S60: Next-generation sequencing applications for the development of strain-improvement strategies in unsequenced oleaginous microalgae

Microalgae are currently being intensively explored as potential biofuels production platforms due to their ability to accumulate high levels of lipids and favorable growth requirements and characteristics compared to conventional terrestrial bioenergy crops. However, the knowledgebase to define the mechanisms that trigger and control algal lipid biosynthesis and accumulation remains incomplete. Despite identification of over 40,000 microalgal species, to date fewer than 12 eukaryotic microalgae genomes have been sequenced. This dearth of genomic sequence data limits both our understanding of lipid-accumulation mechanisms in microalgae as well as strain-engineering strategies that target enhanced growth rates and productivity. In order to bypass the necessity for genomic sequence data, we have applied next-generation sequencing technologies for de novo transcriptome assembly of the oleaginous microalga, Chlorella vulgaris, under low- and high-lipid accumulation states induced by nitrogen deprivation. The resultant transcriptome identified a number of nitrogen deprivation-responsive transcripts and facilitated complementary proteomic analysis. Combined, these omic platforms have identified targets for strain-improvement strategies and provided insight into the level(s) of regulation governing lipid accumulation in C. vulgaris.