MO: Assembly of Marine Microbial Communities

南加州大学微生物观测站成立于2000年。该观测站的研究重点是对南加州海岸外圣佩德罗海峡和盆地的一个研究地点的微生物多样性和微生物群落组成进行调查。海峡地区包括各种沿海海洋栖息地。近海地区与美国城市化程度最高的地区之一(大洛杉矶)接壤，而公海水域冲击着延伸到大陆30公里以内的海峡岛群岛。圣佩德罗盆地是一个深水环境(约890米)，氧气浓度非常低。该项目的首要目标是从根本上了解海洋中的微生物群落是如何在空间上(随深度)和在时间上(按月到年的尺度)组织的，以及环境和生物因素如何塑造这一组织。这项研究的基本前提是，在组成浮游微生物群落的巨大多样性的分类群中，存在构成功能亚单位的微生物物种的“行会”或“联盟”。形成这些行会的微生物物种在功能上相互依存，并作为生态单位，随着环境条件的变化在时间和空间上相互取代。该方案包括每月在四个深度进行采样，以记录中航道采样站所有浮游微生物的丰度、生物量和物种组成。各种显微镜和分子生物学方法被用来研究古生物、细菌和微型真核生物(微藻、原生动物、后生动物)的多样性。该天文台的独特之处在于，它需要对水柱中的微生物(从病毒到最大的原生生物)的全谱进行评估。总微生物群落的遗传指纹图谱是揭示微生物类群(捕食、互惠、共生、寄生/感染)之间的营养作用和关系，并产生关于这些物种之间相互依存关系的假设的主要工具。实验研究包括操纵性食物网实验，以检验关于不同微生物物种之间的关系和相互作用的假设。这些数据支持广泛的统计分析，以确定微生物类群之间的关系，以及与环境参数的关系。本研究计划致力于对控制水生态系统中微生物群落结构的因素有一个基本的了解。因此，这一结果对于预测自然界微生物活动所介导的生物地球化学过程具有深远的影响。该项目还纳入了一个强有力的教育内容，旨在惠及从小学生到研究生的各类学生。研究产生的信息被纳入主要研究人员教授的本科生和研究生课程，这两类学生都积极参与研究。此外，该项目支持的主要研究人员和研究生直接参与正在进行的教师教育计划(海洋科学教育卓越中心；COSEE-WEST)，该计划惠及初中生和高中生，他们中的许多人是西班牙裔、非裔美国人或其他少数民族，他们中的大多数人在经济上处于不利地位。这一教育/推广目标是通过现有的教师增强和学生充实计划实现的，该计划将来自该微生物观测站的研究纳入学习体验，以提高学生对环境科学、微生物学和自然世界的认识。作为南加州大学微生物观测站网站http://www.usc.edu/microbialobservatory).的一部分，天文台首席研究人员的工作在互联网上进行了专题报道并向公众开放

The USC Microbial Observatory was established in 2000. The research focus of this observatory is an investigation of the microbial diversity and microbial community composition at a study site in the San Pedro Channel and Basin off the coast of southern California. The Channel area encompasses a diversity of coastal ocean habitats. The near-coast region borders one of the most highly urbanized areas of the country (greater Los Angeles) while open ocean waters impinge on the Channel Island archipelago that extends to within 30 km of the mainland. The San Pedro Basin is a deep-water environment (approximately 890 m) that exhibits very low oxygen concentration. The overarching objective of this project is the derivation of fundamental understanding of how microbial communities in the ocean are organized spatially (with depth) and temporally (at scales of months-to-years), and how environmental and biological factors shape this organization. The basic premise of the research is that "guilds" or "consortia" of microbial species exist that constitute functional subunits within the huge diversity of taxa that comprise planktonic microbial communities. The microbial species forming these guilds are functionally interdependent, and act as ecological units that replace one another in time and space as environmental conditions change. The program consists of monthly sampling at four depths in order to document the abundance, biomass and species composition of all planktonic microorganisms at the mid-channel sampling station. A variety of microscopical and molecular biological approaches are employed to examine archaeal, bacterial and microeukaryote (microalgal, protozoan, micrometazoan) diversity. The observatory is unique in that it entails an assessment of the complete spectrum of microorganisms (from viruses to the largest protists) in the water column. Genetic fingerprinting of the total microbial community is the primary tool for revealing the trophic roles and relationships among microbial taxa (predation, mutualism, commensalism, parasitism/infection), and to generate hypotheses on the interdependences among these species. Experimental studies involve manipulative food web experiments to test hypotheses concerning the relationships and interactions among the various microbial species. The data support extensive statistical analyses to identify relationships between microbial taxa, and with environmental parameters.This research program strives to develop a fundamental understanding of the factors controlling the structure of microbial communities in aquatic ecosystems. Therefore, the results have far-reaching consequences for predicting biogeochemical processes mediated by microbial activities in nature. The project also incorporates a strong educational component aimed at reaching students ranging from elementary school children to graduate students. The information resulting from the research is incorporated into undergraduate and graduate courses taught by the principal investigators, and both types of students participate actively in the research. In addition, the principal investigators and graduate students supported by this project participate directly in an ongoing teacher education program (Centers for Ocean Science Education Excellence; COSEE-West) that reaches middle and high school students, many of whom are Hispanic, African-American or other ethnic minorities and most of whom are economically disadvantaged. This education/outreach goal is accomplished through an existing teacher enhancement and student enrichment program that incorporates the research from this microbial observatory into a learning experience that enhances student awareness of environmental science, microbiology and the natural world. The observatory principal investigators work is featured and publicly available on the internet as a part of the USC Microbial Observatory Website at http://www.usc.edu/microbialobservatory).