中国典型海岸带海域的微生物梯度分布现象研究

	中国典型海岸带海域的微生物梯度分布现象研究
	于淑贤1,2
学位类型	博士
导师	秦松
	2017-12
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	海洋生物学
关键词	海岸带微生物空间分布环境因素地理限制
摘要	海岸带是生物地球化学过程的重要区域，具有较高的生物多样性和生物生产力，并受到来自海洋和陆地的双重影响。由陆地和海洋主导的动态过程在海岸带造就了区域异质性的生态环境，也形成了多重的生物地球化学环境梯度。在众多因素影响下，微生物群落往往表现出空间分布差异。通过分析微生物群落的优势种群和多样性，以及环境因素、地理距离和深度在产生微生物生物地理分布中的相对贡献，有助于揭示微生物在海岸带环境下的维持多样性的机理。本文应用DNA标记基因的克隆测序、高通量测序等分子生物学方法，对典型海岸带水域中微生物的空间分布和多样性进行了探索性研究。采用ITS1作为DNA标记评估我国沿海表层水中的真核浮游生物多样性。BLAST结果表明，大部分ITS1序列隶属于6个真核类群，包括浮游动物、真菌和囊泡虫类等。这些主要的真核生物类群可以将采样点分为显著不同的5个聚类，而每个聚类中的特征真核生物门类表现出显著的地理分布差异。总体上，真核浮游生物群落的多样性水平与经度、纬度、水深、温盐等参数显著相关，自北向南有显著升高的趋势；而真核生物群落差异（β-多样性）随地理距离的增加而加大。这表明真核浮游生物在我国沿海表层水中显示出了地理限制。其中，真核微生物（真菌、甲藻等）可能与其它真核浮游生物具有相似的空间分布模式。因而本文提出海岸带微生物在海岸带环境下可能具有分布限制。为了研究南海北部表层水中的光合浮游植物群落，采用rbcL作为标记基因构建了33个克隆文库。BLAST结果显示，研究区域主要以不等鞭毛类和定鞭藻门为浮游植物的优势类群，而仅5个有害甲藻物种被检测到。根据α-多样性估计结果，N709的浮游植物群落具有较低的多样性和丰富度，这可能与其处于淡水与海水交汇的咸水环境中有关。依据β-多样性可以将所有的样本聚为3个类别，其中靠近海岸的较浅位点倾向于聚为一类。各位点的α-多样性指数与温度、深度和纬度具有显著的正相关或负相关关系。相关性检验结果表明，浮游植物群落的分布差异主要由温度决定，而地理距离等因素的影响并不显著。通过细菌16S rDNA高通量测序的方法，对南海北部水层及沉积表层细菌群落多样性及空间分布进行了比较分析，并检验了环境因素、地理限制及深度对微生物群落的影响。结果表明，约95%的细菌16S rDNA序列归属于γ-变形菌纲、厚壁菌门、蓝细菌门、α-变形菌纲等优势类群。沉积样本中的优势细菌类群主要与粒度、氮含量等环境参数相关，而水体样本的优势细菌类群与取样深度密切相关。相关性检验结果显示，沉积样本的α-多样性指数与碳含量有着显著的相关关系，而水体样本的α-多样性指数和β-多样性矩阵则显示与取样深度的显著相关。地理距离和海底深度对β-多样性的影响并不显著。通过高通量测序调查了细菌群落沿渤海至黄海北部梯度的分布。结果表明，细菌群落在海岸梯度下呈现出显著的水平和垂直方向的分布。α-变形菌纲、γ-变形菌纲、拟杆菌门、蓝细菌门等14个浮游细菌优势类群将样本分成3个类别，分别反映了沿海浅水（深度≤ 20 m）、表层水和底层水（沉积物以上2~3 m）的典型生境。每个类别中的判别性类群与空间和环境变量密切相关。环境因素（特别是浊度和亚硝酸盐）对表层细菌多样性有显著影响，而底层水体的群落相似性主要取决于深度。地理距离增加了细菌群落的差异性，并且在表层和底层水中限制了细菌的分布。细菌的扩散也受到磷酸盐的影响，这可能是由于在这个沿海海域的无机氮磷比较高。莱州湾以水产养殖而闻名，但多年来一直受到富营养化和污染的困扰。而小清河排放高浓度营养盐被认为是莱州湾西部富营养化的主要原因。通过高通量测序研究了微生物沿河流至海洋的空间梯度的分布。结果显示，细菌的优势类群包括γ-变形菌纲、拟杆菌门、δ-变形菌纲等，而真菌优势类群则是担子菌门、子囊菌门、壶菌门等。这些主要的细菌和真菌类群将样本聚成了2个截然不同的类别，而各类别中的判别性微生物与空间因素、环境因素有着显著的相关性。大部分的细菌和真菌优势组成均受到无机氮的调节。细菌群落的空间分布差异主要与磷酸盐的分布有关，这提示着细菌分布的磷酸盐限制模式。真菌群落的α-和β-多样性与水深呈显著的相关性。细菌和真菌群落依不同的梯度分布而呈现出不同的地理分布格局，这可能与微生物在生态系统中的生态功能有关。
其他摘要	Coastal zone is an important area of biogeochemical process with high biodiversity and biological productivity, and subject to the effects from ocean and land. The dynamic processes dominated by land and sea have created a heterogeneous ecological environment in the coastal zone and also formed multiple biogeochemical environmental gradients. Under these influences, microbial communities always present spatial distribution variation. Analyzing the dominant population and diversity of microbial communities, as well as the relative contribution of environmental factors, geographical distance and depth to microbial biogeography, are important for revealing the mechanism of microbes maintaining biodiversity in the coastal environment. Here we adopted molecular approaches, such as clone libraries and high-throughput sequencing, to explore the spatial distribution and biodiversity of microorganisms in typical coastal waters. In this study, ITS1 was used as a DNA marker to assess the biodiversity of eukaryotic plankton in surface waters of Chinese coastal seas. The results of BLAST showed that most ITS1 sequences belonged to six eukaryotic groups, including Metazoa, Fungi and Alveolata. These abundant eukaryotic taxa divided all samples into five distinct clusters, while discriminant taxa in each cluster showed significant spatial distribution variation. In general, α-diversity of eukaryotic community was significantly related to latitude, longitude, water depth, temperature and salinity, presenting an increase trend from north to south. Eukaryotic community dissimilarity (β-diversity) increased with the increasing geographical distance, which indicated a geographical limitation for eukaryotic plankton in Chinese coastal seas. Among the abundant taxa, eukaryotic microorganisms (fungi, dinoflagellates, etc.) may have similar spatial distribution patterns with the other eukaryotic plankton. We therefore propose that coastal zone microbes may have distributional constraints in the coastal zone. In order to study photosynthetic phytoplankton community in the surface waters of northern South China Sea, we constructed 33 clones using rbcL as a marker gene. The results of BLAST showed that the study area was mainly dominanted by Stramenopiles and Haptophyta, while only five harmful dinoflagellates species were observed. According to α-diversity estimators, community