磷元素对氮缺乏刺激小球藻产油率提高的调控机制及其在废水体系中的应用研究

It is well known that nitrogen starvation is an effective way to stimulate oil content in algal cells. However, the approach of nitrogen starvation raises a lot of controversial argument as it also reduces biomass productivity and lipid productivity. The applicant recently found that phosphorus played an important role in enhancing biodiesel productivity of Chlorella vulgaris under nitrogen deficiency, phosphorus was largely assimilated and formed polyphosphate in algal cells. In this project, firstly we aim to clarify the mechanism between phosphorus and lipids synthesis under nitrogen stress via the approaches of element assimilation, microalgae growth dynamics, physiology and biochemistry, polyphosphate formation and utilization, photosynthesis. Then Real-time PCR and proteomics are also adopted for deep study of molecular mechanism. Secondly, other important elements such as iron, magnesium and sulfur are investigated to find out whether the similar mechanism between these elements and lipid synthesis is existed, and the content of those elements will also be optimized. Finally, the above findings will be further verified in photo-bioreactor and synthetic wastewater. Meanwhile the system will be optimized and the cultivation feasibility of Chlorella vulgaris will be investigated too. It is expected that the research outcomes will provide new insight and technology for combing microalgal oil production and wastewater treatment.

利用氮缺乏刺激微藻油脂含量的提高已获得广泛认可，然而因氮限制导致的生物量产率降低而影响产油率的提高一直让该刺激方式备受争议。申请者的前期研究初步证实：磷的充足供应能显著提高绿藻的产油率，磷的吸收速率大幅提高的同时细胞内积累了大量的聚磷。申请者拟针对上述问题，在已有的研究基础上，采用典型能源微藻（小球藻）为研究对象，试图从元素吸收、微藻生长、微藻生理生化、聚磷的形成与分解利用、光合作用等代谢角度揭示磷元素和油脂高效合成的相互作用规律，同时利用Real time-PCR及蛋白组学等手段进一步阐明其中的分子作用机制；考察体系中重要元素铁、镁、硫在油脂产率提高过程中的作用规律，并优化培养体系中这些元素的含量；在模拟人工缺氮废水体系中验证上述研究结果，优化控制反应器的同时对该废水体系培养小球藻的可行性进行评估。本项目的实施能够为微藻高效产油和废水处理的耦合提供新的技术和理论依据。

以探明磷的充足供应显著提高绿藻产油率的作用机理为目的，本研究采用典型能源微藻（普通淡水小球藻）为研究对象，从磷元素吸收、微藻生长、微藻生理生化、聚磷的形成、光合作用等代谢角度揭示了磷元素和油脂高效合成的相互作用规律，同时利用转录组学从多种不同代谢路径进一步阐明了其中的分子作用机制。而后，在15%CO2浓度条件下，利用了两阶段培养方法验证了蛋白核小球藻的在充足磷的供应下协同提高生物量和油脂产率的可行性，通过胞内磷形态的定性和定量分析，揭示各种不同形态磷之间的转化关系，通过蛋白组学对相关蛋白表达量的定量分析，阐明了光合作用和氧化磷酸化路径中ATP合成酶表达量的提高以及碳固定和甘油三酯代谢路径的相关酶表达量的提高对于微藻生物量和油产率提高的促进作用。通过添加低浓度的亚腈胺提高微藻对高浓度CO2和光照强度的耐受性，从而提高小球藻的生长速率。通过设计并优化切圆旋流柱式反应器以增加藻液流速，强化闪光效应，提高传质系数从而增加微藻的光合作用效率和生长速率。