초록
<P><B>Abstract</B></P> <P>Erythritol is a new polyol used as a bulk sweetener in food industries, and the bioconversion of agricultural or industrial wastes to erythritol by <I>Yarrowia lipolytica</I> at high productivity is of great cost-effectiveness. In the <I>Yarrowia</I>-erythritol procedure, erythritol synthesis is triggered only under nitrogen starvation condition (or a high carbon-to-nitrogen ratio, C/N), causing an inefficient product yield and the unavailability of nitrogen-rich wastes. Sucrose non-fermenting protein kinase (Snf1) plays an important role in the nitrogen starvation-triggered process. In this study, a Snf1-deficient strain <I>Y. lipolytica</I> M53-S was obtained, and the calculated carbon source uptake (<I>Q</I> <SUB>s</SUB>) and erythritol formation (<I>Q</I> <SUB>Ery</SUB>) rates were respectively increased by 46% and 49% when a lower C/N ratio of 20/1 was imposed on M53-S cells than that during nitrogen limitation (C/N=250/1). Moreover, loss of Snf1 abolished the reliance on high osmotic pressure and supplemental nutrition. Results of qRT-PCR suggested that the metabolic enzymes in M53-S were u P-R egulated at transcriptional level under low C/N ratio. The increased enzyme activitiesf also suggested a carbon overflow into the erythritol biosynthetic pathway. During the scaled-up fermentation process, 72.5g/L of erythritol was produced by M53-S within a greatly shortened period. This work confirms the critical role of Snf1 in coupling between nitrogen starvation and product synthesis, which also presents a new perspective in developing a cost-effective process for efficient production of secondary metabolites from nitrogen-rich wastes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Snf1-deficient strain M53-S was constructed for efficient erythritol production. </LI> <LI> Erythritol productivity of M53-S was enhanced under nitrogen-enriched condition. </LI> <LI> 72.5g/L erythritol was achieved via scale-up cultivation in a shortened period. </LI> <LI> Potential application of nitrogen-rich wastes in erythritol production is promoted. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>