BREEDING OF AMINO ACID-PRODUCING STRAIN, BRED MICROBIAL STRAIN AND PRODUCTION OF AMINO ACID USING THE STRAIN

摘要

PURPOSE:To provide a method for breeding an amino acid-producing strain, the microbial strain bred by the method and a process for the production of amino acid using the strain. CONSTITUTION:The mutant strain to be used as the starting material of the present process is a strain subjected to mutation to influence on an aminoacyl t-RNA synthetase corresponding to the amino acid to be produced and imparted with an auxotrophy to an extent not to completely recover the growth by the addition to a medium containing ordinary amount of the corresponding amino acid. The strain is further subjected to the mutation to release the suppression of biosynthesis of the corresponding amino acid to obtain a microbial strain having improved productivity of the corresponding amino acid. The objective method for breeding an amino acid-producing strain is characterized by the production of the above strain. Isoleucine and valine are produced with E.coli using the above mutant.