Molecular Dissection of Lipid Biosynthetic Machinery in Green Algae Scenedesmus Species

Abstract

Microalgal species are the most suitable feedstocks for biodiesel production. Though, to commercially utilizing the microalgae for biodiesel production, selection of strains with fast growth rate and high lipid content is required. Scenedesmus species are freshwater microalgae considered for obtaining biodiesel due to their high lipid content and appropriate fatty acid profile. Previous molecular studies on governing storage lipid biosynthesis in microalgae were focused on environmental stress conditions. However, there is no report on the identification of genetic factors responsible for the differential lipid accumulation among different species and strains of microalgae. The current study therefore investigated: 1) Cloning and expression analysis of genes involved in lipid biosynthesis vis-à-vis lipid content in Scenedesmus species 2) Deciphering molecular components channeling precursors to differential lipid accumulation and its regulation in Scenedesmus species. newlineIdentification of fatty acid and triacylglycerol biosynthetic genes was done through comparative genomics and transcriptomics in Scenedesmus dimorphus and the gene expression investigation was performed in various developmental stages and unfavorable conditions in Scenedesmus quadricauda and Scenedesmus dimorphus. Most FA and TAG biosynthesis genes exhibited up-regulation under stress conditions and at late stationary phase, which indicates that multiple genes are involved in regulating the lipid content in Scenedesmus strains. Comparing the results of RT-qPCR analysis from differential conditions discovered six key genes i.e. and#946;-ketoacyl-ACP synthase II (KASII), acyl carrier protein (ACP), fatty acyl-ACP thioestrase (FATA), phosphatidic acid phosphatase (PAP), lysophosphatidic acid acyltransferase (LPAAT) and diacylglycerol acyltransferase (DGAT) that showed correlation with lipid content in all three strains and all conditions. Comparative transcriptomic analysis of Scenedesmus quadricauda and Scenedesmus dimorphus having variable lipid content.