초록
<P><B>Abstract</B></P><P>Three genes, <I>gnd</I>, <I>pgl</I>, and <I>fbp</I>, relevant to the pentose phosphate pathway (PPP) were overexpressed in <I>Corynebacterium glutamicum</I> IWJ001, leading to increase of l‐isoleucine production. The transcriptional levels of <I>gnd</I>, <I>pgl</I>, and <I>fbp</I> significantly increased in IWJ001/pDXW‐8‐<I>gnd</I>‐<I>fbp</I>‐<I>pgl</I>. Compared with the control strain IWJ001/pDXW‐8, intracellular NADPH/NADP<SUP>+</SUP> ratios in IWJ001/pDXW‐8‐<I>gnd</I> and IWJ001/pDXW‐8‐<I>gnd</I>‐<I>fbp</I> cells grown for 36 H increased threefold and fourfold, respectively, indicating that overexpression of <I>gnd</I> and <I>fbp</I> redirected the carbon flux to PPP. Intracellular NADPH/NADP<SUP>+</SUP> ratio in IWJ001/pDXW‐8‐<I>gnd</I>‐<I>fbp</I>‐<I>pgl</I> grown for 36 H was similar to IWJ001/pDXW‐8, suggesting that the NADPH produced by PPP could be quickly consumed for l‐isoleucine production. 10.9 and 28.96 g/L of l‐isoleucine was produced in IWJ001/pDXW‐8‐<I>gnd</I>‐<I>fbp</I>‐<I>pgl</I> in shake flask cultivation and fed‐batch fermentation, respectively. In addition, IWJ001/pDXW‐8‐<I>gnd</I>‐<I>fbp</I>‐<I>pgl</I> grew fast, its dry cell weight reached 49 g/L after 48 H, whereas the start strain IWJ001/pDXW‐8 reached only 40 g/L. After 96 H fermentation, l‐isoleucine yield on glucose in IWJ001/pDXW‐8‐<I>gnd</I>‐<I>fbp</I>‐<I>pgl</I> reached 0.138 g/g. The results demonstrate that carbon flux redirection to PPP is an efficient approach to enhance l‐isoleucine production in <I>C. glutamicum</I>.</P>