strain ATCC 53159.
3. The composition of claim 1 wherein the increased viscosity is at least 40% more than an equivalent amount of diutan produced by strain ATCC 53159.
4. The composition of claim 1 wherein the increased viscosity is at least 50% more than an equivalent amount of diutan produced by strain ATCC 53159.
5. The composition of claim 1 wherein the increased viscosity is at least 60% more than the relative to an equivalent amount of diutan produced by strain ATCC 53159.
6. The composition of claim 1 wherein the increased viscosity is at least 70% more than the relative to an equivalent amount of diutan produced by strain ATCC 53159.
7. The composition of claim 1 wherein the increased viscosity is at least 80% more than the relative to an equivalent amount of diutan produced by strain ATCC 53159.
8. The composition of claim 1 wherein the increased viscosity is at least 90% more than the relative to an equivalent amount of diutan produced by strain ATCC 53159.
9. The composition of claim 1 wherein said mutant Sphingomonas strain is a slime forming Sphingomonas strain.
10. The composition of claim 9 wherein said mutant Sphingomonas strain has one or more gene mutations or deletions which convert the strain from capsule former to a slime-forming mutant.
11. The composition of claim 10 wherein the diutan produced by said mutant Sphingomonas strain comprises longer fibers than diutan as naturally produced by the wild-type Sphingomonas strain ATCC 53159.
12. The composition of claim 1 wherein the diutan is produced by a variant of Sphingomonas strain ATCC 53159 wherein said variant has been genetically engineered to eliminate an expression of dpsN gene.
13. The composition of claim 1 wherein the diutan is produced by a variant of Sphingomonas strain ATCC 53159 wherein said variant has been genetically engineered to eliminate an expression of dpsM gene.
14. The composition of claim 1 wherein the diutan is produced by a variant of Sphingomonas strain ATCC 53159 wherein said variant has been genetically engineered to eliminate an expression of both dpsM and dpsN genes.