The Metabolic Response of Coastal Bacteria to Mortality-Derived Phytoplankton Dissolved Organic Matter

微生物通过溶解在周围水中的化学物质的交换相互作用。几十年的生物化学研究已经确定了微生物生长和健康所需的一小部分化学物质。这个有限的套件现在正在扩展基于质谱的新型分析工具。在这个项目中，重点将放在微生物死亡期间释放的化学物质上，特别关注病毒感染后的爆发细胞和原生动物（单细胞生物）放牧后的细胞残留物。这些化学物质并不是生产者故意释放的，但它们仍然会影响附近细菌的生长和健康，进而影响细菌将这些分子转化为二氧化碳的能力。拟议的比较褐潮藻死亡期间释放的化学物质的类型和反应性将有助于改进沿海海洋碳循环模型。本项目将直接资助两名研究生。倡议者计划开设两门课程，一门是质谱学课程，另一门是环境代谢组学课程。预计作为代谢组学课程发展的一部分，代谢组学的数据训练将成为课程的一部分。微生物群落对其周围环境的化学变化非常敏感，微生物群落的多样性随着生长基质和营养物质的组成而演变。因此，微生物之间的相互作用，通过溶解有机物（DOM）的环境，是全球碳循环的核心，因此值得重要的研究和调查。这个项目的重点是微生物死亡期间通过病毒裂解或原生动物放牧释放的分子。该项目使用基于质谱的新型工具，将微生物死亡产生的溶解有机物的组成与异养细菌再矿化这些基质的能力联系起来。将代谢参数和碳转化率作为DOM来源的函数，评估DOM类型对微生物生理和碳周转的影响。模式生物的实验室结果将与模式生物主导浮游生物群落的野外环境进行比较。该项目将产生一套分子，可用于未来的实验中作为微生物死亡率的标记，并将提供病毒裂解物和食草动物衍生的DOM的反应性之间的定量比较。这些结果将支持改进微生物网络的参数化及其对全球碳循环的影响。

Microbes interact with one another through the exchange of chemicals dissolved in their surrounding waters. Decades of biochemical research have identified a small suite of chemicals that are required by microbes for growth and well-being. This limited suite is now being expanded with novel analytical tools based on mass spectrometry. In this project, the focus will be on chemicals that are released during the death of microbes, with particular attention paid to burst cells after viral infections and to the remnants of cells after grazing by protozoa (single celled organisms). These chemicals are not intentionally released by their producers, but they can still affect the growth and well-being of nearby bacteria and in turn the bacteria's ability to convert these molecules to carbon dioxide. The proposed comparison of the types and reactivities of chemicals released during the death of a brown tide alga will help improve models of carbon cycling in the coastal ocean. Two graduate students will be supported directly by this project. The proponent plans to teach two classes, one a mass spectrometry course, the other an environmental metabolomics course. It is anticipated that as part of the evolution of the metabolomics course, data-training for metabolomics would become part of the course. Microbial consortia are exquisitely sensitive to chemical changes in their surroundings and the diversity of microbial communities evolves with the composition of available growth substrates and nutrients. Thus, interactions between microbes, through the milieu of dissolved organic matter (DOM), lie at the heart of the global carbon cycle and thus merit significant study and investigation. This project focuses on the molecules that are released during microbial mortality through viral lysis or protozoan grazing. Using novel mass spectrometry-based tools, this project links the composition of dissolved organic matter derived from microbial mortality with the ability of heterotrophic bacteria to remineralize these substrates. Metabolic parameters and carbon transformation rates will be determined as a function of DOM source to assess the impact of DOM type on microbial physiology and carbon turnover. Laboratory results from model organisms will be compared to field settings where the model organisms dominate planktonic communities. The project will generate a suite of molecules that can be used in future experiments as markers of microbial mortality and will provide quantitative comparisons between the reactivity of viral lysate and grazer-derived DOM. These results will support improved parameterizations of microbial networks and their impact on the global carbon cycle.