Screening of l-Isoleucine Producers among Ethionine Resistant Mutants of l-Threonine Producing Bacteria |
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Authors: | Shigeho Ikeda Itsuo Fujita Fumihiro Yoshinaga |
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Institution: | Central Research Laboratories of Ajinomoto Co., Inc., Kawasaki, Japan |
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Abstract: | Two types of l-isoleucine producing mutants were derived from l-threonine producers by the supplement of the resistance to ethionine.Main control site in l-isoleucine biosynthetic pathway after threonine is threonine dehydratase. In case of Brevibacterium flavum No. 14083, l-isoleucine production was based on the insensitiveness of this key enzyme to feedback inhibition by l-isoleucine. As regards Brevibacterium flavum No. 168, it was based on the increase in the specific activity of this enzyme.The former produced 11.3 g/liter of l-isoleucine and the latter produced 9.92 g/liter from glucose. The former showed a vigorous ability of acetic acid assimilation, but the latter did not. |
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Keywords: | lactic acid bacteria fish probiotics mucus adhesion in vivo colonization |
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