Microorganism for producing pantoic acid, and construction method therefor and application thereof

A method of constructing a recombinant Escherichia coli, comprising modifying a starting Escherichia coli per the following steps of A1-A25 to obtain the recombinant Escherichia coli:

• A1. introducing and expressing an alsS gene encoding acetolactate synthase;
• A2. replacing the promoter of ilvB gene encoding the large subunit of acetolactate synthase I with M1-93 promoter, wherein the M1-93 promoter is a DNA molecule, wherein the nucleotide sequence of one strand of the DNA molecule is set forth as SEQ ID NO:
• 3;
• A3. replacing the promoter of ilvG gene encoding the large subunit of acetolactate synthase II with the M1-93 promoter;
• A4. mutating the ilvH gene encoding a regulatory subunit of acetolactate synthase III to an ilvH mutant gene, wherein the ilvH mutant gene encodes the protein of SEQ ID NO:
• 5;
• A5. introducing and expressing an ilvC gene encoding acetohydroxyl-acid reductoisomerase;
• A6. introducing and expressing an ilvD gene encoding dihydroxy-acid dehydratase;
• A7. introducing and expressing a panB gene encoding 3-methyl-2-oxobutanoate hydroxymethyltransferase derived from Escherichia coli, which is designated as E-panB gene;
• A8. introducing and expressing a panE gene encoding 2-dehydropantothenate-2-reductase;
• A9. introducing and expressing a glyA gene encoding glycine hydroxymethyltransferase;
• A10. replacing the promoter of gcvT gene encoding aminomethyltransferase with the M1-93 promoter;
• A11. replacing the promoter of gcvP gene encoding glycine decarboxylase with the M1-93 promoter;
• A12. introducing and expressing a panB gene encoding 3-methyl-2-oxobutanoate hydroxymethyltransferase derived from Corynebacterium glutamicum, which is designated as C-panB gene;
• A13. mutating the ilvE gene encoding branched-chain amino acid aminotransferase to an ilvE mutant gene, wherein the ilvE mutant gene encodes the protein of SEQ ID NO:
• 12;
• A14. introducing and expressing a serA gene encoding phosphoglycerate dehydrogenase;
• A15. introducing and expressing a serC gene encoding phosphoserine/phosphohydroxythreonine aminotransferase and a serB gene encoding phosphoserine phosphatase;
• A16. knocking out the sdaA gene encoding L-serine deaminase I;
• A17. knocking out the tdcD gene encoding propionate kinase and the tdcE gene encoding formate acetyltransferase;
• A18. knocking out the adhE gene encoding alcohol dehydrogenase;
• A19. knocking out the pflB gene encoding pyruvate formate lyase;
• A20. knocking out the frd gene encoding fumarate reductase;
• A21. knocking out the ldhA gene encoding lactate dehydrogenase;
• A22. knocking out the mgsA gene encoding methylglyoxal synthase;
• A23. knocking out the pta gene encoding the phosphate acetyltransferase and the ackA gene encoding acetate kinase;
• A24. knocking out the ara gene encoding ribokinase and
• A25. knocking out the avtA gene encoding valine-pyruvate transaminase.