欧亚国际

摘要

微藻被认为是高价值脂质和油脂化学物质的生产平台。包括海洋小绿球藻在内的几个物种会产生大量的必需[配方：见正文]-3多不饱和脂肪酸（PUFA），这些脂肪酸是食物和饲料的组成部分，具有促进健康的作用。N.oceanica可以进一步积累高含量的非极性脂质，其化学性质使其成为棕榈油等植物油的潜在替代品。然而，微藻获得的生物量和脂质生产率需要提高才能达到商业可行性。基因工程可以提高生物量和脂质生产率，例如通过增加脂质的碳通量。在此，我们报道了在有利的生长条件下，海洋猪笼草中甘油-3-磷酸酰基转移酶（GPAT）的过度表达，作为增加非极性脂质含量的一种策略。与野生型相比，过度产生靶向内质网的内源性（NoGPAT）或异源（Acutodesmus oblique GPAT）GPAT酶的转化体的非极性脂质含量分别增加了42%和51%。转化株的生物量生产力没有显著受损，导致NoGPAT和AoGPAT转化株的脂质生产力分别提高了37%和42%。当暴露于营养胁迫时，转化体和野生型的脂质含量相似，这表明在有利的生长条件下，GPAT酶对N.oceanica的脂质合成具有很强的通量控制作用。NoGPAT转化体在非极性脂质中进一步积累PUFA，达到每生物量6.8%的PUFA，相对于野生型增加了24%。总之，我们的研究结果表明，GPAT是微藻脂质代谢工程的一个有趣靶点，以改善微藻中非极性脂质和PUFA的积累。

Expression of glycerol-3-phosphate acyltransferase increases non-polar lipid accumulation in Nannochloropsis oceanica

Abstract

Microalgae are considered a suitable production platform for high-value lipids and oleochemicals. Several species including Nannochloropsis oceanica produce large amounts of essential [Formula: see text]-3 polyunsaturated fatty acids (PUFAs) which are integral components of food and feed and have been associated with health-promoting effects. N. oceanica can further accumulate high contents of non-polar lipids with chemical properties that render them a potential replacement for plant oils such as palm oil. However, biomass and lipid productivities obtained with microalgae need to be improved to reach commercial feasibility. Genetic engineering can improve biomass and lipid productivities, for instance by increasing carbon flux to lipids. Here, we report the overexpression of glycerol-3-phosphate acyltransferase (GPAT) in N. oceanica during favorable growth conditions as a strategy to increase non-polar lipid content. Transformants overproducing either an endogenous (NoGPAT) or a heterologous (Acutodesmus obliquus GPAT) GPAT enzyme targeted to the endoplasmic reticulum had up to 42% and 51% increased non-polar lipid contents, respectively, compared to the wild type. Biomass productivities of transformant strains were not substantially impaired, resulting in lipid productivities that were increased by up to 37% and 42% for NoGPAT and AoGPAT transformants, respectively. When exposed to nutrient stress, transformants and wild type had similar lipid contents, suggesting that GPAT enzyme exerts strong flux control on lipid synthesis in N. oceanica under favorable growth conditions. NoGPAT transformants further accumulated PUFAs in non-polar lipids, reaching a total of 6.8% PUFAs per biomass, an increase of 24% relative to the wild type. Overall, our results indicate that GPAT is an interesting target for engineering of lipid metabolism in microalgae, in order to improve non-polar lipid and PUFAs accumulation in microalgae.

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