Lipid accumulation and metabolic analysis based on transcriptome sequencing of filamentous oleaginous microalgae Tribonema minus at different growth phases.

Filamentous oleaginous microalgae specie Tribonema minus is a promising feedstock for biodiesel production. However, the metabolic mechanism of lipid production in this filamentous microalgal specie remains unclear. Here, we compared the lipid accumulation of T. minus at different growth phases, and described the de novo transcriptome sequencing and assembly and identified important pathways and genes involved in TAG production. Total lipid increased by 2.5-fold and its TAG level in total lipid reached 81.1% at stationary phase. Using the genes involved in the lipid metabolism, the TAG biosynthesis pathways were generated. Moreover, results also demonstrated that, in addition to the observed overexpression of the fatty acid synthesis pathway, TAG production at stationary growth phase was bolstered by repression of the β-oxidation pathway, up-regulation of genes that funnels acetyl-CoA to lipid biosynthesis, especially gene encoding for phospholipid:diacylglycerol acyltransferase (PDAT) which funnels DAG to TAG biosynthesis.