转录组揭示自养和混合培养栅藻油脂代谢途径差异

Transcriptome reveals differences in lipid metabolism pathways between autotrophic and mixotrophic Desmodesmus sp.

为探讨混合培养条件下栅藻脂质高产的调控机理,对栅藻(Desmodesmus sp.)分别进行自养和混合培养,使用转录组测序对比了Desmodesmus sp.在两种培养方式下油脂代谢途径差异。结果表明,混合培养组上调基因共1081个,下调基因共575个,非显著差异表达基因总共23331个。差异基因GO富集主要在光合作用的分子功能、生物过程和细胞组分上,如类囊体、光系统Ⅰ、叶绿素结合、光合电子传输、光反应和暗反应等。KEGG途径富集最显著的是光合作用,其次为脂肪酸伸长、内质网中的蛋白质加工以及淀粉和蔗糖合成。在混合培养条件下,PSⅡ对光能的需求降低,但光合电子传输增强,产生更多的ATP和NADPH用于光合作用的碳固定和细胞的其它代谢活动。脂质积累的增强主要源于糖酵解途径的增强,为脂肪酸合成产生了更多的乙酰辅酶A,促进了脂肪酸的生成。

To explore the more efficient regulation mechanism of lipid accumulation in Desmodesmus sp. under mixotrophic condition, Desmodesmus sp. were cultivated unde autotrophic and mixotrophic conditions, and differences of lipid accumulation of Desmodesmus sp. under two cultivation conditions were compared using transcriptome sequencing. The results showed that the mixotrophic group had 1081 up-regulated genes, 575 down-regulated genes,and 23 331 non-significantly differentially expressed genes. The enrichment of the differential gene GO term was mainly in the molecular function, biological process and cell components of photosynthesis, such as thylakoid, photosystem Ⅰ, chlorophyll binding, photosynthetic electron transport, light response and dark response etc. The enrichment of KEGG pathway was mainly characterized as photosynthesis, followed by fatty acid elongation, protein processing in the endoplasmic reticulum, and starch and sucrose synthesis. Under mixotrophic condition, reduced PSⅡ′s demand for light energy was reduced, but photosynthetic electron transport was enhanced, and more ATP and NADPH were produced for carbon fixation in photosynthesis and other metabolic activities of cells. The enhancement of lipid accumulation was mainly due to the enhancement of glycolytic pathway, which produced more acetylCoA for fatty acid production and promoting fatty acids production.