METHOD FOR PRODUCING AN ORGANIC ACID

• US 20100068774A1
• Filed: 10/09/2009
• Published: 03/18/2010
• Est. Priority Date: 04/10/2007
• Status: Active Grant

• Current Assignee: Ajinomoto Co., Inc.
• Original Assignee: Ajinomoto Co., Inc.
• Inventors: Mihara, Yoko, Fukui, Keita
• Granted Patent: US 9,080,189 B2
• Time in Patent Office: Days
• US Class Current: 435/145
• CPC Class Codes: C12P 7/46 Dicarboxylic acids having four or less carbon atoms, e.g. fumaric acid, maleic acid
• CPC Class Codes: C12P 7/625 Polyesters of hydroxy carboxylic acids

Abstract

An organic acid is produced by allowing a bacterium which has an ability to produce an organic acid and has been modified so that expression of the sucE1 and mdh genes are enhanced, or a product obtained by processing the bacterium, to act on an organic raw material in a reaction mixture containing carbonate ions, bicarbonate ions, or carbon dioxide gas, and collecting the organic acid.

Claims

1. A method for producing an organic acid comprising:

A) allowing a substance to act on an organic raw material in a reaction mixture containing carbonate ions, bicarbonate ions, or carbon dioxide gas, wherein the substance is selected from the group consisting of;

i) a bacterium which has an ability to produce an organic acid and has been modified to have enhanced expression of the sucE1 and mdh genes,

ii) a product obtained by processing the bacterium of i), and

iii) combinations thereof, and

B) collecting the organic acid.

2. The method according claim 1, wherein expression of the sucE1 and mdh genes under aerobic conditions is enhanced by 1.5 times or more as compared to an unmodified strain.

3. The method according to claim 1, wherein the bacterium is selected from the group consisting of coryneform bacteria, Bacillus bacteria, and Rhizobium bacteria.

4. The method according to claim 1, wherein enhanced expression is obtained by a method selected from the group consisting of

i) increasing the copy number of the sucE1 gene and/or the mdh gene,

ii) modifying an expression control sequence of the sucE1 gene and/or the mdh gene,

iii) replacing a promoter of the sucE1 gene and/or the mdh gene with a stronger promoter, and

iv) combinations thereof.

5. The method according to claim 4, wherein the stronger promoter is a constitutive expression promoter.

6. The method according to claim 4, wherein the stronger promoter is a promoter of a gene that encodes a protein selected from the group consisting of elongation factor Tu, cochaperonin GroES-chaperonin GroEL, thioredoxin reductase, phosphoglycerate mutase, peroxiredoxin, glycerol-3-phosphate dehydrogenase, 2,3-butanediol dehydrogenase, fructose bisphosphate aldolase, and superoxide dismutase.

7. The method according to claim 1, wherein the sucE1 gene is selected from the group consisting of:

(a) a DNA comprising the nucleotide sequence of the numbers 571 to 2187 of SEQ ID NO;

3, and

(b) a DNA which hybridizes with a nucleotide sequence complementary to the nucleotide sequence of the numbers 571 to 2187 of SEQ ID NO;

3 under stringent conditions, and the DNA improves the ability of the bacterium to produce succinic acid when expression of the DNA is enhanced in the bacterium.

8. The method according to claim 1, wherein the mdh gene is selected from the group consisting of:

(a) a DNA comprising the nucleotide sequence of the numbers 301 to 1287 of SEQ ID NO;

13, and

(b) a DNA which hybridizes with a nucleotide sequence complementary to the nucleotide sequence of the numbers 301 to 1287 of SEQ ID NO;

13 under stringent conditions, and codes for a protein having malate dehydrogenase activity.

9. The method according to claim 1, wherein the bacterium has been further modified so that lactate dehydrogenase activity is decreased to 10% or less as compared to lactate dehydrogenase activity in an unmodified strain.

10. The method according to claim 1, wherein the bacterium has been further modified so that pyruvate carboxylase activity is enhanced.

11. The method according to claim 1, wherein the organic acid is succinic acid.

12. A method for producing a succinic acid-containing polymer comprising:

A) producing succinic acid by the method according to claim 1, and

B) polymerizing the succinic acid.

13. The method according to claim 11, wherein the bacterium has been further modified so that succinate dehydrogenase activity is enhanced.

14. The method according to claim 1, wherein the organic acid is malic acid or fumaric acid.

15. The method according to claim 14, wherein the bacterium has been further modified so that succinate dehydrogenase activity is decreased to 10% or less as compared to succinate dehydrogenase activity in an unmodified strain.