l-Isoleucine Production by Analog-resistant Mutants Derived from Threonine-producing Strain of Corynebacterium glutamicum |
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Authors: | Hiroshi Kase Kiyoshi Nakayama |
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Institution: | Tokyo Research Laboratory, Kyowa Hakko Kogyo Co., Ltd., Machida-shi, Tokyo |
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Abstract: | A thiaisoleucine-resistant mutant, ASAT–372, derived from a threonine producer of Corynebacterium glutamicum, KY 10501, produced 5 mg/ml each of l-isoleucine and l-threonine. l-Isoleucine productivity of ASAT–372 was improved stepwise, with concurrent decrease in threonine production, by successively endowing it with resistivity to such substances as ethionine, 4-azaleucine and α-aminobutyric acid. The mutant strain finally selected, RAM–83, produced 9.7 mg/ml of l-isoleucine with a medium containing 10% (as sugar) molasses.l-Isoleucine production was significantly affected by the concentration of ammonium sulfate in the fermentation medium. At 4% ammonium sulfate l-isoleucine production was enhanced whereas l-threonine production was suppressed. At 2% ammonium sulfate l-threonine production was stimulated while l-isoleucine production decreased. |
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Keywords: | volatile thiols yeast soy sauce fermentation formation |
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