Method for microbial production of xylitol from arabinose
View Patent ↗Recombinant microorganisms are useful for producing xylitol by fermentation of arabinose. The recombinant microorganisms are produced by transformation of host microorganisms with heterologous polynucleotide sequences coding for each of L-xylulose reductase, D-tagatose 3-epimerase, and L-arabinose isomerase, which transformants express the heterologous polynucleotides at a sufficient functional level to be effective to produce xylitol from arabinose. Production of xylitol is effected by contacting these recombinant microorganisms with a substrate comprising arabinose under conditions effective to produce xylitol from arabinose.
1. A recombinant L-arabinose-fermenting microorganism comprising heterologous polynucleotide sequences coding for L-xylulose reductase, D-tagatose 3-epimerase, and L-arabinose isomerase, wherein said microorganism expresses said heterologous polynucleotides at a sufficient functional level to be effective to produce xylitol from arabinose, and further wherein said microorganism is selected from the group consisting of a gram negative bacterium and a yeast.
2. The recombinant microorganism of claim 1 produced by transformation of a parent microorganism with said heterologous polynucleotide sequences coding for Lxylulose reductase, D-tagatose 3-epimerase, and L-arabinose isomerase, and further wherein said parent microorganism lacks one or more enzymes in the pathway for converting L-ribulose or L-xylulose or both to D-xylulose 5-phosphate and wherein said microorganism is E. coli.
3. The recombinant microorganism of claim 2 wherein said parent microorganism lacks ribulokinase (AraB) activity for the phosphorylation of L-ribulose to L-ribulose 5-phosphate.
4. The recombinant microorganism of claim 2 wherein said parent microorganism lacks L-xylulokinase (lyxK) activity for the phosphorylation of L-xylulose to L-xylulose 5-phosphate.
5. The recombinant microorganism of claim 2 wherein said parent microorganism lacks both ribulokinase (AraB) activity for the phosphorylation of L-ribulose to L-ribulose 5-phosphate, and L-xylulokinase (lyxK) activity for the phosphorylation of L-xylulose to L-xylulose 5-phosphate.
6. The recombinant microorganism of claim 2 wherein said parent microorganism lacks a ptsG gene or has an inactive ptsG gene.
7. The recombinant microorganism of claim 1 wherein said bacterium comprises a gram negative bacterium.
8. A nucleic acid construct comprising polynucleotide sequences coding for each of L-xylulose reductase, D-tagatose 3-epimerase, and L-arabinose isomerase, wherein said polynucleotide sequences are operably linked to one or more expression control sequences.
9. The nucleic acid construct of claim 8 comprising a plasmid.
10. A recombinant microorganism stably transformed with the nucleic acid construct of claim 8 , and further wherein said microorganism is selected from the group consisting of a gram negative bacterium and a yeast.
11. The recombinant microorganism of claim 10 wherein said recombinant microorganism lacks one or more enzymes in the pathway for Converting L-ribulose or L-xylulose or both to D-xylulose 5-phosphate and wherein said microorganism is E. coli.
12. The recombinant microorganism of claim 11 wherein said recombinant microorganism lacks ribulokinase activity for the phosphorylation of L-ribulose to L-ribulose 5-phosphate.
13. The recombinant microorganism of claim 11 wherein said recombinant microorganism lacks L-xylulokinase (lyxK) activity for the phosphorylation of L-xylulose to L-xylulose 5-phosphate.
14. The recombinant microorganism of claim 11 wherein said recombinant microorganism lacks both ribulokinase (AraB) activity for the phosphorylation of L-ribulose to L-ribulose 5-phosphate, and L-xylulokinase (lyxK) activity for the phosphorylation of L-xylulose to L-xylulose 5-phosphate.
15. The recombinant microorganism of claim 11 wherein said recombinant microorganism lacks a ptsG gene or has an inactive ptsG gene.
16. The recombinant microorganism of claim 10 wherein Said bacterium comprises a gram negative bacterium.
17. The recombinant microorganism of claim 1 wherein said microorganism is Escherichia coli.
18. The recombinant microorganism of claim 1 wherein said microorganism is a yeast.
19. The recombinant microorganism of claim 10 wherein said microorganism is Escherichia coli.
20. The recombinant microorganism of claim 10 wherein said microorganism is a yeast.
21. A recombinant L-arabinose-fermenting Escherichia coli comprising heterologous polynucleotide sequences coding for L-xylulose reductase, D-tagatose 3-epimerase, and L-arabinose isomerase, wherein said Escherichia coli expresses said heterologous polynucleotides at a sufficient functional level to be effective to produce xylitol from arabinose, and further wherein said Escherichia coli lacks ribulokinase (AraB) activity for the phosphorylation of L-ribulose to L-ribulose 5-phosphate.