Collaborative Research: Formation of Modified Biochemicals and their Contribution to Dissolved Organic Nitrogen in Marine Ecosystems

尽管溶解有机氮是世界海洋中最大的还原氮储存库，但人们对其来源、反应活性和长期去向知之甚少。最近的研究表明，高相对分子质量的溶解有机氮主要是具有酰胺键的化合物--就像在生物来源的蛋白质分子中发现的那样。这些酰胺的来源尚不清楚，但蛋白质和几丁质(氨基酸和糖单体的反应产物)被认为是主要的候选者。在这项研究中，马里兰大学环境研究中心的有机地球化学家和特拉华大学的微生物生态学家将联合人才研究这种DON的形成机制。有三个主要的研究问题：(1)蛋白质或甲壳素是否被修饰成无法识别的氨基酸或氨基糖聚合物？(2)这些化合物周围的物理基质是增强还是抑制化学/微生物过程？(3)这些修饰的副产品对特拉华州河口和沿海海洋中的高分子量溶解和颗粒状有机物有何贡献？将采用各种最先进的有机分析和微生物生物化学技术来解决这些问题。研究人员预计，这项研究将极大地扩大我们对海洋水域中这些含氮物质存在和持续存在的过程的理解。

ABSTRACTOCE-9907069 & OCE-9908808Although dissolved organic nitrogen is known to be the largest reservoir of reduced nitrogen in the world ocean, little is known about its origin, reactivity, and long-term fate. Recent research indicates that high-molecular-weight dissolved organic nitrogen is dominated by compounds with amide linkages - like those found in biogenic protein molecules. The sources of these amides are unknown, but proteins and chitins (reaction products between amino acid and sugar monomers) are considered prime candidates. In this study, an organic geochemist at the University of Maryland Center for Environmental Studies and a microbial ecologist at the University of Delaware will combine talents to investigate the mechanisms by which this DON is formed. There are three major research questions: (1) Is protein or chitin modified to forms unrecognizable as amino acid or amino sugar-containing polymers?; (2) Does the physical matrix surrounding these compounds enhance or inhibit chemical/microbiological processes?; and (3) What is the contribution of these modified byproducts to the high molecular weight dissolved and particulate organic matter in the Delaware estuary and coastal ocean? A variety of state-of-the art techniques of organic analysis and microbial biochemistry will be employed to address these questions. The investigators anticipate that this study will significantly expand our understanding of the processes responsible for the presence and persistence of these nitrogenous substances in marine waters.