水圈固碳固氮主要生产者蓝藻碳氮元素循环的耦合调控

蓝藻是最重要的初级生产者，它可通过光合作用将空气中的CO2固定为有机物，此外许多蓝藻还能固氮。蓝藻生物量主要存在于水环境，其固定的CN通过食物链扩散到水体生态系统，因而蓝藻为水圈CN元素循环提供了原初推动力。这种推动力在微观上表现为蓝藻细胞中的碳氮代谢耦合过程。由于高效碳氮耦合蓝藻细胞根据环境碳氮水平的波动迅速调整胞内碳氮代谢活性以维持细胞内碳氮代谢的平衡及碳氮比。因此，探究蓝藻CN耦合调控机制对阐明其驱动水圈环境中碳氮元素循环机理具有重要意义。本项目拟以淡水固氮蓝藻Anabaena PCC7120为模型研究碳氮代谢网络调控，阐明蓝藻碳氮耦合调控机制。综合代谢组学、转录组学、遗传学、结构生物学等多学科研究手段，我们将揭示蓝藻碳氮代谢调控网络，并建立其响应环境变化并协调碳氮耦合-平衡分子机制模型。本研究将促进对水圈微生物在地球元素循环中作用的综合认知，为应对全球变化、保护水圈生态提供科学依据

As one of the most important primary producers, Cyanobacteria can transform CO2 to organic matter through oxygen-producing photosynthesis, and many of them are also capable of biological nitrogen fixation. Most cyanobacterial biomass exists in the aquatic environment, and the fixed carbon (C) and nitrogen (N) propel the development of the aquatic ecosystems through the food chain. Thus, cyanobacteria provide the original driving force for the CN cycle in aquatic biospheres, and in particular because of the carbon-nitrogen metabolic coupling mechanism in cyanobacterial cells. To achieve efficient carbon-nitrogen coupling, cyanobacterial cells must be able to adjust rapidly intracellular C and N metabolic activities according to the fluctuations of C/N availability in the environment. Therefore, to understand the mechanism of CN cycle in aquatic biosphere, it is crucial to explore the regulation mechanism of CN coupling in cyanobacteria. In this project, we aim to study the regulation of carbon and nitrogen metabolic network using the model freshwater N2-fixing cyanobacterium Anabaena PCC 7120, and to deepen our understanding on the N/C coupling and C/N ratio mechanism. Combining multidisciplinary research methods such as metabolomics, transcriptomics, genetics, and structural biology, we aim to reveal the regulation network of CN metabolism of cyanobacteria, and establish a molecular model on how these organisms respond to environmental changes and balance CN metabolism accordingly. This study will expand our knowledge on the role of aquatic microorganisms in the elementary cycle on the Earth, and provide a scientific basis for dealing with global changes and protecting aquatic biospheres.