Collaborative Proposal: Vibrio as a model microbe for opportunistic heterotrophic response to Saharan dust deposition events in marine waters

概述：尘埃和矿物气溶胶是营养稀少的海洋表层水中微量和大量营养素的重要来源。越来越多的证据表明，异养微生物可能在处理沉积的矿物和营养物质方面发挥关键作用。然而，目前尚不清楚哪些粉尘成分刺激异养菌，哪些细胞机制负责这些成分的利用，以及这些细菌的活动如何影响海洋自养生物对粉尘衍生矿物和营养物质的利用和利用。了解这些因素对于了解尘埃沉积如何影响碳循环和预测热带海洋对未来尘埃沉积事件频率和强度变化的反应至关重要。本项目的目的是研究在受控条件下，风尘对热带海洋系统中异养微生物的特殊影响。中心假设是，在营养稀少的热带系统中，数量较少的机会性细菌是尘埃成分涌入的第一反应者，主要通过快速获取可溶的痕量金属和限制与撒哈拉尘埃沉积的营养物质来做出反应。该项目将侧重于两个具体目标：1)量化暴露在粉尘中的海洋微生物种群的群落结构、组成和转录活动的变化；2)确定撒哈拉尘埃气溶胶中刺激或抑制弧菌生长和/或活动的关键成分，弧菌是一个典型的机会主义海洋异养群体。这项研究将使用一系列对照实验，旨在通过元基因组学、转录组学以及大气和海洋生物地球化学技术，利用自然群落和模式细菌(弧菌)来确定和量化异养微生物对粉尘沉积事件的反应。这一创新的方法将确定从沙尘气溶胶中淋溶出来的对微生物群落最关键的(活性)成分，并阐明潜在的反应机制。智力上的优点：人们对沙尘气溶胶的生物反应非常感兴趣，因为它对生物地球化学循环的潜在影响很大，但研究反应机制(特别是在异养微生物组分中)或确定沙尘气溶胶特定成分的相对重要性的工作相对较少。微生物反应的详细框架(侧重于机会性异养生物)将有助于努力将自养和异养过程联系起来。这一贡献意义重大，因为它将为海洋生物对沙漠沙尘气溶胶的反应提供首批端到端(从化学到生理学再到生态学)的机械途径之一。广泛影响：这项研究的结果将提供关于气候变化的一个经常被忽视的组成部分的信息，即荒漠化的长期影响，它可能影响整个海洋的生物地球化学循环。此外，将弧菌作为模型进行工作将具有共同的好处，即解决尘埃沉积在全球海洋感染性病原体上升中可能发挥的作用。此外，该项目将为研究生、本科生和高中生提供培训和积极参与研究。所有学生都将有机会在地方和地区会议以及国家(国际)会议上介绍他们的工作。通过每个机构正在进行的项目，STEM代表性不足群体的学生将被招募以获得研究机会(并进入研究生课程)。此外，通过参加格鲁吉亚海岸研究理事会，将通过会议、与全球海洋研究理事会网站和名单的链接以及有针对性的出版物，向政策制定者和当地(沿海)利益攸关方广泛传播这项工作的成果以及海洋科学和气候变化方面的相关问题。

Overview: Dust and mineral aerosols are a significant source of micro and macronutrients to oligotrophic ocean surface waters. Evidence is growing that heterotrophic microbes may play key roles in processing deposited minerals and nutrients. Yet it is not known which components of dust stimulate the heterotrophic bacteria, which cellular mechanisms are responsible for the utilization of those components and how the activity of these bacteria affect the availability and utilization of dust-derived minerals and nutrients by marine autotrophs. Knowledge of these factors is key to understanding how dust deposition impacts carbon cycles and for predicting the response of tropical oceans to future changes in the frequency and intensity of dust deposition events. The objective of this project is to examine the specific effects of aeolian dust on heterotrophic microbes in a tropical marine system under controlled conditions. The central hypothesis is that in oligotrophic tropical systems numerically minor opportunistic bacteria are the first responders to influx of dust constituents and respond primarily by rapidly accessing soluble trace metals and limiting nutrients that are deposited with Saharan dust. The project will focus on two specific aims: 1) Quantify changes in community structure, composition and transcriptional activity among marine microbial populations upon exposure to dust, and 2) Identify key components in Saharan dust aerosols that stimulate or repress growth and/or activity in Vibrio, a model opportunistic marine heterotrophic group. The study will use a series of controlled experiments designed to identify and quantify heterotrophic microbial response to dust deposition events using both natural communities and model bacteria (Vibrio) through metagenomics, transcriptomics and atmospheric and marine biogeochemical techniques. This innovative approach will identify the most critical (reactive) components leached from dust aerosols on the microbial community as well as elucidate potential mechanisms of response.Intellectual Merit: There is great interest in the biological response to dust aerosols given its potentially large influence on biogeochemical cycling, but there has been relatively little work that has addressed the mechanisms of response (especially among the heterotrophic microbial fraction) or identified the relative importance of specific constituents of dust aerosols. A detailed framework for microbial response (focusing on opportunistic heterotrophs) will facilitate efforts to link autotrophic and heterotrophic processing. This contribution is significant because it will provide one of the first end-to-end (chemistry to physiology to ecology) mechanistic pathways for marine biological response to desert dust aerosols.Broader Impacts: The outcomes of this research will provide information on an often overlooked component of climate change, the long range effects of desertification, which could impact biogeochemical cycling throughout the oceans. Furthermore, working with Vibrio as a model will have the co-benefit of addressing the possible role of dust deposition on the global rise of a marine infectious agent. Additionally, this project will provide graduate, undergraduate and high school students with both training and active participation in research. All students will have opportunities to present their work at local and regional meetings as well as national (international) conferences. Through on-going programs at each institution, students from STEM under-represented groups will be recruited for research opportunities (and for entry into graduate programs). Additionally, through participation in the Georgia Coastal Research Council results of this work, and related issues in marine science and climate change, will be broadly disseminated to policy-makers and local (coastal) stakeholders through meetings, links to the GRGC website and listserv and targeted publications.