Bai Shijie, Zhang Jian, Qi Xiaoxue, Zeng Juntao, Wu Shijun, Peng Xiaotong
Institute of Deep-Sea Science and Engineering, Chinese Academy of Sciences, Sanya 572000, China.
The State Key Laboratory of Fluid Power & Mechatronic Systems, Zhejiang University, Hangzhou 310027, China.
Microorganisms. 2023 Feb 20;11(2):536. doi: 10.3390/microorganisms11020536.
The transition areas of riverine, estuarine, and marine environments are particularly valuable for the research of microbial ecology, biogeochemical processes, and other physical-chemical studies. Although a large number of microbial-related studies have been conducted within such systems, the vast majority of sampling have been conducted over a large span of time and distance, which may lead to separate batches of samples receiving interference from different factors, thus increasing or decreasing the variability between samples to some extent. In this study, a new in situ filtration system was used to collect membrane samples from six different sampling sites along the Sanya River, from upstream freshwater to the sea, over a nine-hour period. We used high-throughput sequencing of 16S and 18S rRNA genes to analyze the diversity and composition of prokaryotic and eukaryotic communities. The results showed that the structures of these communities varied according to the different sampling sites. The α-diversity of the prokaryotic and eukaryotic communities both decreased gradually along the downstream course. The structural composition of prokaryotic and eukaryotic communities changed continuously with the direction of river flow; for example, the relative abundances of and increased with distance downstream, while and decreased. Some prokaryotic taxa, such as and , were present nearly exclusively in pure freshwater environments, while some additional prokaryotic taxa, including the , , , and , were barely present in pure freshwater environments. The eukaryotic communities were mainly composed of the , , , , , and . The prokaryotic and eukaryotic communities were split into abundant, common, and rare communities for NCM analysis, respectively, and the results showed that assembly of the rare community assembly was more impacted by stochastic processes and less restricted by species dispersal than that of abundant and common microbial communities for both prokaryotes and eukaryotes. Overall, this study provides a valuable reference and new perspectives on microbial ecology during the transition from freshwater rivers to estuaries and the sea.
河流、河口和海洋环境的过渡区域对于微生物生态学、生物地球化学过程以及其他物理化学研究而言具有特别重要的价值。尽管在此类系统内已经开展了大量与微生物相关的研究，但绝大多数采样是在很长的时间跨度和空间距离上进行的，这可能导致不同批次的样本受到不同因素的干扰，从而在一定程度上增加或降低了样本之间的变异性。在本研究中，我们使用了一种新型原位过滤系统，在9小时内从三亚河上游淡水区域到入海口的六个不同采样点采集膜样本。我们运用16S和18S rRNA基因的高通量测序技术来分析原核生物和真核生物群落的多样性及组成。结果表明，这些群落的结构因采样点的不同而各异。原核生物和真核生物群落的α多样性均沿下游方向逐渐降低。原核生物和真核生物群落的结构组成随河流流向持续变化；例如，[具体物种1]和[具体物种2]的相对丰度随下游距离增加，而[具体物种3]和[具体物种4]则减少。一些原核生物分类群，如[具体分类群1]和[具体分类群2]，几乎仅存在于纯淡水环境中，而其他一些原核生物分类群，包括[具体分类群3]、[具体分类群4]、[具体分类群5]和[具体分类群6]，在纯淡水环境中几乎不存在。真核生物群落主要由[具体物种5]、[具体物种6]、[具体物种7]、[具体物种8]、[具体物种9]和[具体物种10]组成。通过非连续性群落成员分析（NCM分析），原核生物和真核生物群落分别被划分为优势、常见和稀有群落，结果显示，与优势和常见微生物群落相比，稀有群落的组装过程受随机过程影响更大，受物种扩散限制更小。总体而言，本研究为淡水河流向河口及海洋过渡过程中的微生物生态学提供了有价值的参考和新的视角。
