Microbial Community Structure and Expression of Functional Genes Involved in the Seasonal Cycling of DMSP in the Southern Ocean

南极洲附近的南大洋是一个以季节驱动的海洋浮游植物水华为特征的区域，这些浮游植物通常由产生大量二甲基磺酸丙酸酯(DMSP)的微藻物种主导。DMSP可以转化为化合物二甲基硫(DMS)，这是一种可以逃逸到大气中的分子，在大气中，它具有与区域云形成有关的强烈冷凝特性。DMSP的产生会影响海水中微生物群落的多样性和组成，而海水中微生物的种类和活性可能会影响DMSP/DMS的产量。该提案旨在研究DMSP在构建南极水域微生物群落方面的作用，以及这种结构可能如何影响DMSP的循环。该项目将利用南极研究向一系列受众(包括缅因州的高中生和本科生)介绍将微生物多样性和生物地球化学联系起来的概念和数据。该项目还将使K-8农村学校的教师和学生参与进来，并将允许与一名科学作家和插图画家合作，后者将加入实地小组。作者将以南大洋的经历为背景，制作一张海报和一本关于拟议中的研究和科学家研究极端环境的书。该项目将审查(1)南大洋DMSP的循环在多大程度上影响细菌和原生生物的组成和多样性；(2)相反，南大洋原生生物和细菌组合的组成和多样性是否影响DMSP循环的规模和速度；(3)海洋细菌季节性地和对DMSP的增加而表达DMSP降解基因；(4)通过量化这些结果来综合这些结果：(4)DMSP生产者和消费者及其捕食者的存在所产生的微生物网络，所有这些都参与南大洋DMSP的循环。这项工作将通过对夏季和秋季存在的不同微生物群落的野外采样期间，使用DMSP修正的自然样品进行连续生长实验来完成。来自分子(如16S/18S标签序列、DMSP循环基因转录本)和生物地球化学(如生物硫循环、细菌生产、微生物生物量)研究的数据将通过网络分析进行整合。

The Southern Ocean in the vicinity of Antarctica is a region characterized by seasonally-driven marine phytoplankton blooms that are often dominated by microalgal species which produce large amounts of dimethylsulfoniopropionate (DMSP). DMSP can be converted to the compound dimethylsulfide (DMS) which is a molecule that can escape into the atmosphere where it is known to have strong condensation properties that are involved in regional cloud formation. Production of DMSP can influence the diversity and composition of microbial assemblages in seawater and the types and activities of microbes in the seawater will likely affect the magnitude of DMSP\DMS production. The proposal aims to examine the role of DMSP in structuring the microbial communities in Antarctic waters and how this structuring may influence DMSP cycling. The project will leverage the Antarctic research to introduce concepts and data linking microbial diversity and biogeochemistry to a range of audiences (including high school and undergraduate students in Maine). The project will also engage teacher and students in rural K-8 schools and will allow a collaboration with a science writer and illustrator who will join the team in the field. The writer will use the southern ocean experience as the setting for a poster and a book about the proposed research and the scientists studying extreme environments. The project will examine (1) the extent to which the cycling of DMSP in southern ocean waters influences the composition and diversity of bacterial and protistan assemblages; (2) conversely, whether the composition and diversity of southern ocean protistan and bacterial assemblages influence the magnitude and rates of DMSP cycling; (3) the expression of DMSP degradation genes by marine bacteria seasonally and in response to additions of DMSP; and, to synthesize these results by quantifying (4) the microbial networks resulting from the presence of DMSP-producers and DMSP-consumers along with their predators, all involved in the cycling of DMSP in southern ocean waters. The work will be accomplished by conducting continuous growth experiments with DMSP-amended natural samples during field sampling of different microbial communities present in summer and fall. Data from the molecular (such as 16S/ 18S tag sequences, DMSP-cycle gene transcripts) and biogeochemical (such as biogenic sulfur cycling, bacterial production, microbial biomass) investigations will be integrated via network analysis.