of N709 had very low genetic diversity and richness, which could be explained by the influence of brackish estuarine environment. β-diversity showed all samples could be grouped into three clusters and those samples with approximately the same distance to land clustered together. α-diversity of each sample had significant positive or negative correlation with temperature, depth and latitude. The results of correlation tests showed that distribution of phytoplankton community was mainly determined by temperature, while the influences from geographical distance and other factors were not significant. Through high-throughput sequencing of bacterial 16S rDNA, we compared and analyzed the diversity and spatial distribution of bacterial communities in water and sediments of northern South China Sea, as well as the effects from environment, depth and geographic distance. The results showed that about 95% of bacterial 16S rDNA sequences belonged to abundant taxa, including Gamma-proteobacteria, Firmicutes, Cyanobacteria, and Alpha-proteobacteria. The dominant bacteria in sediments were mainly related to environmental parameters such as grain size and nitrogen content, while the dominant bacteria in water were related to sampling depth. Correlation tests showed that α-diversity and carbon content in sediments had a significant correlation. Both α- and β-diversity of bacteria in water were significantly associated with sampling depth. However, we did not found bacterial β-diversity was significantly affected by geographic distance and seafloor depth. We performed high-throughput sequencing to investigate spatial distribution of bacterial communities along the gradients from Bohai Sea to northern Yellow Sea. The results showed bacterial communities presented remarkable horizontal and vertical distribution under coastal gradients. Fourteen abundant taxa, including Alpha-proteobacteria, Gamma-proteobacteria, Bacteroidetes and Cyanobacteria, clustered the samples into three distinctive groups, reflecting typical habitats in shallow coastal water (depth ≤ 20 m), sunlit surface layer and bottom water (at 2~3 m above sediment). Discriminant taxa of each cluster were strongly correlated to spatial and environmental variables. Environmental factors (especially turbidity and nitrite) exhibited significant influences on bacterial β-diversity in surface water, while community similarity in bottom water was mainly determined by depth. Geographic distance enhanced bacterial community dissimilarity and limited bacteria distribution in both surface and bottom water. Bacterial dispersal was also affected by phosphate, which was possible due to the high ratios of N/P in this coastal sea area. The Laizhou Bay is famous for aquaculture, but has been subject to eutrophication and contamination for years. High concentrations of nutrients from the Xiaoqing River are considered as the main cause for significant eutrophication in the west of Laizhou Bay. Here we present results of the research on sedimentary microbial assemblages along this spatial gradient between riverine and marine environments by high-throughput sequencing. Our results showed that the dominant bacteria included γ-Proteobacteria, Bacteroidetes, δ-Proteobacteria, while the dominant fungal taxa were related to Basidiomycotina, Ascomycota and Chytridiomycota. The predominant phyla/classes of bacteria and fungi clustered the samples into two distinct provinces, while discriminant taxa of each province were strongly associated with spatial factors and environmental factors. Dominant components of bacteria and fungi were regulated by inorganic nitrogen. Spatial variation of bacterial communities was mainly related with the distribution of phosphates, suggesting a phosphate-limitation pattern for the bacterial communities. α- and β-diversity of fungal communities exhibited a significant correlation with water depth. We consider the distinct distributional gradients of bacterial and fungal communities might be due to their functions in the coastal ecosystem.
语种	中文
文献类型	学位论文
条目标识符	http://ir.yic.ac.cn/handle/133337/23476
专题	中国科学院烟台海岸带研究所知识产出_学位论文
作者单位	1.中国科学院烟台海岸带研究所 2.中国科学院大学
第一作者单位	中国科学院烟台海岸带研究所
推荐引用方式 GB/T 7714	于淑贤. 中国典型海岸带海域的微生物梯度分布现象研究[D]. 北京. 中国科学院大学,2017.

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