Yarrowia lipolytica is an industrial yeast that can convert waste oil to value-added products. However, it is unclear how this yeast metabolizes lipid feedstocks, specifically triacylglycerol (TAG) substrates. This study used 13C-metabolic flux analysis (13C-MFA), genome-scale modeling, and transcriptomics analyses to investigate Y. lipolytica W29 growth with oleic acid, glycerol, and glucose. Transcriptomics data were used to guide 13C-MFA model construction and to validate the 13C-MFA results. The 13C-MFA data were then used to constrain a genome-scale model (GSM), which predicted Y. lipolytica fluxes, cofactor balance, and theoretical yields of terpene products. The three data sources provided new insights into cellular regulation during catabolism of glycerol and fatty acid components of TAG substrates, and how their consumption routes differ from glucose catabolism. We found that (1) over 80% of acetyl-CoA from oleic acid is processed through the glyoxylate shunt, a pathway that generates less CO2 compared to the TCA cycle, (2) the carnitine shuttle is a key regulator of the cytosolic acetyl-CoA pool in oleic acid and glycerol cultures, (3) the oxidative pentose phosphate pathway and mannitol cycle are key routes for NADPH generation, (4) the mannitol cycle and alternative oxidase activity help balance excess NADH generated from β-oxidation of oleic acid, and (5) asymmetrical gene expressions and GSM simulations of enzyme usage suggest an increased metabolic burden for oleic acid catabolism.

中文翻译：

---

解散耶罗菌中三酰基甘油分解代谢的阐明：细胞如何平衡乙酰辅酶 A 和过量的还原当量


Yarrowia lipolytica 是一种工业酵母，可以将废油转化为增值产品。然而，目前尚不清楚这种酵母如何代谢脂质原料，特别是三酰甘油 （TAG） 底物。本研究使用 13C-代谢通量分析 （13C-MFA） 、基因组规模建模和转录组学分析来研究油脂酸、甘油和葡萄糖对脂肪分解耶尔杆菌 W29 的生长。转录组学数据用于指导 13C-MFA 模型构建并验证 13C-MFA 结果。然后使用 13C-MFA 数据来约束基因组规模模型 （GSM），该模型预测 Y. lipolytica 通量、辅因子平衡和萜烯产物的理论产量。这三个数据源为甘油和 TAG 底物的脂肪酸成分分解代谢过程中的细胞调节以及它们的消耗途径与葡萄糖分解代谢有何不同提供了新的见解。我们发现 （1） 来自油酸的超过 80% 的乙酰辅酶 A 是通过乙醛酸盐分流加工的，与 TCA 循环相比，这种途径产生的 CO2 更少，（2） 肉碱穿梭是油酸和甘油培养物中胞质乙酰辅酶 A 库的关键调节因子，（3） 氧化磷酸戊糖途径和甘露醇循环是 NADPH 产生的关键途径， （4） 甘露醇循环和替代氧化酶活性有助于平衡油酸β氧化产生的过量 NADH，以及 （5） 不对称基因表达和酶使用的 GSM 模拟表明油酸分解代谢的代谢负担增加。