破囊壶菌二十二碳六烯酸（DHA）生物合成路径及代谢网络的研究

Docosahexaenoic Acid (DHA) is an essential nutrient for human health and has broad market applications. Thraustochytrids are an abundant source of polyunsaturated fatty acids (PUFAs) and serve as an ideal bioresource for DHA production. It is critical for high-yield DHA production to fully understand DHA biosynthetic pathway and regulatory networks. The Principal Investigator (PI) has made lots of endeavors to study ecological functions of thraustochytrids and to isolate many thraustochytridys strains for their biotechnological potentials. Draft genome maps have been constructed from HiSeq sequence data for 4 thraustochytrid strains of different genera isolated from different marine habitats. Annotation of some polyketide synthase and fatty acid synthase genes has been completed for these strains. This proposed research aims at obtaining their fine genome maps through further PacBio sequence analyses of these genomes. Genome comparison analyses will be used to reveal their basic genomic features and uniqueness of their gene structures for individual DHA biosynthetic pathways. Their transcriptomic analyses will be carried out under different fermentation conditions. DHA biosynthetic pathway and its regulatory networks will be derived from the results of genomic and transcriptomic analyses. The key genes of the biosysthetic pathways and regulatory networks will be confirmed using molecular approaches (e.g., gene knockout). The ultimate goal of this project is to identify DHA biosynthetic pathway, to establish local and global regulation networks, and to understand the mechanism of thraustochytrids DHA biosynthesis for the improved DHA production.

DHA是人体健康不可或缺的营养物质，具有广阔的市场前景。破囊壶菌可产生丰富的不饱和脂肪酸，是生产DHA的理想生物资源。了解破囊壶菌完整的DHA生物合成路径及调控网络是提高其DHA产量的基础。多年来，申请者致力于破囊壶菌的生态学研究和资源的开发，获取了大量破囊壶菌菌株。目前，本项目组已完成了4株不同来源和不同属破囊壶菌基因组的二代测序，利用生物信息学方法完成了其基因组框架图的构建及DHA生物合成相关基因的初步注释。在此基础上，本项目进一步利用单分子测序的结果，构建破囊壶菌基因组精细图，比较不同破囊壶菌基因组，分析破囊壶菌基因组结构的基本特点，详细了解基因组间DHA合成相关基因的异同；综合不同发酵条件下不同破囊壶菌转录组分析结果，预测DHA生物合成路径及其调控网络，并借助分子生物学手段加以验证。本项目旨在明确破囊壶菌DHA生物合成机理及调控网络，为提高其DHA产量提供重要的理论依据。

DHA是人体健康不可或缺的营养物质，具有广阔的市场前景。破囊壶菌可产生丰富的不饱和脂肪酸，是生产DHA的理想生物资源。了解完整的DHA生物合成路径及调控网络是提高其DHA产量的基础。针对不同来源、不同属破囊壶菌的DHA 合成路径及调控网络进行了全面解析。完成了破囊壶菌全基因组精细图，以转录组中DHA 合成相关基因的差异表达情况为基础，确定了DHA合成路径中的关键基因及调控因子。以分子生物学手段，验证了破囊壶菌中DHA的合成路径及其关键基因的调控模式。明确了破囊壶菌DHA 合成路径的基因结构、调控方式及代谢网络。.本项目构建了破囊壶菌的全基因组精细图，并在此基础上确定了DHA的生物合成路径及相关基因的结构特征，完成了破囊壶菌转录组测序及组装。分析了DHA的合成代谢调控机理，验证了关键基因的功能。并对高产DHA的破囊壶菌菌株进行了发酵工艺流程优化，达到了中试发酵水平。