Zhang Huaiyuan, Wu Chao, Wu Qingyu, Dai Junbiao, Song Yuanda
Colin Ratledge Center for Microbial Lipids, School of Agricultural Engineering and Food Science, Shandong University of Technology, Zibo, 255049, Shandong, People's Republic of China.
School of Food Science and Technology, Jiangnan University, Wuxi, 214122, Jiangsu, People's Republic of China.
PLoS One. 2016 Jul 25;11(7):e0159187. doi: 10.1371/journal.pone.0159187. eCollection 2016.
The oleaginous yeast Yarrowia lipolytica has considerable potential for producing single cell oil, which can be converted to biodiesel, a sustainable alternative to fossil fuels. However, extensive fundamental and engineering efforts must be carried out before commercialized production become cost-effective. Therefore, in this study, metabolic flux analysis of Y. lipolytica was performed using 13C-labeled glucose as a sole carbon source in nitrogen sufficient and insufficient media. The nitrogen limited medium inhibited cell growth while promoting lipid accumulation (from 8.7% of their biomass to 14.3%). Metabolic flux analysis showed that flux through the pentose phosphate pathway was not significantly regulated by nitrogen concentration, suggesting that NADPH generation is not the limiting factor for lipid accumulation in Y. lipolytica. Furthermore, metabolic flux through malic enzyme was undetectable, confirming its non-regulatory role in lipid accumulation in this yeast. Nitrogen limitation significantly increased flux through ATP:citrate lyase (ACL), implying that ACL plays a key role in providing acetyl-CoA for lipid accumulation in Y. lipolytica.
产油酵母解脂耶氏酵母在生产单细胞油方面具有巨大潜力，这种单细胞油可转化为生物柴油，是化石燃料的一种可持续替代品。然而，在商业化生产变得具有成本效益之前，必须进行大量的基础和工程研究。因此，在本研究中，以13C标记的葡萄糖作为唯一碳源，在氮充足和氮不足的培养基中对解脂耶氏酵母进行了代谢通量分析。氮限制培养基抑制细胞生长，同时促进脂质积累（从其生物量的8.7%增加到14.3%）。代谢通量分析表明，磷酸戊糖途径的通量不受氮浓度的显著调节，这表明NADPH的产生不是解脂耶氏酵母脂质积累的限制因素。此外，未检测到通过苹果酸酶的代谢通量，证实了其在该酵母脂质积累中不起调节作用。氮限制显著增加了通过ATP：柠檬酸裂解酶（ACL）的通量，这意味着ACL在为解脂耶氏酵母脂质积累提供乙酰辅酶A方面起关键作用。
