氮元素对三角褐指藻岩藻黄素和油脂合成关键酶基因表达与代谢合成的影响

为阐明氮元素对微藻次生代谢积累和调控的影响,以三角褐指藻为试验材料,研究不同氮浓度896(CK)、448、112、28和0 μmol·L^-1]处理对三角褐指藻细胞生长、岩藻黄素含量、油脂含量以及叶绿素a含量的影响,并对岩藻黄素-叶绿素蛋白复合体基因(FCPb)和酰基-酰基载体蛋白去饱和酶基因(FAB2)的表达进行实时荧光定量PCR分析。结果表明,氮限制极显著抑制了三角褐指藻细胞的生长和岩藻黄素的合成,但促进了油脂的合成。当氮浓度为112 μmol·L^-1时,三角褐指藻岩藻黄素含量最低(0.084 mg·g^-1DW),而油脂含量最高,较CK提高了1.36倍。叶绿素a与岩藻黄素含量变化趋势一致。相关性分析表明,氮限制条件下,三角褐指藻岩藻黄素含量与油脂含量显著相关(R²=0.998 8)。实时荧光定量PCR分析表明,氮限制抑制了三角褐指藻中FCPb的表达,促进了FAB2的表达。综上,氮限制通过调控三角褐指藻岩藻黄素、油脂生物合成途径相关基因的表达影响了岩藻黄素和油脂的积累。本研究为进一步探究岩藻黄素与脂类物质代谢合成的关联性提供了一定的理论参考。

Effects of Nitrogen on the Gene Expression and Metabolic Biosynthesis of Fucoxanthin and Lipid in Phaeodactylum tricornutum

To demonstrate the effects of nitrogen on secondary metabolic accumulation and regulation of microalgae. The effect of different nitrogen concentrations on the growth, fucoxanthin, lipid and chlorophyll a of Phaeodactylum tricornutum was studied. The expression of fucoxanthin-chlorophyll protein complex gene (FCPb) and acyl-ACP desaturase gene (FAB2) were examined by real-time quantitive PCR (RT-qPCR). The results showed that nitrogen limitation reduced the growth of P. tricornutum cells and inhibited the synthesis of fucoxanthin in P. tricornutum, while it promoted the synthesis of lipid. When the nitrogen concentration was reached to 112 μmol·L^-1, the fucoxanthin content was the lowest (only 0.084 mg·g^-1DW^-1), while the lipid content was the highest and it was 1.37 times higher than that of the control group. The chlorophyll a content was consistent with the change rhythm of fucoxanthin content. Correlation analysis showed that under nitrogen limitation, the fucoxanthin content of P. tricornutum was significantly correlated with the relative content of lipid (R²=0.998 8). Nitrogen limitation inhibited the expression of FCPb in P. tricornutum, and promoted the expression of FAB2 in P. tricornutum. These findings indicate that nitrogen limitation affects fucoxanthin and total lipid accumulation by regulating the expression of fucoxanthin and lipid biosynthesis pathway-related genes in P. tricornutum. The results provide a theoretical reference for further exploring the correlation between fucoxanthin and lipid metabolism and synthesis.