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附近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。 海峡地区包含多种沿海海洋栖息地。 近海岸地区毗邻美国城市化程度最高的地区之一（大洛杉矶地区），而公海则冲击着距离大陆 30 公里以内的海峡群岛。 圣佩德罗盆地是一个深水环境（约 890 m），氧气浓度非常低。 该项目的总体目标是对海洋中的微生物群落如何在空间（深度）和时间（以月至年的尺度）组织以及环境和生物因素如何塑造该组织有基本的了解。 该研究的基本前提是微生物物种的“行会”或“联合体”的存在，它们构成了构成浮游微生物群落的巨大多样性类群中的功能亚基。 形成这些群的微生物物种在功能上是相互依赖的，并且作为生态单元，随着环境条件的变化在时间和空间上相互替换。 该计划包括每月在四个深度进行采样，以记录河道中部采样站所有浮游微生物的丰度、生物量和物种组成。 采用各种微观和分子生物学方法来检查古菌、细菌和微真核生物（微藻、原生动物、微后生动物）的多样性。 该观测站的独特之处在于它需要对水体中的所有微生物（从病毒到最大的原生生物）进行评估。 整个微生物群落的遗传指纹是揭示微生物类群之间的营养作用和关系（捕食、互利共生、共生、寄生/感染）并生成有关这些物种之间相互依赖性的假设的主要工具。 实验研究涉及操纵食物网实验，以测试有关各种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，以确定微生物类群与环境参数之间的关系。该研究项目致力于对控制水生生态系统微生物群落结构的因素有一个基本的了解。 因此，这些结果对于预测自然界微生物活动介导的生物地球化学过程具有深远的影响。 该项目还包含强大的教育成分，旨在覆盖从小学生到研究生的各种学生。研究产生的信息被纳入主要研究者教授的本科生和研究生课程中，两种类型的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），该计划面向中学生和高中生，其中许多人是西班牙裔、非裔美国人或其他少数族裔，其中大多数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来实现的，该计划将该微生物观测站的研究纳入学习体验中，从而增强学生对环境科学、微生物学和自然世界的认识。 观测站主要研究人员的工作作为南加州大学微生物观测站网站（http://www.usc.edu/microbialobservatory）的一部分在互联网上公开发布。

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).