昆仑山垭口深层多年冻土微生物多样性及构建机制研究
发布时间：2018-11-17 19:53
【摘要】：多年冻土(permafrost)是地球上陆地冰冻圈的重要组成部分并且代表了一个关键的有机碳库。微生物,包括细菌、古菌、光养性的蓝细菌和绿藻、真菌以及原生动物,构成了多年冻土中主要的生物量与物种多样性,并影响着多个重要的生物地球化学过程。近几十年来,全球气候变暖对多年冻土环境的影响备受关注,多年冻土融化以及微生物降解土壤有机质所导致的温室气体(二氧化碳、甲烷和一氧化二氮)释放被认为是陆地生态系统向全球大气系统反馈的主要途径之一。确定冻土微生物群落的组成并理解它们的功能角色以及其如何响应气候变化和多年冻土融化,是生态学家当前关注的热点问题。青藏高原是独特而脆弱的生态系统,该地区分布的低纬度、高海拔多年冻土对于气候变化尤为敏感。然而,与两极地区相比,青藏高原冻土微生物研究相对薄弱,难以为世界上其他地区开展的冻土微生物研究以及该地区其他学科的研究提供科学依据和数据参考。本文以取自青藏高原腹地昆仑山垭口盆地的冻土样品为材料,研究了冻土微生物(细菌、古菌和真菌)的生理生化特性、多样性与群落结构,探讨了冻土微生物群落的空间分布格局及生态驱动机制。主要结果摘要如下:(1)青藏高原昆仑山垭口多年冻土中微生物总数介于108~109个/克之间,可培养细菌数量为103~106 CFU/克土壤(干重);系统发育分析表明可培养细菌多样性很高且隶属于放线菌门(Actinobacteria)、厚壁菌门(Firmicutes)、变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和异常球菌-栖热菌门(Deinococcus-Thermus)5个类群的44个属,其中优势属为节杆菌属(Arthrobacter)、嗜冷杆菌属(Psychrobacter)、动性球菌属(Planococcus)、芽孢杆菌属(Bacillus)及细杆菌属(Microbacterium);生理生化特性研究表明分离的细菌菌株大多为耐冷菌,少数则具有嗜冷和嗜温特征,并且93.6%和49.0%的菌株分别具有耐碱和耐盐能力。可培养真菌数量很低,介于0~103 CFU/克土壤(干重)之间,其隶属于子囊菌门(Ascomycota)和担子菌门(Basidiomycota)的5个属:地丝霉属(Geomyces)、枝孢霉属(Cladosporium)、链格孢属(Alternaria)、红酵母属(Rhodotorula)与隐球酵母属(Cryptococcus)。(2)从青藏高原昆仑山垭口冻土中共发现62个真菌分子种,包括25个新种;真菌群落隶属于子囊菌门、担子菌门和毛霉亚门(Mucoromycotina)3个类群的10个纲,其中座囊菌纲(Dothideomycetes)的多样性和相对丰度均最高;一些真菌类群广泛存在于世界各地的多年冻土环境中,可能代表了世界广布的嗜冷或耐冷真菌;真菌群落组成随着深度变化,且在活动层和永冻层间差异显著,土壤电导率是影响真菌群落组成的重要因子。(3)在青藏高原昆仑山垭口冻土岩芯中,共检测出191个细菌分子种,隶属于14门、52目,其中包括19个新目和108个新种,且变形菌门为优势类群;细菌群落的α多样性随深度增加而降低,且活动层样品中多样性高于永冻层;细菌群落同样随深度变化,且相对于永冻层,活动层样品中群落组成差异更大;多种测量的土壤理化因子影响了细菌群落组成,其中土壤碳氮比和有机碳含量的影响尤为显著。(4)相比于细菌,古菌群落的多样性很低,共检测到17个分子种,隶属于奇古菌门(Thaumarchaeota)与广古菌门(Euryarchaeota)的3个纲:Group I.1a、Group I.1b和热原体纲(Thermoplasmata),其中包括1个新目和13个新种;高达99%的古菌克隆与三个已知的氨氧化古菌(Ammonia-oxidizing archaea,AOA)Candidatus Nitrosoarchaeum limnia、Candidatus Nitrososphaera gargensis和Nitrososphaera viennensis亲缘关系密切;该结果暗示了氨氧化古菌在该地区多年冻土生态系统的碳氮循环过程中扮演着关键角色。(5)为了阐明细菌群落垂直分布的驱动机制,本文从生态和进化的角度进一步分析了细菌群落的空间变化及谱系格局。物种和谱系beta多样性分析显示,沿着冻土岩芯剖面,细菌群落并不是随机的分布,而是显示了距离衰减的分布格局;在5个采样深度中,细菌群落的谱系结构是随机的,然而所有群落显示了平均的趋势朝着谱系聚集;这些结果表明驱动细菌群落垂直分布的生态学过程主要是确定性的生态选择,然而随机性过程同样发挥着作用。
[Abstract]:Permafrost is an important part of the earth's land freeze and represents a key organic carbon reservoir. The microorganisms, including bacteria, archaea, phototrophic cyanobacteria and green algae, fungi and protozoa, constitute the main biomass and species diversity in the permafrost, and affect many important biogeochemical processes. In recent decades, the effects of global warming on the permafrost environment have been of great concern, and the permafrost and the greenhouse gases (carbon dioxide, The release of methane and nitrous oxide) is considered one of the main ways to feed the terrestrial ecosystem to the global atmospheric system. It is a hot issue for ecologists to determine the composition of the frozen soil microbial community and understand their functional roles and how they respond to climate change and permafrost. The Qinghai-Tibet Plateau is a unique and fragile ecosystem. The low-latitude and high-altitude permafrost in the region is particularly sensitive to climate change. However, compared with the two-pole region, the research on the micro-organism of the frozen soil in the Qinghai-Tibet Plateau is relatively weak, and it is difficult to provide scientific basis and data reference for the research of the frozen soil microorganisms in other parts of the world and the research of other disciplines in the region. In this paper, the physiological and biochemical characteristics, diversity and community structure of the frozen soil microorganisms (bacteria, archaea and fungi) were studied, and the spatial distribution pattern and the ecological driving mechanism of the frozen soil microbial community were discussed. The main results are as follows: (1) The total number of microorganisms in the permafrost of the Kunlun Mountains in the Qinghai-Tibet Plateau is between 108 and 109/ g, and the number of bacteria can be 103-106 CFU/ g of soil (dry weight); the phylogenetic analysis shows that the bacterial diversity is high and belongs to the actinomycete. A total of 44 genera of 5 taxa of the 5 groups of the genus Firmicin, Proteobacteria, Bacteroides, and Deinococcus-Therus, the dominant species are Arthrobacter, Psychrobacter, and Planococcus, The results of the physiological and biochemical characteristics of Bacillus and Microbacterium showed that the isolated bacterial strains were mostly cold resistant bacteria, and a few were cold and warm, and 93.6% and 49. 