Salinity induces unique changes in lipid classes and fatty acids of the estuarine haptophyte <i>Diacronema vlkianum</i>

Studies on the influence of salinity on microalgal lipids have focused mainly on chlorophyte species and knowledge about photosynthetic secondary endosymbionts is limited. Haptophytes exemplify this situation and represent an interesting model to advance knowledge about the high phylogenetic variability of microalgae in their response to salinity. The estuarine Pavlovophyceae <i>Diacronema vlkianum</i> underwent particular lipid class and fatty acid changes under the effect of salinity. Variability due to salinity was higher in the fatty acid profile compared with that of the lipid class profile. Triacylglycerols decreased with salinity in actively growing cells and increased only when salinity rose to 50 and cell growth ceased. Hypersalinity caused a slight, although significant, sulpholipid decrease and a 4-fold increase in phosphatidylglycerol, suggesting a key role for this phospholipid in salt tolerance. Conversely, the betaine lipid diacylglycerol hydroxymethyl-N,N,N-trimethyl-β-alanine was specifically decreased with high salinity. The fatty acids that decreased the most with salinity were 14:0, 16:1n-7, 20:4n-6, 20:5n-3 and 22:6n-3, while higher levels of 16:1n-9, 17:1, 18:2n-6 and 18:3n-3 were induced by high salinity. Despite fatty acid changes, the unsaturation index did not vary with salinity, but nutritional value of <i>D. vlkianum</i> decreased at a salinity of 50 due to a lower presence of 20-C polyunsaturated fatty acids. This pattern of lipid variation in <i>D. vlkianum</i> with salinity has not been described in any other microalgae. Although <i>D. vlkianum</i> grows within a wide salinity range, production of nutritional and functional lipids is more favourable at low salinity values.

关于盐度对微藻（microalgae）脂质的影响的研究多集中于绿藻门（chlorophyte）物种，而针对光合次生内共生体（photosynthetic secondary endosymbionts）的相关认知仍较为有限。定鞭藻类（Haptophytes）正是这一研究现状的典型代表，其作为极具研究价值的模型生物，有助于推动学界对微藻响应盐度的高度系统发育多样性的认知。河口帕夫藻纲（Pavlovophyceae）的*Diacronema vlkianum*在盐度胁迫下，其脂质组分与脂肪酸谱均发生了特异性变化。相较于脂质组分谱，盐度对脂肪酸谱的影响波动更为显著。在活跃生长的细胞中，三酰甘油（Triacylglycerols）含量随盐度升高而降低，仅当盐度升至50且细胞生长停滞时才会出现上升。高盐胁迫会导致硫脂（sulpholipid）出现小幅但显著的下降，同时使磷脂酰甘油（phosphatidylglycerol）含量提升4倍，这表明该磷脂在耐盐性中发挥关键作用。反之，甜菜碱脂类——二酰甘油羟甲基-N,N,N-三甲基-β-丙氨酸（diacylglycerol hydroxymethyl-N,N,N-trimethyl-β-alanine）在高盐环境下特异性降低。随盐度升高降幅最显著的脂肪酸为14:0、16:1n-7、20:4n-6、20:5n-3及22:6n-3；而高盐胁迫则会诱导16:1n-9、17:1、18:2n-6与18:3n-3的含量上升。尽管脂肪酸组成发生变化，*D. vlkianum*的不饱和指数（unsaturation index）并未随盐度改变，但当盐度升至50时，由于20碳多不饱和脂肪酸（polyunsaturated fatty acids）占比降低，其营养价值有所下降。这种盐度诱导的*D. vlkianum*脂质变化模式尚未在其他微藻中被报道过。尽管*D. vlkianum*可在较宽的盐度范围内生长，但在低盐度条件下更利于其营养与功能脂质的合成积累。

搜集汇总

背景与挑战

背景概述

该数据集研究了盐度对河口金藻Diacronema vlkianum脂质类别和脂肪酸的影响，揭示了盐度引起的独特变化模式，如三酰甘油酯减少和磷脂酰甘油增加，这些变化在其他微藻中未见描述。研究发现，尽管D. vlkianum能在宽盐度范围内生长，但低盐度条件更有利于生产具有营养和功能价值的脂质。