表面活性剂胁迫对小球藻吸收氮磷的影响及分子机制

藻类广泛存在于水环境，其生物膜体系在城市污水脱氮除磷过程中具有良好运用前景。水处理中与氮磷共存表面活性剂等有机污染物，但目前关于表面活性剂胁迫对藻类吸收氮磷的影响缺乏深入认识。本项目以小球藻为代表，研究表面活性剂胁迫对藻类吸收氮磷的影响及分子机制。在了解其吸收不同形态氮磷动力学特征的基础上，考察表面活性剂胁迫下小球藻吸收氮磷的效率。通过测定细胞膜性状，细胞核、线粒体及叶绿体的形态，以及叶绿素含量和净光合作用速率，明确表面活性剂胁迫下氮磷吸收过程中藻细胞性状的变化。构建氮磷诱导小球藻抑制性差减文库，通过全文库测序进行表达序列标签的同源比对和功能分类，筛选出小球藻氮磷吸收的关键基因，并以此为靶基因采用Real-time PCR技术分析表面活性剂对其转录量的影响，从分子水平上深入阐明胁迫机制。研究成果可丰富水环境中藻类对氮磷的吸收理论，对指导藻类脱氮除磷的实际运用具有重要意义。

Algae is ubiquitous in aquatic environment, and algal biofilm system can be utilized in removal of nitrogen and phosphorus in municipal waste water treatment. Though surfactants usually coexist with nitrogen and phosphorus in water treatment, the effect of surfactants on the sorption of nitrogen and phosphorus is very limited. This proposal aims to investigate the effect and its molecular mechanism of surfactant stress on sorption of nitrogen and phosphorus with selecting Chlorella vulgaris (a single-celled green alga) as model. Based on the acquaintance of dynamic characteristics in sorption of nitrogen and phosphorus with different forms, the sorption rate will be investigated under the stress of surfactants with different kinds of charge. Meanwhile, the variation of algal cell (cell membrane and cell nucleolus, chondriosome and chloroplast, content of chlorophyll and net rate of photosynthesis) will be detected. Furthermore, the key genes of Chlorella vulgaris, which are related to metabolism of nitrogen and phosphorus, will be identified by sequencing and databases searching of isolated Expressed Sequence Tag (EST）from the constructed suppression subtractive cDNA library induced by nitrogen and phosphorus.The transcription differences of the key related genes in the sorption of nitrogen and phosphorus under the stress of surfactants will be analyzed, which can elucidate the stress mechanism at molecular level. The results are important to enhance the sorption theory of nitrogen and phosphorus by algae in environment, meanwhile are important to guide the application of algae in removal of nitrogen and phosphorus in water treatment.