0% of the strains had the ability of alkali and salt tolerance, respectively. The number of cultivable fungi is very low, between 0 and 103 CFU/ g of soil (dry weight), belonging to 5 genera of Ascomyota and Baidota, which belong to the genus Geotrichum, Cladosporium, Alternaria, Rhodotorula and Cryptococcus. (2) 62 fungal species, including 25 new species, were found in the frozen soil of the Kunlun Mountains in the Qinghai-Tibet Plateau, including 25 new species, and the fungal community was attached to 10 classes of 3 groups of the Ascomycetes, Basidiomycetes and Mucor, with the highest diversity and relative abundance; Some of the fungus groups are widely present in the permafrost environment around the world, which may represent the cold or cold-resistant fungi in the world. The composition of the fungus community varies with the depth, and the difference between the active layer and the permanent freezing layer is significant, and the soil conductivity is an important factor affecting the composition of the fungus community. (3) A total of 191 species of bacterial species, including 19 new species and 108 new species, were detected in the frozen soil core of the Kunlun Mountain in the Qinghai-Tibet Plateau, and there were 19 new species and 108 new species. The diversity of the bacterial community decreased with the increase of the depth. in that active lay sample, the diversity is higher than that of the permanent freezing layer; the bacterial community also changes with the depth, and the composition difference of the community in the sample of the active layer is greater with respect to the permanent freezing layer; and the soil physical and chemical factors of the various measurement influence the composition of the bacterial community, in which the effect of the carbon-to-nitrogen ratio and the organic carbon content of the soil is particularly significant. (4) As compared with the bacteria, the diversity of the archaea community was very low, and 17 species were detected, belonging to three classes: Group I. 1a, Group I. 1b and Thermoplasmatata, which included 1 new and 13 new species. The results suggested that the ammonia-oxidizing archaea plays a key role in the process of the carbon-nitrogen circulation in the permafrost ecosystem in the region. (5) In order to clarify the driving mechanism of the vertical distribution of the bacterial community, the spatial and genealogical pattern of the bacterial community was further analyzed from the angle of ecology and evolution. The diversity analysis of species and genealogy shows that the bacterial community is not a random distribution along the core section of the frozen soil, but the distribution pattern of the distance attenuation is shown; in 5 sampling depths, the spectral structure of the bacterial community is random, However, all communities show that the average trend is toward the lineage; these results indicate that the ecological process of driving the vertical distribution of the bacterial community is mainly the deterministic ecological choice, but the random process also plays an important role.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q938
，
本文编号：2338877
[Abstract]:Permafrost is an important part of the earth's land freeze and represents a key organic carbon reservoir. The microorganisms, including bacteria, archaea, phototrophic cyanobacteria and green algae, fungi and protozoa, constitute the main biomass and species diversity in the permafrost, and affect many important biogeochemical processes. In recent decades, the effects of global warming on the permafrost environment have been of great concern, and the permafrost and the greenhouse gases (carbon dioxide, The release of methane and nitrous oxide) is considered one of the main ways to feed the terrestrial ecosystem to the global atmospheric system. It is a hot issue for ecologists to determine the composition of the frozen soil microbial community and understand their functional roles and how they respond to climate change and permafrost. The Qinghai-Tibet Plateau is a unique and fragile ecosystem. The low-latitude and high-altitude permafrost in the region is particularly sensitive to climate change. However, compared with the two-pole region, the research on the micro-organism of the frozen soil in the Qinghai-Tibet Plateau is relatively weak, and it is difficult to provide scientific basis and data reference for the research