Transcriptomics-based gene discovery and pathway reconstruction of value-added metabolites in the microalgae Dunaliella tertiolecta

Microalgae derived biofuel feedstock stands as a feasible candidate to decrease the burden of oil demand. High photosynthetic efficiency, growth rate, and lipid content are among the several advantages, however, production costs related to large-scale cultivation and down-stream applications still precedes the usage of microalgae-based biofuels efficiently. To decrease the costs related to biofuel reduction, production of value-added metabolites could be coupled to utilization of microalgae feedstock. In this study, we incorporate the power of next-generation DNA sequencing based transcriptomics to identify the key genes of importance responsible for the biosynthesis of several value-added metabolites including ß-carotene, vitamins C and E, and phytosterols produced in non-model microalgae Dunaliella tertiolecta. Our approach well defined the transcriptome of D. tertiolecta relying on cDNA libraries generated and sequenced; resulting in 42,341 unique sequences and 77 transcripts encoding for biosynthesis of ß-carotene, vitamins C and E, and phytosterols. Results will provide basis for metabolic engineering of biosynthetic pathways and gene manupulation applicable in biotechnological production of these value-added metabolites.

微藻源生物燃料原料是缓解石油需求压力的可行候选方案。该类原料具备光合效率高、生长速度快、脂质含量高等多重优势，但大规模培养与下游应用相关的生产成本，仍是高效利用微藻基生物燃料的主要瓶颈。为降低生物燃料生产相关成本，可将高附加值代谢产物的生产与微藻原料的开发利用相结合。本研究借助基于新一代DNA测序（next-generation DNA sequencing）的转录组学（transcriptomics）技术，对非模式微藻三角杜氏藻（Dunaliella tertiolecta）中合成多种高附加值代谢产物的关键功能基因进行鉴定，这些代谢产物包括β-胡萝卜素、维生素C、维生素E及植物甾醇。本研究通过构建并测序cDNA文库，完成了三角杜氏藻的转录组注释，共得到42341条独特序列，其中77条转录本参与编码β-胡萝卜素、维生素C、维生素E及植物甾醇的生物合成途径。本研究结果可为上述高附加值代谢产物的生物技术生产提供代谢通路工程改造与基因操作的理论基础。