Mutant bacterial strains of the genus
The invention relates to mutant strains of the genus Sphingomonas which have a mutation in at least one gene encoding a protein involved in polyhydroxybutyrate (“PHB”) synthesis that allows the mutant strains to produce PHB-deficient Sphingans. The invention is also directed to a process for preparing a clarified Sphingan solution comprising heating aqueous Sphingan solution, in particular PUB-deficient Sphingan solution, to a clarification temperature of about 30° C. to about 70° C., and treating the solution with a clarification agent and enzymes. In addition, the invention is directed to a food or industrial product comprising a PHB-deficient and/or clarified Sphingan. One particular embodiment of the invention is directed to a clarified, PHB-deficient high-acyl gellan and the processes of making thereof.
1. An isolated DNA from a mutant strain of a genus Sphingomonas , wherein said DNA comprises a mutated phaC gene encoding a polyhydroxybutyrate (PHB) synthase, and wherein said mutant strain produces sphingan without producing PHB.
2. The isolated DNA of claim 1 , wherein said DNA comprises a nucleotide sequence set forth in SEQ ID NO:7.
3. The isolated DNA of claim 2 , wherein said DNA further comprises flanking regions.
4. The isolated DNA of claim 3 , wherein said DNA comprises a nucleotide sequence set forth in SEQ ID NO:13.
5. The isolated DNA of claim 1 , wherein said PHB synthase comprises an amino acid sequence set forth in SEQ ID NO:8.
6. A vector comprising the isolated DNA of claim 1 .
7. A vector comprising the isolated DNA of claim 2 .
8. A vector comprising the isolated DNA of claim 3 .
9. A vector comprising the isolated DNA of claim 4 .
10. The isolated DNA of claim 1 , wherein said sphingan is gellan, diutan (S-657), welan (S-130), rhamsan (S-194), S-198, S-7, S-88, NW-11, or B-16.
11. The isolated DNA of claim 1 , wherein said sphingan is gellan.
12. The isolated DNA of claim 1 , wherein said sphingan is diutan.
13. A recombinant DNA comprising a mutated phaC gene encoding a polyhydroxybutyrate (PHB) synthase, wherein a Sphingomonas strain comprising said recombinant DNA produces sphingan without producing PHB.
14. The recombinant DNA of claim 13 , wherein said DNA comprises a nucleotide sequence set forth in SEQ ID NO:7.
15. The recombinant DNA of claim 14 , wherein said DNA further comprises flanking regions.
16. The recombinant DNA of claim 15 , wherein said DNA comprises a nucleotide sequence set forth in SEQ ID NO:13.
17. The recombinant DNA of claim 13 , wherein said PHB synthase comprises an amino acid sequence set forth in SEQ ID NO:8.
18. A recombinant vector comprising the recombinant DNA of claim 13 .
19. A recombinant vector comprising the recombinant DNA of claim 14 .
20. A recombinant vector comprising the recombinant DNA of claim 15 .
21. A recombinant vector comprising the recombinant DNA of claim 16 .
22. The recombinant DNA of claim 13 , wherein said sphingan is gellan, diutan (S-657), welan (S-130), rhamsan (S-194), S-198, S-7, S-88, NW-11, or B-16.