Microbial Observatories: Salt Marsh Microbes and Microbial Processes: Sulfur and Nitrogen

这个微生物观测站位于马萨诸塞州东北部的梅子岛长期生态研究(LTER)地点，它确定了盐沼中的微生物和微生物群落，并确定了它们在控制主要生态系统过程中的作用。该天文台项目由来自海洋生物实验室(MBL)、伍兹霍尔海洋研究所和西北大学的科学家组成，为LTER研究改变无机营养供应和有机物的质量和数量对河口营养结构的影响增加了微生物及其生态学的知识。LTER研究获得了关于其调查的过程和控制参数背后的微生物群落的详细知识；微生物观测站使用LTER数据将微生物群落置于其物理和化学环境的更大背景中。在盐沼沉积物中，氮和硫的循环影响着盐沼的所有生物地球化学循环，而硫酸盐还原则主导着分解。因此，天文台项目重点关注参与氮硫循环的微生物，特别关注硝化作用和硫酸盐还原作用。这种关注是可能的，因为这些研究人员带来了一套用于培养、分子检测和鉴定硝化细菌和硫酸盐还原细菌的工具。微生物观测站开展以下活动：1.通过培养和测序技术鉴定微生物和微生物群落，2.用培养方法和核酸变性梯度凝胶电泳法(DGGE)调查群落结构的季节变化，3.用rRNA杂交技术将负责特定过程的功能基因和微生物种群联系起来，4.将各种种群的存在和活动与盐沼主要过程的生态测量相关联。使用功能基因和rRNA杂交技术的分子调查与硫酸盐还原和氮循环的LTER措施相关。碳源是通过使用细菌特有的磷脂脂肪酸增量13C的技术来识别的。盐沼是微生物构建和塑造整个生态系统的最好例子之一。蓝藻是盐沼中的先驱生物；它们在泥滩上启动微生物群落，防止侵蚀，捕获沉积物颗粒，并抬高沉积物表面。当高等植物在该地点定居时，微生物固定氮，循环有机物和养分，氧化硫化物，并为更高的营养水平提供食物。盐沼仍然是基础微生物和生物地球化学研究的重要模式。这些系统很容易访问。它们的高加工速度、大量和多样化的功能不同的微生物种群以及陡峭的化学和微生物梯度使科学家能够了解微生物相互作用和化学循环是如何工作的。例如，我们对海洋环境中硫酸盐还原过程和微生物学的许多见解都来自对盐沼的研究。盐沼在教学和教育中的价值已经确立。在伍兹霍尔的MBL学习微生物多样性课程的学生，与这个微生物观测站有关，利用盐沼作为“微生物雨林”来分离和鉴定各种各样的微生物。

9977897HobbieThis Microbial Observatory at the Plum Island Long Term Ecological Research (LTER) site in northeastern Massachusetts identifies microbes and microbial communities in the salt marsh and determines their role in controlling major ecosystem processes. The observatory project, staffed by scientists from the Marine Biological Laboratory (MBL), the Woods Hole Oceanographic Institution, and Northwestern University, adds knowledge of the microbes and their ecology to the LTER research on the effects of changing inorganic nutrient supply and the quality and quantity of organic matter on estuarine trophic structure. The LTER research gains detailed knowledge about the microbial communities underlying the processes and control parameters which it investigates; the Microbial Observatory uses LTER data to place microbial communities into the larger context of their physical and chemical environment. In the salt marsh sediments, nitrogen and sulfur cycles influence all of the salt marsh biogeochemical cycles while sulfate reduction dominates decomposition. Therefore, the Observatory Project focuses on the microbes involved with the nitrogen and sulfur cycle with special attention to nitrification and sulfate reduction. This focus is possible because these investigators bring a suite of tools for culturing, molecular detection, and identification of nitrifying and sulfate reducing bacteria. The Microbial Observatory carries out the following activities: 1. identifies the microbes and microbial communities by means of culture and sequencing techniques, 2. investigates the seasonal changes in the community structure with culture methods and with denaturing gradient gel electrophoresis (DGGE) of nucleic acids, 3. links functional genes and microbial populations responsible for specific processes with rRNA hybridization techniques, and 4. correlates the presence and activity of various populations with ecological measurements of major processes in the salt marsh. Molecular surveys using functional genes and rRNA hybridization techniques are correlated with LTER measures of sulfate reduction and the nitrogen cycle. Carbon sources are identified with techniques using the delta 13C of phospholipid fatty acids specific to bacteria. Salt marshes provide one of the best examples of a site where microbes build and shape an entire ecosystem. Cyanobacteria are the pioneer organisms in salt marshes; they initiate microbial mat communities on mudflats that prevent erosion, trap sediment particles, and elevate the surface of the sediments. When higher plants colonize the site, the microbes fix nitrogen, recycle organic matter and nutrients, oxidize sulfides, and provide food for higher trophic levels. Salt marshes continue to be important models for basic microbiological and biogeochemical research. These systems are easily accessible. Their high process rates, large and diverse populations of functionally distinct microbes, and steep chemical and microbial gradients allow scientists to understand how microbial interactions and chemical cycles work. For example, many of our insights into the process and microbiology of sulfate reduction in the marine environment have come from the study of salt marshes. The value of salt marshes in teaching and education is well established. Students of the Microbial Diversity Course at the MBL in Woods Hole, associated with this Microbial Observatory, use the salt marsh as a "Microbial Rainforest" for the isolation and identification of a wide diversity of microbes.