초록
<P><B>Abstract</B></P><P>Recombinant <I>Saccharomyces cerevisiae</I> expressing exogenous carotenogenic genes can synthesize carotenoids. NADPH is a key cofactor for carotenoid biosynthesis, while glucose‐6‐phosphate dehydrogenase (Zwf1) and an NADH kinase (Pos5) are the two main NADPH‐supplying sources in <I>S</I>.？<I>cerevisiae</I>. Here, the effect of <I>ZWF1</I> and <I>POS5</I> overexpression on carotenoid yield in recombinant <I>S</I>.？<I>cerevisiae</I> was explored. The initial carotenogenic strain Sc‐EYBIH+I which expressed <I>crtE</I>,<I> crtYB</I>,<I> crtI</I>,<I> cHMG1</I> and another copy of <I>crtI</I> could synthesize 1·35？±？0·13？mg？l<SUP>−1</SUP> of lycopene and 0·32？±？0·02？mg？l<SUP>−1</SUP> of <I>β</I>‐carotene. When <I>ZWF1</I> was overexpressed (Sc‐EYBIZH+I), glucose‐6‐phosphate dehydrogenase activity increased by 103‐fold, the transcription level of <I>crtE</I> and <I>crtI</I> increased significantly, the lycopene and <I>β</I>‐carotene yield increased to 2·29？±？0·06 and 0·38？±？0·02？mg？l<SUP>−1</SUP> respectively. When <I>POS5</I> was overexpressed (Sc‐EYBIPH+I), NAD kinase activity increased by 5·5‐fold, the transcription level of <I>crtE</I>,<I> crtYB</I> and <I>crtI</I> increased obviously, the lycopene and <I>β</I>‐carotene yield increased to 2·50？±？0·11 and 0·53？±？0·03？mg？l<SUP>−1</SUP> respectively. Therefore, improvement of NADPH supply contributed to carotenoids biosynthesis in <I>S</I>.？<I>cerevisiae</I> and overexpression of <I>POS5</I> was more effective than overexpression of <I>ZWF1</I>. This study provides a new strategy for enhancing carotenoid biosynthesis.</P><P><B>Significance and Impact of the Study</B></P><P>NADPH is a key cofactor for carotenoid biosynthesis. Glucose‐6‐phosphate dehydrogenase (Zwf1) and an NADH kinase (Pos5) are effective NADPH‐supplying sources in <I>Saccharomyces cerevisiae</I>. When <I>ZWF1</I> and <I>POS5</I> were overexpressed in a carotenoid‐producing <I>S</I>.？<I>cerevisiae</I> strain individually, the total yield of lycopene and <I>β</I>‐carotene increased by 59·9% and 81·4%, respectively, and the final product <I>β</I>‐carotene yield increased by 18·8% and 65·6% respectively. This suggests the improvement of NADPH supply as a useful strategy for carotenoids biosynthesis.</P>