During the pentose phosphate pathway (PPP), two important components, NADPH and pentoses, are provided to the cell. Previously it was shown that this metabolic pathway is a source of reducing agent for lipid synthesis from glucose in the yeast Yarrowia lipolytica. Y. lipolytica is an attractive microbial host since it is able to convert untypical feedstocks, such as glycerol, into oils, which subsequently can be transesterified to biodiesel. However, the lipogenesis process is a complex phenomenon, and it still remains unknown which genes from the PPP are involved in lipid synthesis. To address this problem we overexpressed five genes from this metabolic pathway: transaldolase (TAL1, YALI0F15587g), transketolase (TKL1, YALI0E06479g), ribulose-phosphate 3-epimerase (RPE1, YALI0C11880g) and two dehydrogenases, NADP+-dependent glucose-6-phosphate dehydrogenase (ZWF1, YALI0E22649g) and NADP+-dependent 6-phosphogluconate dehydrogenase (GND1, YALI0B15598g), simultaneously with diacylglycerol acyltransferase (DGA1, YALI0E32769g) and verified each resulting strain’s ability to synthesize fatty acid growing on both glycerol and glucose as a carbon source. Our results showed that co-expression of DGA1 and TKL1 results in higher SCO synthesis, increasing lipid content by 40% over the control strain (DGA1 overexpression). Simultaneous overexpression of DGA1 and TKL1 genes results in a higher lipid titer independently from the fermentation conditions, such as carbon source, pH and YE supplementation.

中文翻译：

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转酮酶对酵母解脂耶氏酵母中脂质生物合成的影响。

在磷酸戊糖途径（PPP）中，向细胞提供了两个重要成分，NADPH和戊糖。先前已证明该代谢途径是酵母解脂耶氏酵母中葡萄糖合成脂质的还原剂来源。解脂耶氏酵母是一种有吸引力的微生物宿主，因为它能够将非典型原料（如甘油）转化为油，然后可以将其酯交换为生物柴油。然而，脂肪形成过程是一个复杂的现象，并且仍然不清楚来自PPP的哪些基因参与脂质合成。为解决此问题，我们从该代谢途径中过表达了5个基因：转醛缩酶（TAL1，YALI0F15587g），转酮醇酶（TKL1，YALI0E06479g），核糖磷酸3-表异构酶（RPE1，YALI0C11880g）和两个脱氢酶，NADP +依赖性葡萄糖6磷酸葡萄糖脱氢酶（ZWF1，YALI0E22649g）和NADP +依赖性6磷酸葡萄糖酸酯脱氢酶（GND1，YALI0B15598g），同时与二酰基甘油酰基转移酶（DGA1，YALI0E32769g）同时验证了每种菌株在脂肪酸生长时合成脂肪酸生长的能力甘油和葡萄糖为碳源。我们的结果表明，DGA1和TKL1的共表达可导致更高的SCO合成，使脂质含量比对照菌株增加40％（DGA1过表达）。DGA1和TKL1基因的同时过表达导致更高的脂质效价，而与发酵条件无关，例如碳源，pH和YE补充。YALI0E32769g），并验证了每个菌株在甘油和葡萄糖（作为碳源）上合成脂肪酸的能力。我们的结果表明，DGA1和TKL1的共表达可导致更高的SCO合成，使脂质含量比对照菌株增加40％（DGA1过表达）。DGA1和TKL1基因的同时过表达导致更高的脂质效价，而与发酵条件无关，例如碳源，pH和YE补充。（YALI0E32769g），并验证了每个所得菌株合成甘油和葡萄糖作为碳源时生长的脂肪酸的能力。我们的结果表明，DGA1和TKL1的共表达可导致更高的SCO合成，使脂质含量比对照菌株增加40％（DGA1过表达）。DGA1和TKL1基因的同时过度表达导致更高的脂质效价，而与发酵条件无关，例如碳源，pH和YE补充。