乌勇布拉克盐湖嗜盐古菌多样性及其生理生态功能研究

Salt lakes, due to the presence of high concentration of salts are considered one of the extreme environments. These unique habitats have been occupied by diverse microbial population mainly halophilic archaea. Further study the diversity of halophilic archaea and their physiological ecological function in salt lake is of significance to know the forming and adaptive mechanism of microbial population and has important theoretical significance and application value to understanding of the biogeochemical cycle process in salt lake ecosystem. This project aims to study the diversity of halophilic archaea Wuyongbulake salt lake and investigate their physiological and ecological functions using cultivation-dependent and cultivation-independent methods. Different media and culture methods will be designed to establish a scientific and effective method for isolating previously uncultured halophilic archaea. Correlation between the different physicochemical parameters and geographical distribution of samples collected from various depths will be made with the archaeal community distribution to help us understand the composition of halophilic archaea in these environments. Successful implementation of physiological and biochemical properties, enzyme activity characteristics, polyhydroxyalkanoates and exopolysaccharides production, the role of N/P/S cycle and genomic information of representative strains, help us in understanding the community characteristics and control factors of halophilic archaea, exploring their ecological function in in wuyongbulake salt lake.

盐湖是一种极端高盐环境，蕴含丰富的微生物资源。嗜盐古菌作为盐湖微生物的重要组成部分，深入研究该类群的多样性及其生理生态功能对于理解盐湖生境中嗜盐古菌群落结构和适应机制以及在生物地球化学循环过程中所起的作用具有重要的理论意义和应用价值。本项目利用纯培养与免培养相结合的方法，参考采样地点理化参数，设计培养基及培养条件，开展对乌勇布拉克盐湖嗜盐古菌多样性研究，拟建立一套针对嗜盐古菌科学有效的分离方法，深入挖掘嗜盐古菌资源；结合对代表性菌株的生理生化性质、酶活特征、聚羟基脂肪酸酯及胞外多糖产生、N、P、S等循环作用及部分基因组信息的检测分析，共同揭示嗜盐古菌在乌勇布拉克盐湖中的群落特征及控制因素，探索该类群的生态功能。

嗜盐古菌具有特殊的进化地位同时含有丰富的酶及代谢产物，在盐湖生态中具有重要的作用。本研究以乌勇布拉克盐湖为研究对象，通过纯培养、高通量测序技术，构建嗜盐古菌纯培养分离方法，探究乌勇布拉克盐湖嗜盐古菌多样性；同时结合宏基因组及纯培养物基因组信息，探究嗜盐古菌的生态功能及代谢反应。高通量多样性分析表明乌勇布拉克盐湖盐湖中蕴含丰富的嗜盐古菌资源，在含盐较高的样点中嗜盐古菌为优势类群。18-20%NaCl条件富集，几丁质、甘露糖、甘露醇、海藻糖、鼠李糖、甘油富集，干热、紫外辐射处理能够增加稀有类群或潜在新物种的富集效果。采用恩诺沙星、诺氟沙星、制霉菌素、新霉素处理能够增加特殊嗜盐古菌类群，尤其是提高产丝嗜盐古菌的检出效果。基于高通量测序结论设计纯培养分离方法，共分离到近500株嗜盐古菌，分布于：Haloarcula、Haloterrigena、Halomicrobium、Halalkalicoccus、Halobiforma、Halobacterium、Halopiger、Halorubrum、Halosimplex、Halostella、Halovivax、Natrialba、Natrinema、Natronoarchaeum、Natronolimnobius、Saliphagus、Natronorubrum、Halopelagius、Halogeometricum、Haladaptatus、Natronomonas、Halostella、Halostagnicola、Halorusus、Halocatena 25个已知属及17个潜在新属分类单元；尤其是特殊形态的产丝嗜盐古菌类群被发现并且建立起有效的纯培养方法。从乌勇布拉克盐湖分离到的嗜盐古菌，在碳素、氮素、硫素、磷素的代谢中具有重要的功能，通过基因组的分析以及实验检测，验证了A869-1、A121-1、A267-1、A218等菌株具有特殊的芳香烃化合物降解、有机酸的生成及促进硫酸铵镁盐的形成功能，在高氮、高磷、高烃高盐废水处理中具有重要的应用前景。宏基因组的数据表明，乌勇布拉克盐湖蕴含丰富的古菌和细菌资源，拼接到大量的Nanohaloarchaeota和一些潜在的新门分类单元。本项目的实施，增强了对嗜盐古菌资源的挖掘、开发及利用，特殊的产丝嗜盐古菌的发现，对于进一步探究这一类群的形态演变规律及生态功能具有重要的意义。