Chen Qi
1981
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Abstract
ABSTRACT The investigation of L-glutamic acid fermentation was started in our country in 1958. By using Corynebacterium pekinense Chen et al. nov. sp. AS 1.299 and C. crenatum Chen etLi nov. sp. AS 1.542, fermentative production of L-glutamic acid has been established on industrial scale since 1965. L-lysine, L-valine and L-proline also have been produced with various amino acid-requiring mutants derived from C. pekinense. We isolated several mutants resistant to α-amino-β-hydroxyvaleric acid (AHV) and S-2-aminoethyl-L-cysteine (AEC) from C. crenatum and C. pekinense , and fermentative production of L-isoleucine, L-threonine and L-lysine with these resistant mutants respectively were established. We also obtained a new L-phenylalanine-producing mutant of C. crenatum , resistant to p-fluorophenyl-alanine (PFP) and requiring hypoxanthine or xanthine. In addition, a mutant producing a large amount of L-leucine was also stepwisely derived from C. crenatum. The regulation of L-isoleucine biosynthesis in C. crenatum AS 1.542 and its AHV-resistant mutant AS 1.998 were studied preliminarily. KEYWORDS Amino acid fermentation; Corynebacterium pekinense; Corynebacterium crenatum ; breeding; auxotroph; resistant mutant; multiple mutant; feedback regulation; selection and mutation.