Wax ester and lipophilic compound profiling of Euglena gracilis by gas chromatography-mass spectrometry: toward understanding of wax ester fermentation under hypoxia
Wax ester and lipophilic compound profiling of Euglena gracilis by gas chromatography-mass spectrometry: toward understanding of wax ester fermentation under hypoxia
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DOI：
10.1007/s11306-014-0687-1
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发表时间：
2015-02-01
期刊：
影响因子：
3.6
通讯作者：
Ohta, Daisaku
中科院分区：
文献类型：
--
作者：
Furuhashi, Takeshi;Ogawa, Takumi;Ohta, Daisaku
脂质正越来越多地用作生物柴油原料，并且来自纤细裸藻的几种饱和蜡酯是户外批量生产的候选者。蜡酯发酵在裸藻强烈增加缺氧，但对蜡酯生物合成的代谢转变的关键事件知之甚少。蜡酯和其他亲脂性化合物的分析是研究蜡酯发酵分子机制的第一步，因此，需要一个简单而全面的分析平台。建立了眼虫体内蜡酯和亲脂性化合物的气相色谱-质谱联用分析方法。使用这种方法，我们比较了野生型眼虫Z菌株和漂白SM-ZK菌株之间的蜡酯和亲脂性化合物的积累概况。野生型和漂白菌株均含有C14：0脂肪酸-C14：0脂肪醇作为主要蜡酯。蜡酯发酵在停止供氧后4小时通过停止培养物搅拌开始，导致在24小时期间蜡酯量的线性增加和成比例变化。然而，通过氮气通气的完全缺氧抑制蜡酯的产生，并且碳酸氢盐的添加逆转了抑制，这表明在缺氧下蜡酯发酵需要额外的碳源。我们简单的方法，使调查的代谢反应，导致蜡酯发酵眼虫。
Lipids are being increasingly used as biodiesel feedstock, and several saturated wax esters from Euglena gracilis are candidates for outdoor bulk production. Wax ester fermentation in Euglena is strongly increased by hypoxia, but key events underlying the metabolic shift toward wax ester biosynthesis are poorly understood. Profiling of wax esters and other lipophilic compounds is the first step for research toward the clarification of wax ester fermentation molecular mechanisms, and thus, a simple and comprehensive platform for their profiling is required. In this study, we established a profiling method for wax esters and lipophilic compounds in Euglena using gas chromatography-mass spectrometry (GC-MS). Using this method, we compared accumulation profiles of wax esters and lipophilic compounds between a wild-type Euglena Z strain and a bleached SM-ZK strain. Both the wild-type and the bleached strains contained C14:0 fatty acid-C14:0 fatty alcohol as a dominant wax ester. Wax ester fermentation initiated 4 h after the cessation of oxygen supply by halting the culture agitation resulting in linear increase and proportional changes of wax ester amounts during 24 h. However, complete anoxia by nitrogen gas aeration inhibited wax ester production and the addition of bicarbonates reversed the inhibition, suggesting that there is a need for an additional carbon source for wax ester fermentation under anoxia. Our simple method enables the investigation of metabolic responses leading to wax ester fermentation in Euglena.