中文摘要：

代谢通量分布分析已经成为研究发酵过程特性的有效方法。今建立了花生四烯酸（从）在高山被孢霉ME-1（Mortierella alpina ME-1）体内合成的代谢通量模型，求解不同氮源浓度下发酵各时期的碳流分布。充足氮源发酵时，指数生长期、减速期、稳定期流向AA的碳流分别占总碳流的3．28％，8．80％，6．97％。而通过限制性氮源发酵并在96h补加0．05％的NaNO3成功地引导了发酵碳流迁移，将各时期流向AA的碳流提高至3．95％，19．21％，39．29％，并最终实现AA产量从1.3g·L^-1提高到3．5g·L^-1。这些结果表明限制性氮源发酵并在稳定期补加低浓度的氮源能显著提高AA产量。

英文摘要：

Analysis of flux distributions in metabolic networks has become an important approach for understanding the fermentation characteristics of the process. A model of metabolic flux analysis of arachidonic acid （AA） synthesis in Mortierella alpina ME-1 was established and carbon flux distributions were estimated in different fermentation phases with different concentrations of N-source. During exponential, decelerating and stationary phase, carbon fluxes to AA are 3.28%, 8.80%, 6.97%, respectively, with sufficient N-source broth based on the flux of glucose uptake, and those are increased to 3.95%, 19.21% and 39.29%, respectively, by regulating the shifts of carbon fluxes via fermentation with limited N-source broth and adding 0.05% NaNO3 at 96h. Eventually AA yield increased from 1.3 g·L^-1 to 3.5 g·L^-1. These results suggest a way to improve AA fermentation, that is, fermentation with limited N-source broth and adding low concentration N-source during stationary phase.