The fate of lysis products of picocyanobacteria contributes to marine humic-like chromophoric dissolved organic matter

摘要本文主要研究海洋中有色溶解有机物(CDOM)的来源和组成。CDOM是水中吸收阳光的一部分。这种材料很重要，因为它能过滤有害的紫外线辐射。科学家用它来跟踪海洋中碳的移动和其他重要的生物和化学过程。生活在公海中的生物，如藻类，已被证明是CDOM的来源，但这些藻类天然产物的化学成分仍有待发现。最近对普通藻类的研究结果表明，病毒可能会分解藻类细胞，释放出看起来像CDOM的物质。这项研究将使用新的工具来找出病毒和藻类是否正在创造这种材料，并研究其化学组成。该项目将支持两名研究生，并通过NSF本科生研究体验(REU)计划为本科生提供暑期实习机会。调查员将参加一系列教育和外联活动。海洋中海洋CDOM的来源和结构性质尚不清楚，仍是一个有争议的主题。海洋中CDOM的原位来源已被提出，其中一些已得到证实，但到目前为止，还没有人能解释所谓的“类腐殖质”CDOM组分的普遍存在。该组分的独特特征包括其在紫外线-可见光(UV-VIS)吸光度方面的不同寻常的指数行为，吸光度远远超过400 nm，以及荧光光谱中的大斯托克位移。微囊藻在世界海洋中普遍存在，占自养海洋初级生产力的50%。初步结果表明，微囊藻、聚球藻和原氯球菌经病毒诱导裂解后释放的CDOM与全球观察到的海洋CDOM的“腐殖质样”外观相符。本研究的重点是不同菌株的聚球藻和原氯球菌的病毒裂解DOM(VDOM)的光学性质和分子组成的表征，以及先前研究中显示的也释放CDOM的毛霉菌。将调查太平洋和大西洋中苦杏仁细菌的化学特征信息与元基因组学和转录组数据之间的联系。这项研究包括长期培养实验，以确定苦味蓝杆菌衍生的CDOM的持久性，以及与孵化期间VDOM降解相关的微生物群落和过程(基因表达)的变化。该奖项反映了NSF的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

AbstractThis study focuses on the sources and composition of colored dissolved organic matter (CDOM) in the ocean. CDOM is a part of water that absorbs sunlight. This material is important because it filters out harmful ultraviolet radiation. Scientists use it to track the movement of carbon and other important biological and chemical processes in the ocean. Organisms such as algae living in the open ocean have been shown to be sources of CDOM, but the chemical composition of these algal natural products remains to be discovered. Recent results from studying common algae show that viruses may break down algal cells and release material that looks like CDOM. This study will use new tools to find out if viruses and algae are creating this material and study its chemical makeup. This project will support two graduate students and provide summer internships for undergraduates through the NSF Research Experiences for Undergraduates (REU) program. The investigators will participate in a range of education and outreach activities.The sources and structural nature of marine CDOM within the oceans remain unclear and continue to be a subject of debate. Marine in situ sources of CDOM have been suggested and some have been confirmed, but thus far none could explain the ubiquitous appearance of the so called "humic-like" CDOM component. Unique features of this component include its unusual exponential behavior in ultraviolet-visible (UV-Vis) absorbance with the absorbance extending well above 400 nm, and the large Stoke's shift in fluorescence spectroscopy. Picocyanobacteria are ubiquitous in the World's Oceans and make up 50 % of the autotrophic marine primary production. Preliminary results showed that the picocyanobacteria Synechococcus and Prochlorococcus release CDOM that matched the "humic-like" appearance of globally observed marine CDOM after virus-induced lysis. The main focus of this study is the characterization of the optical properties and molecular composition of viral-lysed DOM (VDOM) from different strains of Synechococcus and Prochlorococcus and additionally Trichodesmium which was shown in a previous study to also release CDOM. Associations between the chemical characterization information and metagenomics and transcriptomics data will be investigated for picocyanobacteria in the Pacific and Atlantic Oceans. This study includes long-term incubation experiments to determine the persistence of picocyanobacteria-derived CDOM as well as changes in microbial communities and processes (gene expression) that are related to the degradation of VDOM during the incubation period.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.