Enterobacteriaceae strains with an attenuated aspA gene for the fermentative production of amino acids

1. A process for the preparation of an L-amino acid selected from the group consisting of L-lysine, L-valine, L-homoserine and L-threonine, comprising: culturing a recombinant microorganism of the genus Escherichia for a time and under conditions suitable for the production of said L-amino acid, wherein: said recombinant microorganism has a deletion or mutation of the gene encoding aspartate animonium lyase (aspA) and having the amino acid sequence of SEQ ID NO:2; and wherein said deletion or mutation results in the elimination of aspA enzymatic activity in said microorganism.

2. The process of claim 1 , wherein said L-amino acid is L-lysine.

3. The process of claim 1 , wherein said L-amino acid is L-valine.

4. The process of claim 1 , wherein said L-amino acid is L-homosenne.

5. The process of claim 1 , wherein said L-amino acid is L-threonine.

6. The process of any one of claims 2 - 5 , wherein said gene is deleted or mutated by one or more methods selected from the group consisting of:

a) deletion mutagenesis with deletion of at least one base pair in said gene encoding aspartate ammonium lyase (aspA);

b) insertional mutagenesis due to homologous recombination; and

c) transition or transversion mutagenesis with incorporation of a nonsense mutation into said gene encoding aspartate ammonium lyase (aspA).

7. The process of any one of claims 2 – 5 , further comprising:

a) allowing said L-amino acid to become concentrated in said medium or in the cells of said recombinant microorganism; and

b) after step a), isolating said L-amino acid along with 0–100% of the biomass or other constituents in said medium.

8. The process of claim 6 , further comprising:

a) allowing said L-amino acid to become concentrated in said medium or in the cells of said recombinant microorganism; and

b) after step a), isolating said L-amino acid along with 0–100% of the biomass or other constituents in said medium.

9. The process of claim 1 , wherein:

a) said L-amino acid is L-lysine or L-threonine;

b) said gene is deleted or mutated by insertional mutagenesis due to homologous recombination; and

c) said process further comprises:

i) allowing said L-amino acid to become concentrated in said medium or in the cells of said recombinant microorganism; and

ii) after step i), isolating said L-amino acid along with 0–100% of the biomass or other constituents in said medium.

10. The process of claim 7 , wherein said recombinant microorganism overexpresses one or more gene(s) selected from the group consisting of:

a) the E. coli thrABC operon which codes for aspartate kinase, homoserine dehydrogenase, homoserine kinase and threonine synthase;

b) the C. glutamicum pyc gene which codes for pyruvate carboxylase;

c) the E. coli pps gene which codes for phosphoenol pyruvate synthase;

d) the E. coli ppc gene which codes for phosphoenol pyruvate carboxylase;

e) the E. coli pntA and pntB genes which code for transhydrogenase;

f) the E. cloi rhtB gene which imparts homoserine resistance;

g) the E. coli mqo gene which codes for malate:quinone oxidoreductase;

h) the E. coli rhtC gene which imparts threonine resistance;

i) the C. glutamicum thrE gene which codes for the threonine export protein;

j) the E. coli gdhA gene which codes for glutamate dehydrogenase;

k) the E. coli hns gene which codes for the DNA-binding protein HLP-II;

l) the E. coli pgm gene which codes for phosphoglucomutase;

m) the E. coli fba gene which codes for fructose biphosphate aldolase;

n) the E. coli ptsH gene which codes for the phosphohistidine protein hexose phosphotransferase;

o) the E. coli ptsl gene which codes for enzyme I of the phosphotransferase system;

p) the E. coli crr gene which codes for the glucose-specific IIA component;

q) the E. coli ptsG gene which codes for the glucose-specific IIBC component;

r) the E. coli lrp gene which codes for the regulator of the leucine regulon;

s) the E. coli mopB gene which codes for 10 Kd chaperone;

t) the E. coli ahpC gene which codes for the small sub-unit of alkyl hydroperoxide reductase;

u) the E. coli ahpF gene which codes for the large sub-unit of alkyl hydroperoxide reductase;

v) the E. coli cysK gene which codes for cysteine synthase A;

w) the E. coli cysB gene which codes for the regulator of the cys regulon;

x) the E. coli cysJ gene which codes for the flavoprotein of NADPH sulfite reductase;

y) the E. coli cysI gene which codes for the haemoprotein of NADPH sulfite reductase; and

z) the E. coli cysH gene which codes for adenylyl sulfate reductase.

11. The process of claim 7 , wherein one or more E. coli gene(s) are deleted in said microorganism, said one or more genes being selected from the group consisting of:

a) the tdh gene which codes for threonine dehydrogenase;

b) the mdh gene which codes for malate dehydrogenase;

c) the gene product of the open reading frame (orf) yjfA;

d) the gene product of the open reading frame (orf) ytfP;

e) the pckA gene which codes for phosphoenol pyruvate carboxykinase;

f) the poxB gene which codes for pyruvate oxidase;

g) the aceA gene which codes for isocitrate lyase;

h) the dgsA gene which codes for the DgsA regulator of the phosphotransferase system;

i) the fruR gene which codes for the fructose repressor;

j) the rpoS gene which codes for the sigma 38 factor;

k) the aceB gene which codes for malate synthase A;

l) the aceK gene which codes for isocitrate dehydrogenase kinase/phosphatase; and

m) the ugpB gene which codes for the periplasmic binding protein of the sn-glycerol 3-phosphate transport system.