基于宏基因组学的草原土壤微生物对增温响应的研究

发布时间：2018-05-29 20:34

  本文选题：土壤微生物群落 + 草地　； 参考：《清华大学》2016年博士论文

【摘要】：草原生态系统作为陆地生态系统的最重要类型之一,承担着多种生态功能。土壤微生物作为分解者,在维持生态系统平衡上起着至关重要的作用。随着全球气候逐渐变暖,温度变化对土壤微生物群落的影响无疑也会影响到微生物驱动的生物地球化学循环。然而由于土壤微生物的复杂性,以及研究方法的限制,目前我们对于土壤微生物如何响应气候变暖的了解还非常有限。本研究以中国青藏高寒草原、中国内蒙古半干旱草原及美国加州半干旱草原为研究对象,利用宏基因组学技术中的高通量测序技术和基因芯片(GeoChip)技术,从土壤微生物群落的物种组成和功能结构角度深入探究微生物对增温的响应机制,本研究发现:(1)对三个草原生态系统增温试验的土壤微生物群落结构分析表明功能基因对增温响应比物种敏感。(2)土壤微生物群落物种组成在不同的增温条件下对增温有不同的响应策略。在内蒙古半干旱草原中(1℃,6年),微生物物种组成没有明显的变化。而在美国加州半干旱草原中(1—1.5℃,14年),生长快的富营养菌,如拟杆菌(Bacteroides)物种丰度降低,生长慢的寡营养菌,如酸杆菌(Acidobacteria)物种丰度升高。(3)土壤微生物功能基因在不同的增温条件下对增温有不同响应策略。在高寒草原中,碳固定基因丰度,氨化和反硝化基因丰度都在增温后降低,硝化基因丰度在增温后升高。且N2O排放量与硝化基因amoA丰度显著正相关,与反硝化基因nirS和norZ成负相关,该生态系统硝化作用是N2O排放的主导过程。在内蒙古半干旱草原中,光能固碳途径3HP和卡尔文循环基因丰度,氨化及反硝化基因丰度在白天增温下升高,夜间增温和全天增温下功能基因丰度没有显著变化。而在美国加州半干旱草原中,厌氧碳固定途径基因丰度在增温下升高,碳降解中易降解碳基因丰度升高而难降解碳基因丰度降低。此外,反硝化基因丰度降低。(4)功能基因和物种对增温响应不同原因是两者受不同环境因子影响。微生物物种组成主要受植被等因子影响,而功能基因结构主要受土壤营养影响。本研究全面分析了草原生态系统土壤微生物物种组成和功能结构对增温的响应,对于有效管理生态系统,减少未来气候变化所带来的不利影响有重要意义。
[Abstract]:Grassland ecosystem, as one of the most important types of terrestrial ecosystem, bears a variety of ecological functions. Soil microorganisms, as decomposers, play a vital role in maintaining ecosystem balance. With the global climate warming, the effect of temperature on soil microbial community will undoubtedly affect the biogeochemical cycle driven by microbes. However, due to the complexity of soil microbes and the limitations of research methods, our understanding of how soil microbes respond to global warming is very limited. In this study, the semi-arid steppe of Qinghai-Tibet, Inner Mongolia and California were used as the research objects, and the high-throughput sequencing technique and the gene chip GeoChip technique were used in macrogenomics. From the point of view of species composition and functional structure of soil microbial community, the response mechanism of microorganism to temperature was studied. In this study, we found that the soil microbial community structure of three steppe ecosystem temperature-increasing experiments showed that the functional genes were more sensitive to the temperature response than the species. 2) the species composition of the soil microbial community was increased under different temperature conditions. Temperature has different response strategies. In Inner Mongolia semi-arid steppe, there was no obvious change in microbial species composition at 1 鈩，

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