Method of producing l-lysine

Abstract

The L-lysine-producing ability and the L-lysine-producing speed are improved in a coryneform bacterium harboring an aspartokinase in which feedback inhibition by L-lysine and L-threonine is substantially desensitized, by successively enhancing DNA coding for a dihydrodipicolinate reductase, DNA coding for a dihydrodipicolinate synthase, DNA coding for a diaminopimelate decarboxylase, and DNA coding for a diaminopimelate dehydrogenase.

What is claimed is:  
     
         1 . A recombinant DNA autonomously replicable in cells of coryneform bacteria, comprising a DNA sequence coding for an aspartokinase in which feedback inhibition by L-lysine and L-threonine is substantially desensitized, and a DNA sequence coding for a dihydrodipicolinate reductase.  
     
     
         2 . The recombinant DNA according to  claim 1 , further comprising a DNA sequence coding for a dihydrodipicolinate synthase.  
     
     
         3 . The recombinant DNA according to  claim 2 , further comprising a DNA sequence coding for a diaminopimelate decarboxylase.  
     
     
         4 . The recombinant DNA according to  claim 3 , further comprising a DNA sequence coding for a diaminopimelate dehydrogenase.  
     
     
         5 . The recombinant DNA according to any one of  claims 1  to  4 , wherein said aspartokinase in which feedback inhibition by L-lysine and L-threonine is substantially desensitized is an aspartokinase originating from coryneform bacteria, and wherein said aspartokinase is provided as a mutant aspartokinase in which a 279th alanine residue as counted from its N-terminal is changed into an amino acid residue other than alanine and other than acidic amino acid in its α-subunit, and a 30th alanine residue is changed into an amino acid residue other than alanine and other than acidic amino acid in its β-subunit.  
     
     
         6 . The recombinant DNA according to any one of  claims 1  to  4 , wherein said DNA sequence coding for the dihydrodipicolinate reductase codes for an amino acid sequence depicted in SEQ ID NO: 15 in Sequence Listing, or an amino acid sequence substantially the same as the amino acid sequence depicted in SEQ ID NO: 15.  
     
     
         7 . The recombinant DNA according to  claim 2 , wherein said DNA sequence coding for the dihydrodipicolinate synthase codes for an amino acid sequence depicted in SEQ ID NO: 11 in Sequence Listing, or an amino acid sequence substantially the same as the amino acid sequence depicted in SEQ ID NO: 11.  
     
     
         8 . The recombinant DNA according to  claim 3 , wherein said DNA sequence coding for the diaminopimelate decarboxylase codes for an amino acid sequence depicted in SEQ ID NO: 19 in Sequence Listing, or an amino acid sequence substantially the same as the amino acid sequence depicted in SEQ ID NO: 19.  
     
     
         9 . The recombinant DNA according to  claim 4 , wherein said DNA sequence coding for the diaminopimelate dehydrogenase codes for an amino acid sequence depicted in SEQ ID NO: 24 in Sequence Listing, or an amino acid sequence substantially the same as the amino acid sequence depicted in SEQ ID NO: 24.  
     
     
         10 . A coryneform bacterium harboring an aspartokinase in which feedback inhibition by L-lysine and L-threonine is substantially desensitized, and comprising an enhanced DNA sequence coding for a dihydrodipicolinate reductase.  
     
     
         11 . The coryneform bacterium according to  claim 10 , transformed by introduction of the recombinant DNA as defined in  claim 1 .  
     
     
         12 . The coryneform bacterium according to  claim 10 , further comprising an enhanced DNA sequence coding for a dihydrodipicolinate synthase.  
     
     
         13 . The coryneform bacterium according to  claim 12 , transformed by introduction of the recombinant DNA as defined in  claim 2 .  
     
     
         14 . The coryneform bacterium according to  claim 12 , further comprising an enhanced DNA sequence coding for a diaminopimelate decarboxylase.  
     
     
         15 . The coryneform bacterium according to  claim 14 , transformed by introduction of the recombinant DNA as defined in  claim 3 .  
     
     
         16 . The coryneform bacterium according to  claim 14 , further comprising an enhanced DNA sequence coding for a diaminopimelate dehydrogenase.  
     
     
         17 . The coryneform bacterium according to  claim 16 , transformed by introduction of the recombinant DNA as defined in  claim 4 .  
     
     
         18 . A method for producing L-lysine comprising the steps of cultivating said coryneform bacterium as defined in any one of  claims 10  to  17  in an appropriate medium, producing and accumulating L-lysine in a culture of the bacterium, and collecting L-lysine from the culture.