Abstract：
Triacylglycerols (TAG) from microalgae can be used as feedstocks for biofuel production to address fuel shortages. Most of the current research has focused on the enzymes involved in TAG biosynthesis. In this study, the effects of malic enzyme (ME), which provides precursor and reducing power for TAG biosynthesis, on biomass and lipid accumulation and its response to salt stress in Dunaliella salina were investigated. The overexpression of DsME1 and DsME2 improved the lipid production, which reached 0.243 and 0.253 g/L and were 30.5 and 36.3% higher than wild type, respectively. The transcript levels of DsME1 and DsME2 increased with increasing salt concentration (0, 1, 2, 3, and 4.5 mol/L NaCl), indicating that DsMEs participated in the salt stress response in D. salina. It was found that cis-acting elements associated with the salt stress response were present on the promoters of two DsMEs. The deletion of the MYB binding site (MBS) on the DsME2 promoter confirmed that MBS drives the expression of DsME2 to participate in osmotic regulation in D. salina. In conclusion, MEs are the critical enzymes that play pivotal roles in lipid accumulation and osmotic regulation.
摘要：
来自微藻的三酰基甘油(TAG)可用作生物燃料生产的原料以解决燃料短缺问题。目前的研究大多集中在TAG生物合成中涉及的酶。在这项研究中,苹果酸酶（ME）的作用，为TAG生物合成提供前体和还原能力，研究了盐藻生物量和脂质积累及其对盐胁迫的响应。DsME1和DsME2的过表达改善了脂质的产生,分别达到0.243和0.253g/L，比野生型高30.5和36.3%，分别。DsME1和DsME2的转录水平随着盐浓度（0、1、2、3和4.5mol/LNaCl）的增加而增加，表明DsME参与了盐藻的盐胁迫反应。发现与盐胁迫响应相关的顺式作用元件存在于两个DsME的启动子上。DsME2启动子上MYB结合位点(MBS)的缺失证实了MBS驱动DsME2的表达参与D.salina的渗透调节。总之,MEs是在脂质积累和渗透调节中起关键作用的关键酶。
