초록
<P>Metabolic engineering of<I>Corynebacterium glutamicum</I>has sought to divert carbon into L-isoleucine. However, the fermentation period of this strain is long. The<I>C</I>.<I>glutamicum</I>YILW strain (Leu<SUP>L</SUP>, AHV<SUP>r</SUP>, SG<SUP>r</SUP>, Leu-ME<SUP>r</SUP>) was previously derived by repeated compound mutagenesis which could accumulate 20.2 g/L L-isoleucine in a 5-L jar fermentor. Overexpression of the threonine dehydratase gene (<I>ilv</I>A) from<I>Corynebacterium glutamicum</I>YILW and coexpression of threonine dehydratase and acetolactate synthase (<I>ilv</I>BN) from it were employed to divert carbon flux toward L-isoleucine. The strain<I>E. coli</I>TRFC with the expression of<I>ilv</I>A could accumulate L-isoleucine of 6.8 g/L without accumulation of any L-threonine by fed-batch fermentation in a 5-L jar fermentor. However, the production of L-isoleucine by the strain<I>E</I>.<I>coli</I>TRFC with the co-expression of<I>ilv</I>A and<I>ilv</I>BN was decreased by 19.1%, and the production of L-valine was increased by 40% compared with that of<I>E. coli</I>TRFC with the expression of<I>ilv</I>A.</P>