of the frozen soil microorganisms in other parts of the world and the research of other disciplines in the region. In this paper, the physiological and biochemical characteristics, diversity and community structure of the frozen soil microorganisms (bacteria, archaea and fungi) were studied, and the spatial distribution pattern and the ecological driving mechanism of the frozen soil microbial community were discussed. The main results are as follows: (1) The total number of microorganisms in the permafrost of the Kunlun Mountains in the Qinghai-Tibet Plateau is between 108 and 109/ g, and the number of bacteria can be 103-106 CFU/ g of soil (dry weight); the phylogenetic analysis shows that the bacterial diversity is high and belongs to the actinomycete. A total of 44 genera of 5 taxa of the 5 groups of the genus Firmicin, Proteobacteria, Bacteroides, and Deinococcus-Therus, the dominant species are Arthrobacter, Psychrobacter, and Planococcus, The results of the physiological and biochemical characteristics of Bacillus and Microbacterium showed that the isolated bacterial strains were mostly cold resistant bacteria, and a few were cold and warm, and 93.6% and 49. 0% of the strains had the ability of alkali and salt tolerance, respectively. The number of cultivable fungi is very low, between 0 and 103 CFU/ g of soil (dry weight), belonging to 5 genera of Ascomyota and Baidota, which belong to the genus Geotrichum, Cladosporium, Alternaria, Rhodotorula and Cryptococcus. (2) 62 fungal species, including 25 new species, were found in the frozen soil of the Kunlun Mountains in the Qinghai-Tibet Plateau, including 25 new species, and the fungal community was attached to 10 classes of 3 groups of the Ascomycetes, Basidiomycetes and Mucor, with the highest diversity and relative abundance; Some of the fungus groups are widely present in the permafrost environment around the world, which may represent the cold or cold-resistant fungi in the world. The composition of the fungus community varies with the depth, and the difference between the active layer and the permanent freezing layer is significant, and the soil conductivity is an important factor affecting the composition of the fungus community. (3) A total of 191 species of bacterial species, including 19 new species and 108 new species, were detected in the frozen soil core of the Kunlun Mountain in the Qinghai-Tibet Plateau, and there were 19 new species and 108 new species. The diversity of the bacterial community decreased with the increase of the depth. in that active lay sample, the diversity is higher than that of the permanent freezing layer; the bacterial community also changes with the depth, and the composition difference of the community in the sample of the active layer is greater with respect to the permanent freezing layer; and the soil physical and chemical factors of the various measurement influence the composition of the bacterial community, in which the effect of the carbon-to-nitrogen ratio and the organic carbon content of the soil is particularly significant. (4) As compared with the bacteria, the diversity of the archaea community was very low, and 17 species were detected, belonging to three classes: Group I. 1a, Group I. 1b and Thermoplasmatata, which included 1 new and 13 new species. The results suggested that the ammonia-oxidizing archaea plays a key role in the process of the carbon-nitrogen circulation in the permafrost ecosystem in the region. (5) In order to clarify the driving mechanism of the vertical distribution of the bacterial community, the spatial and genealogical pattern of the bacterial community was further analyzed from the angle of ecology and evolution. The diversity analysis of species and genealogy shows that the bacterial community is not a random distribution along the core section of the frozen soil, but the distribution pattern of the distance attenuation is shown; in 5 sampling depths, the spectral structure of the bacterial community is random, However, all communities show that the average trend is toward the lineage; these results indicate that the ecological process of driving the vertical distribution of the bacterial community is mainly the deterministic ecological choice, but the random process also plays an important role.
【学位授予单位】：兰州大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：Q938
，
本文编号：2338877
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