水华蓝藻的膦酸酯类化合物利用能力及其生态功能探究

Cyanobacteria are a group of photosynthetic prokaryotes that found in most eco-systems, and play a significant role in global carbon and nitrogen cycles. Harmful cyanobacteria bloom, formed by a few genera, has become a global concern. Phosphonate is phosphorus that contains C-P bond and was newly found to be microorganism available. And the deciphering of marine bloom-forming Trichodesmium phosphonate utilization has dramatically promote the understanding of cyanobacterial strategy against phosphorus depletion. On the contrary, similar research did not draw enough attention in freshwater, where phosphonate pollutants were demonstrated to be ubiquitous.. Based on re-analysis of genomic and metagenomic data deposited in database, we discovered that phosphonate degrading genes are present in both freshwater cyanobacterial genome and freshwater bloom water samples. In this study, cyanobacteria from Freshwater Algae Culture Collection at the Institute of Hydrobiology (FACHB) will be recruited and have genome sequenced. Phosphonate degrading genes mining with these genomes, accompanied with algal culture experiment will be conducted to investigate the extent and evolution feature of phosphonate degrading ability in freshwater cyanobacteria. Furthermore, the bio-available of phosphonate by bloom water will also be interpreted through molecular ecology approach and field verification to finally illuminate the exact ecological relation of phosphonate with freshwater bloom. This study aims to lay solid foundation for the migration and transformation study of phosphonate pollutant in freshwater eco-systems and, more importantly, to facilitate more comprehensive understanding of freshwater bloom occurrence and dominance.

蓝藻是生物圈中重要的初级生产者，但部分蓝藻种类可形成有害水华，已发展成全球性水环境问题。因此，研究蓝藻水华发生发展机制，具有重要的科学意义。膦酸酯类化合物是一类新近发现的生物可利用磷，其被证实在海洋水华蓝藻磷限制应答中发挥关键作用。作为一类淡水水体中常见的污染物，膦酸酯相关研究在淡水蓝藻中未受到足够重视。. 通过基因组与宏基因组数据比对分析，我们发现膦酸酯利用基因在淡水蓝藻与水华水体中均存在。本项目以前期测序的水生所藻种库近200株蓝藻基因组数据为基础，开展功能基因分析与藻类生理实验，明确膦酸酯利用能力在淡水蓝藻中的分布；通过分子生态学与膦酸酯添加实验，重点关注微囊藻水华水体的膦酸酯可利用性，并结合微囊藻膦酸酯利用机制解析，以期最终阐明膦酸酯在微囊藻水华过程中的生态功能。本研究将为水体膦酸酯类污染物迁移与转化的研究提供理论支持，更将促进对蓝藻水华暴发与优势维持机制的全面理解。

本项目在国家自然科学基金（批准号：31900090）的资助下，紧密围绕水华蓝藻的膦酸酯类化合物利用能力及其生态功能这一核心科学问题开展了一系列深入系统的研究。.首先，我们对蓝藻门膦酸酯代谢功能基因进行了系统的挖掘，确定了5.88%（151/2568）蓝藻编码膦酸酯降解基因簇、3.15%（81/2568）蓝藻藻株具有潜在膦酸酯生物合成能力；说明了蓝藻在膦酸酯的合成与分解代谢过程中均发挥重要作用，并持续贡献于磷的氧化还原循环。同时，我们对蓝藻膦酸酯利用过程的细胞响应进行了追踪，明确了蓝藻膦酸酯利用过程细胞应答与甲烷排放等生态风险。另一方面，由于大部分单细胞蓝藻不编码膦酸酯利用基因元件，我们对这部分蓝藻展开了基于藻菌互作的膦酸酯利用机制研究。基于大量蓝藻的宏基因组数据与野外水体宏转录组数据，我们明确了蓝藻及其藻际细菌群落是水体膦酸酯生物利用的重要驱动力；结合实验室共培养实验，验证了这一过程在微囊藻生长与水华优势维持过程中发挥的重要作用，并提出了基于藻菌互作驱动的膦酸酯生物转化的概念。本研究揭示了膦酸酯的利用在蓝藻水华发生发展过程中的作用，深化对蓝藻水华暴发和优势维持机理的认识。.在本项目实施的三年期间，取得了不错的成绩，以课题负责人赵亮博士为第一作者发表在水环境顶级期刊Water Research发表文章一篇；另一篇文章以课题负责人赵亮博士为第一作者投稿于微生物学顶级期刊Microbiome，目前一审已经完成，目前正积极返修中；申请相关专利一项。本项目还培养多名科研人才，包括硕士生2名，本科生3名。