乌梁素海湖滨湿地细菌与氨氧化细菌群落结构空间异质性成因分析

发布时间：2018-12-12 05:46

【摘要】：乌梁素海成为世界上沼泽化速度最快的湖泊之一,正向芦苇沼泽→碱蓬盐化草甸→白刺荒漠方向演化。本文探究了乌梁素海富营养化湖泊湿地演化过程中,水陆过渡带沉积物以及土壤中氨氧化细菌群落的组成、丰度、亲缘关系以及多样性变化,结合湿地理化囚子探讨基质条件对氨氧化细菌群落结构的影响；以及细菌群落的组成、丰度以及多样性变化,结合土壤理化因子探讨其对细菌群落结构的影响。本文采用湿地总DNA提取法提取沉积物和土壤总DNA,对氨氧化细菌群落的amoA基因构建克隆文库,并进行测序,分析湿地沉积物与土壤过渡带4个样点中氨氧化细菌群落结构的组成、丰度、亲缘关系以及多样性指标；分析基质条件变化对氨氧化细菌群落结构的影响；以及对细菌群落的16S rDNA基因进行高通量测序,分析各样品中细菌群落结构的组成、丰度以及多样性指标；土壤理化性质采用标准方法测定,分析其对细菌群落结构的影响。主要得到以下几方面的结论：第一、建立了具有自主知识产权的新的快速高效沉积物微生物总DNA提取方法。本文首次采用重铬酸钾溶液处理沉积物样品,结合机械裂解与化学试剂裂解相结合的手段,直接裂解微生物细胞将其溶解于DNA提取缓冲液进而获得高质量的微生物总DNA。第二、富营养化湖泊湿地水陆过渡带氨氧化细菌从与Nitrosomonas-like序列相似为主要优势类群向与Nitrosospira-like序列相似为主要优势类群转变,群落结构空间异质性成因主要由总氮和水溶盐总量这两个基质因子所主导。第三、沼泽化湿地及其过渡带土壤中细菌群落形成空间异质性的重要环境因子为总磷、水溶盐总量和铵态氮。第四、氮是富营养化湖泊形成的重要因子,本文提出关于富营养化湖泊沉积物过量氮元素去除的微生物学机制可能为：氨氧化细菌将铵态氮氧化为羟氨,进一步转化为亚硝态氮或硝态氮,这个过程耦合了硫化物的氧化过程,最终以氮气的形式将沉积物中的化合态氮化物转变为气态的氮气排放到大气中去以缓解含有大量氮元素的农田退水排入乌梁素海对其生态系统功能造成的影响。
[Abstract]:Wuliangsuhai is one of the most rapidly swamp lakes in the world, and it is evolving towards the desert of Suaeda salsa. In this paper, the composition, abundance, phylogenetic relationship and diversity of ammonia-oxidizing bacteria community in sediments and soils of eutrophic lake wetland in Wuliangsuhai were studied. The effects of substrate conditions on the community structure of ammonia-oxidizing bacteria were studied. The composition, abundance and diversity of bacterial community, and the effects of soil physical and chemical factors on the structure of bacterial community were discussed. In this paper, a clone library was constructed by extracting total DNA, from sediment and soil by extracting total DNA from sediments and soil to construct a clone library of Ammonia-oxidizing bacteria (Amox) community, and sequenced it. The composition, abundance, phylogenetic relationship and diversity index of ammonia-oxidizing bacteria community in four sites of wetland sediment and soil transition zone were analyzed. The effects of substrate conditions on the structure of ammonia-oxidizing bacteria community were analyzed, and the 16s rDNA gene of the bacterial community was analyzed by high-throughput sequencing to analyze the composition, abundance and diversity of bacterial community structure in each sample. The physical and chemical properties of soil were determined by standard method, and the effects of soil physical and chemical properties on bacterial community structure were analyzed. The main conclusions are as follows: first, a new rapid and efficient DNA extraction method for sediment microorganisms with independent intellectual property rights was established. In this paper, potassium dichromate solution was used to treat sediment samples for the first time. Combined with mechanical cracking and chemical reagent cracking, microorganism cells were directly dissolved in DNA buffer solution to obtain high quality total microbial DNA.. Secondly, the ammonia-oxidizing bacteria in eutrophication lake wetland transition zone changed from Nitrosomonas-like sequence similarity as main dominant group to Nitrosospira-like sequence similarity as main dominant group. The spatial heterogeneity of community structure was mainly caused by two matrix factors, total nitrogen and total dissolved salt. Third, the important environmental factors for the formation of spatial heterogeneity of bacterial communities in the swamp wetland and its transitional zone are total phosphorus, total dissolved salt and ammonium nitrogen. Fourthly, nitrogen is an important factor in the formation of eutrophication lakes. The microbiological mechanism of excess nitrogen removal in eutrophic lake sediments may be as follows: ammonia-oxidizing bacteria oxygenate ammonium to hydroxyl ammonia. Which is further converted to nitrite or nitrate nitrogen, a process coupled with the oxidation of sulfides, In the end, the combined nitrogen in sediments is transformed into gaseous nitrogen in the form of nitrogen to be discharged into the atmosphere in order to mitigate the effect on ecosystem function of farmland retreating water with a large amount of nitrogen elements into the Wuliangsu Sea.
【学位授予单位】：内蒙古大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：Q938

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