Construction of an L-Isoleucine Overproducing Strain of Escherichia coli K-12

概要

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The genes for a threonine deaminase that is resistant to feedback inhibition by L-isoleucine and for an active aceto-hydroxyacid synthase II were introduced by a plasmid into a L-threonine-producing recombinant strain of Escherichia coli K-12. Analysis of culture broth of the strain using ^<13>C nuclear magnetic resonance suggested that α, β-dihydroxy-β-methylvalerate (DHMV) and α-keto-β-methylvalerate (KMV), the third and the fourth intermediates in the L-isoleucine biosynthetic pathway from L-threonine, respectively, accumulated in the medium in amounts comparable to that of L-isoleucine. The ratio of accumulated L-isoleucine : DHMV : KMV were approximately 2 : 1 : 1. The concentration of accumulated L-isoleucine increased by twofold after the additional introduction of the genes for dihyroxyacid dehydratase (DH) and transaminase-B (TA-B), and the intermediates no longer accumulated. The resultant strain TVD5 accumulated 10 g/l of L-isoleucine from 40 g/l of glucose.
社団法人日本農芸化学会の論文
1999-04-23