| 摘要 |
PROBLEM TO BE SOLVED: To obtain a new kind of microorganisms having the ability to produce an L-amino acid, inviable in a synthetic medium containing the L-amino acid as the sole nitrogen source at a specific concentration of lower, and to be used in producing an L-amino acid useful as/for medicines, foods and feed additives. SOLUTION: This new kind of microorganisms, which belongs to the genus Corynebacterium, Brevibacterium, Escherichia, Serratia, or Arthrobacter [e.g. Escherichia coli H-9244 THN-1 strain (FERM BP-5985)], has the ability to produce an L-amino acid, being inviable in a synthetic medium containing the L-amino acid as the sole nitrogen source at <=5 mg/mL, and useful in e.g. the industrial production of an L-amino acid such as L-threonine used in medicines, foods and feed additives. This new kind of microorganisms was obtained by subjecting diaminopimelic acid-non-demanding Escherichia coli H-7700 to mutation treatment using N-methyl-N'-nitro-N-nitrosoguanidine followed by screening a strain having the high ability to produce L-threonine. |
