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

综述：灰尘和矿物气溶胶是贫营养海洋表面沃茨微量和常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中发挥关键作用。然而，目前还不知道哪些灰尘成分刺激异养细菌，哪些细胞机制负责利用这些成分，以及这些细菌的活动如何影响海洋自养生物对灰尘衍生矿物质和营养物质的可用性和利用。了解这些因素是了解灰尘沉积如何影响碳循环以及预测热带海洋对灰尘沉积事件频率和强度未来变化的反应的关键。本项目的目的是研究在受控条件下，风成尘对热带海洋系统中异养微生物的具体影响。核心假设是，在贫营养热带系统中，数值较小的机会主义细菌是第一个响应者涌入的灰尘成分和响应主要是通过快速访问可溶性微量金属和限制营养物质沉积与撒哈拉沙漠灰尘。该项目将侧重于两个具体目标：1）量化接触灰尘后海洋微生物种群的群落结构、组成和转录活动的变化; 2）确定撒哈拉灰尘气溶胶中刺激或抑制弧菌（一种典型的机会性海洋异养菌群）生长和/或活动的关键成分。该研究将使用一系列受控实验，旨在通过宏基因组学、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），确定和量化异养微生物对灰尘沉积事件的反应。这种创新的方法将确定最关键的（活性）成分从灰尘气溶胶中浸出的微生物群落，以及阐明潜在的反应机制。鉴于沙尘气溶胶对地球化学循环的潜在巨大影响，但相对而言，（特别是在异养微生物部分）或确定了粉尘气溶胶的特定成分的相对重要性。一个详细的框架微生物的反应（侧重于机会异养）将有助于努力连接自养和异养处理。这一贡献是重要的，因为它将提供一个第一个端到端（化学生理生态）机制的海洋生物响应沙漠尘埃aerosols.Broader影响的途径：这项研究的结果将提供信息的一个经常被忽视的气候变化的组成部分，荒漠化的长期影响，这可能会影响整个海洋生物地球化学循环。此外，以弧菌为模型开展工作，将有助于解决灰尘沉积在全球海洋传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当地和区域会议以及国家（国际）会议上展示自己的作品。通过每个机构正在进行的项目，STEM代表性不足的群体的学生将被招募参加研究机会（以及进入研究生课程）。此外，通过参加格鲁吉亚海岸研究理事会，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将通过会议、与格鲁吉亚海岸研究理事会网站和邮件列表服务器的链接以及有针对性的出版物广泛传播给决策者和地方（沿海）利益攸关方。

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.