Collaborative Research: Marine priming effect - molecular mechanisms for the biomineralization of terrigenous dissolved organic matter in the ocean

合作研究：海洋启动效应——海洋中陆源溶解有机物生物矿化的分子机制

• 批准号: 1464392
• 负责人: Robert Spencer
• 金额: $ 14.98万
• 依托单位: Florida State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-09-04 至 2018-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1464392&HistoricalAwards=false
• 关键词: Collaborative; Research; Marine; priming; effect; Collaborative; Research; Marine; priming; effect

Overview: Large fluxes of apparently refractory terrigenous dissolved organic matter (t-DOM) are transported through rivers to the coast each year, yet there are vanishingly low traces of t-DOM in the oceans. The removal of t-DOM is central to the global carbon cycle, yet the mechanisms that drive removal remain poorly understood. In soils, the presence of labile organic compounds is known to enhance the remineralization of recalcitrant compounds, a phenomenon known as the priming effect (PE). The PE is quantitatively important in soil systems, but has received little attention in aquatic systems despite its potential to explain C mineralization patterns at the land-sea interface. This project investigates the magnitude of PE in the coastal ocean and the metabolic and ecological mechanisms that give rise to it. It focuses on the microbial communities of US Atlantic Ocean coastal marshes. In these systems, river-borne t-DOM provides a particularly valuable and tractable model for evaluating the magnitude of the PE. The study utilizes a well-characterized DOM standard collected from a Georgia river as the model t-DOM material in a series of laboratory experiments with natural coastal microbial communities and cultures of heterotrophic marine bacteria of the Roseobacter lineage. Roseobacters are particularly appropriate biological models for this work as they are abundant in southeastern US coastal zones and are known to catabolize lignin and other plant-derived aromatic compounds. Long-term (60 day) incubation experiments will track the PE resulting from addition of labile DOM of differing chemical complexity. Changes in lignin phenols will be the primary measure of the influence of PE on t-DOM degradation, but the research also monitors a broader suite of aromatic compounds represented by optical properties and identified by high-resolution mass spectrometry. Measurements of the microbial response to added labile organic matter, via extracellular enzyme activities, bacterial production, community composition and gene transcript analysis, will reveal the biological mechanisms responsible for the PE. Experiments using Roseobacter strains will allow detailed investigation of the relationship between metabolic pathways, specific bacteria, and organic carbon mineralization in a well-defined experimental system. Data on gene expression, microbial activity, and DOM transformations from the lab experiments will be integrated to elucidate the specific metabolic pathways invoked as part of the PE and guide development of molecular tools to track genetic signatures along a river to coastal ocean transect in the final year of the project.Intellectual Merit: The role of heterotrophic microorganisms in remineralizing t-DOM at the land-sea interface is a central question in biological oceanography. Components of t-DOM, principally lignin, are refractory in the sense that degradation rates are typically slow relative to other biomolecules, and yet lignin is effectively removed somewhere between land and the open ocean. The project will determine whether priming plays a role in the rapid removal of t-DOM in the coastal ocean, provide evidence for the types of labile organic matter most effective as priming agents, and attempt to discover the metabolic pathways by which the PE is mediated. These studies have the potential to reveal conserved and predictable metabolic responses that may contribute to regulation of the transformation and turnover of naturally occurring semi-labile/refractory DOM in marine environments. As climate change is likely to affect fluxes of both terrigenous carbon and nutrients to the coastal ocean, understanding the magnitude and mechanisms of PE will be necessary to predict the geochemical consequences of these changing fluxes.Broader Impacts: The project will directly support the interdisciplinary and multi-institutional training of two graduate students and several undergraduate students. Training opportunities under a recently funded Research Experiences for Undergraduates (REU) program at UTK will be leveraged and extended to local UTK undergraduates participating in the project. Funding of this project will also provide support for research faculty to continue to develop an outreach program at a primarily minority high school in Newark NJ. Finally, all PIs will continue to disseminate their research results in presentations, papers and other forms on a timely basis.

概述：每年通过河流运输到海岸的大量耐火意大利地溶解有机物（T-DOM）的大量通量，但海洋中T-DOM的痕迹消失了。 T-DOM的去除是全球碳循环的核心，但是驱动清除的机制仍然很少理解。在土壤中，已知存在不稳定的有机化合物的存在可以增强顽固化合物的再矿化，这种现象称为启动效应（PE）。 PE在土壤系统中很重要，但是尽管它有可能在土地海界面解释C矿化模式，但在水生系统中很少关注。该项目研究了沿海海洋中PE的大小以及引起它的代谢和生态机制。它着重于美国大西洋沿海沼泽的微生物群落。在这些系统中，河流T-DOM为评估PE的幅度提供了一个特别有价值且可拖延的模型。这项研究利用了从佐治亚河收集的特征良好的DOM标准作为T-DOM模型材料，其中一系列具有自然沿海微生物群落和异养生植物菌群的培养物的实验室实验。玫瑰杆菌是这项工作的特别合适的生物模型，因为它们在美国东南部沿海地区丰富，并且众所周知可以分解木质素和其他植物衍生的芳族化合物。长期（60天）的孵育实验将跟踪由于添加不同化学复杂性不稳定的DOM而导致的PE。木质素苯酚的变化将是PE对T-DOM降解影响的主要度量，但是该研究还监视了以光学性质代表并通过高分辨率质谱鉴定的更广泛的芳香族化合物。通过细胞外酶活性，细菌产生，社区组成和基因转录分析的微生物反应对增加的不稳定有机物的测量将揭示负责PE的生物学机制。使用玫瑰杆菌菌株的实验将允许详细研究代谢途径，特异性细菌和有机碳矿化之间的关系。有关基因表达，微生物活性和从实验室实验的DOM转化的数据，将集成以阐明作为PE的特定代谢途径作为PE的一部分，并指导分子工具的开发，以跟踪沿河到沿海地区的遗传特征到沿海海洋的遗传特征，在项目的最后一年。生物海洋学。 T-DOM（主要是木质素）的成分是难治性的，因为相对于其他生物分子，降解率通常很慢，但木质素被有效地移除了土地和开阔的海洋之间。该项目将确定启动是否在沿海海洋中的T-DOM快速去除中起作用，为不稳定的有机物类型提供了最有效的启动剂的证据，并试图发现PE介导的代谢途径。这些研究有可能揭示保守和可预测的代谢反应，这可能有助于调节海洋环境中天然发生的半光活性/难治性DOM的转化和周转。由于气候变化可能会影响陆源碳和养分对沿海海洋的通量，因此了解PE的大小和机制对于预测这些不断变化的通量的地球化学后果是必要的。Boader的影响：该项目将直接支持跨学科和多个研究生的跨学科和多机构培训，并支持两名研究生和几个不足的学生。 UTK的本科生（REU）计划（REU）计划的培训机会将得到利用，并扩展到参加该项目的当地UTK本科生。该项目的资金还将为研究学院提供支持，以继续在Newark NJ的主要少数族裔高中制定外展计划。最后，所有PI将继续在演讲，论文和其他形式中及时传播其研究结果。