草型湖泊附植生物膜藻类对反硝化菌群落及功能的影响机理

In macrophtic lakes, various kinds of substances, including algae, fungi, bacteria, and organic and inorganic detrital material etc., form epiphytic biofilms on surfaces of a wide variety of submerged macrophytes. These biofilms are hot spots of biogeochemical processes and have important influence on water environmental quality. Currently, the interactions between epiphytic-biofilm algae and bacteria, and the related metabolic processes are affteced by a number of factors, while it is still unclear what impact these algae will have on denitrifying bacteria communities. According to past studies, in the biofilms, the increment in the population of algae can speed the rate of denitrification and change the structure of denitrifying bacteria communities.Based on our studies, the synergistc relationship between epiphytic-biofilm algae and denitrifying bacteria epiphytic is related to the different secretion of algae. Thus, this project aims to study on typical submerged macrophytes, epiphytic biofilms and denitrifying bacteria communities, then find out what kinds of algae afftect denitrifying. The difference in the secretion of different algae will be distinguished by using fingerprint technology.The relationship between the secretion of algae and denitrifying bacteria communities ,and their functions will be studied by using simulation , and then the influence mechanism of epiphytic biofilms on denitrifying bacteria communities and denitrification will be researched. The achievement of this study will indicate the interaction of organisms in epiphytic biofilms, and it is important that submerged macrophytes will be used for ecological regulation and improving wate quality.

草型湖泊中沉水植物大面积分布，其表面常富集大量藻类、细菌、真菌、有机和无机碎屑，形成附植生物膜，是生物地球化学过程热区，对水环境质量具有重要影响。附植生物膜有机体间联系紧密，但藻类与反硝化菌群落及功能间的关系尚不清楚。据研究，生物膜中藻类数量最多的反硝化速率最大，反硝化菌群落结构也不同。我们认为，附植生物膜藻类与反硝化菌之间的这种协同关系与藻类种间分泌物不同有关。为此，本项目拟通过对草型湖泊中典型沉水植物附植生物膜藻类、反硝化菌群落及功能的研究，找出影响反硝化作用的藻类，并应用指纹图谱辨识藻类种间分泌物差异；在此基础上，通过模拟试验，研究藻类分泌物与反硝化菌群落及反硝化作用的关系，揭示藻类对反硝化菌群落及功能的影响机制。结果将增加附植生物膜有机体间互作关系的理解，对于正确认识和利用沉水植物的生态调控功能、改善水环境质量具有重要意义。

草型湖泊中沉水植物大面积分布，其表面常富集大量藻类、细菌、真菌、有机和无机碎屑，形成附植生物膜，是生物地球化学过程热区，对水环境质量具有重要影响。附植生物膜藻类与细菌的互作及其介导的生物地球化学过程受多种因素影响，但是藻类物种对反硝化菌群落及其功能的影响尚不清楚。本研究通过对贵州草海典型沉水植物附植生物膜为研究对象，通过野外定期采样，采用高通量测序、扫描电子显微镜等技术手段，研究了附植生物膜中藻类、细菌及反硝化功能菌群落组成及构建机制，阐明了藻类与细菌及反硝化功能菌之间生态网络关系。发表学术论文11篇，其中中国科学院SCI分区1-2区5篇；培养硕士研究生5名（毕业）。参加学术会议3次。.（1）揭示了附植生物膜的形貌、物质组成及藻类群落组成：附植生物膜成层状不均匀分布于茎叶表面，具有较高铁锰氧化物含量；附植共鉴定出6门，88种。其中绿藻门种类数最多，共有46种，占总数的52.27％；硅藻门共有22种，占25.00％；蓝藻门14种，占15.91％。藻类群落具有明显的季节变化，叶形复杂度对藻类组成影响显著。.（2）揭示了附植生物膜中细菌及反硝化功能菌群落组成与动态：附植生物膜中Gammaproteobacteria, Firmicutes, Alphaproteobacteria, Cyanobacteria， Bacteroidetes，and Actinobacteria常见主要类群。附生细菌群落丰富度(Chao1指数)和群落多样性都具有显著季节差异，11月群落丰富度和群落多样性显著高于7月(P<0.05)。温度与附生细菌群落结构相关性显著(R=0.35146,P<0.05)。附植生物膜中nirS型反硝化菌主要由未分类的细菌(unclassified bacteria) (55.81%)、变形杆菌(Proteobacteria) (34.11%)。.（3）揭示了附植生物膜中藻类、细菌、反硝化菌生态关系及群落构建机制：附植生物膜中藻类、细菌及反硝化功能菌群落生态网络共现模式以正相关为主，可能是藻类分泌碳源促进反硝化菌生长形成互惠关系；细菌、反硝化菌及藻菌网络关系随着生物膜的发育（季节）网络复杂性逐渐增强；附植生物膜中细菌、反硝化菌群落构建均以确定性过程主导。

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