Patent ID: 7368266

Claim:
A method of producing L-threonine, comprising: constructing a recombinant chromosomal DNA integration system comprising one or more copies of each of a nucleic acid encoding phosphoenolpyruvate carboxylase which is obtained using PCR primers of SEQ ID NO: 1 and SEQ ID NO: 2 from Escherichia coli strain TF 4076 Accession No. KFCC 10718 and a threonine operon from a microorganism belonging to the Eseherichia or Corynebacterium genus resistant to threonine analogs, lysine analogs, isoleucine analogs, or methionine analogs; introducing the recombinant chromosomal DNA integration system into a microorganism belonging to the Escherichia genus to integrate the one or more additional copies into the lacZ gene site of the Eseherichia chromosomal DNA while the microorganism's inherent phosphoenolpyruvate carboxylase gene and threonine operon remain; culturing the transformed Escherichia with substrates to produce L-threonine; and isolating the produced L-threonine.