光谱调控强化微藻光合碳同化质能传递与转化机理

Microalgae have recently received growing attention given its prospects as a source of renewable energy and its potential for CO2 capture. Since microalgae are photosynthetic organisms, light, particularly light spectrum has key effect on carbon fixation rate. Due to the lack of knowledge about the different light demand between carbon fixation and lipids accumulation and the adjusting effect of light on carbon flow , the effect of light spectrum regulation was limited. Both energy transfer and oriented carbon transfer were hindered. Based on responding mechanism of photosynthetic energy capture and carbon assimilation to different light spectrum, this project proposes effective strategy to enhance photosynthesis and carbon fixation. Microalgal selective absorption of different light spectrum, energy absorption and conversion in photosynthetic pigments, electron transfer and energy utilization in photosynthetic reaction center, and energy metabolism will be studied. Figure out CO2 transfer and absorption among multiphase and mass transfer across membrane based on the stress reaction of cell wall to high CO2. Monitor accumulation dynamics of the cellular energy stores to demonstrate space-time dynamics and carbon metabolic competitive network with different light spectrum. Reveal the response mechanism of energy flow and organic carbon distribution to light spectrum regulation, and lead energy and mass to the biosynthesis of lipids. Optimize light field and flow field, enhance energy and mass transfer in photo-bioreactors to increase carbon fixation.

微藻捕集燃煤烟气CO2制备生物燃料，实现碳减排和碳循环，对国家应对气候变化和保障能源安全有积极作用。光是微藻固碳唯一能量来源，直接决定微藻生长固碳速率。微藻固碳、产油对光谱需求的多样性和光谱对碳代谢流的引导性缺乏研究，光谱调控针对性差，导致光合作用和碳同化途径的质能转化效率低。项目通过探究微藻光谱吸收特性、光合色素的能量传递转化过程、光合反应中心电子传递和能量分配机制、细胞能量代谢状态，揭示微藻固碳产油对光谱的需求规律，提高光合作用效率。通过细胞壁的应激反应分析高浓度CO2在多相界面上的吸附传递和分子跨膜传质过程，借助细胞成像等研究光谱调控对储能物质积累动力学特性的影响，构建储能物质代谢竞争网络和时空动态完整概念架构，探究微藻碳同化途径中的质能流转，揭示光谱调控引导能流方向和有机碳分配的微观机制，促进油脂合成。优化微藻固碳光合反应器的光场和流场，强化反应器内部传能传质，提高微藻固碳效率。

本项目多层次多角度分析了光谱调控和高碳胁迫交互作用下高效固碳微藻的能量吸收传递和碳同化质能转化过程规律，通过优化光能和碳源调控，提高了微藻固碳效率。通过高碳驯化后的微藻可在15%CO2快速生长，固碳速率可达2.57g/L/d。通过调控碳源和光质条件，固碳效率可进一步提高。当15%CO2与甲醇混合作为微藻碳源时，微藻固碳效率比仅用15%CO2时提高78.3%。光质调控和高碳胁迫协同作用结果显示，红蓝光比为2:1时，雨生红球藻的生物量和光合色素含量最高，分别较红光下高19%和62%。随着生长时间的推移，雨生红球藻对红、蓝光的需求均呈上升趋势，但蓝光的吸收增幅更为显著。在分别以红光和蓝光为主的红蓝光作用下，对比微藻代谢动态过程发现，在生长前期，红光更有利于促进糖酵解，TCA循环、氧化磷酸化等多条代谢通路，从而刺激细胞内的质量流动和能量传递；红光下细胞氨基酸的代谢显著较蓝光活跃，但淀粉和油脂等储能物质的代谢在蓝光下略高，并且，蓝光下雨生红球藻在清除ROS等外源性物质的应激性上表现略优于红光。在生长后期，蓝光下微藻捕光复合物表达上调说明蓝光强度不足，因此光合作用效率降低，淀粉和油脂等储能物质代谢较红光下调。在整个生长过程中，红光下的雨生红球藻质能传递过程均较蓝光活跃，但蓝光下细胞较同时期红光下细胞更成熟，具有较高的次级代谢水平和抗损伤能力。红光下，雨生红球生长前期的光合作用、能量传递和转录水平均高于后期，但在蓝光下则与之相反，说明在雨生红球藻生长前期红光是有利于生长固碳的，施加过多的蓝光则会抑制生长，相反，在生长后期，蓝光则更有利于生物质积累提高固碳效率。.利用高光谱成像和拉曼光谱显微镜成像技术，分别在宏观尺度和细胞尺度上建立了微藻储能物质积累动力学模型，其中，虾青素含量预测值与实际值的拟合度达85%。.设计研发了利用温差发电的双管式雨生红球藻培养系统，不仅依据微藻不同生长阶段的光需求特性，实现了光能的梯级利用，而且对藻液余热回收产能，用于微藻培养补光。