The key role of DOM in regulating microbial diversity, community structure and organic carbon cycling in arctic lakes

DOM在调节北极湖泊微生物多样性、群落结构和有机碳循环中的关键作用

• 批准号: NE/J022063/1
• 负责人: Graham Underwood
• 金额: $ 50.37万
• 依托单位: University of Essex
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2013
• 资助国家: 英国
• 起止时间: 2013 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FJ022063%2F1
• 关键词: key; role; DOM; regulating; microbial

The Arctic is a considerable organic carbon store (~1672 Pg) and the terrestrial and aquatic processing of this C pool is essentially mediated by microorganisms. Understanding the mechanisms regulating the diversity and structure of functionally-important microbial communities is urgently required for predicting the ecological impacts of rapidly changing environments, such as a warming Arctic. All aquatic ecosystems (lakes, rivers, the oceans) contain very substantial amounts of dissolved organic matter (DOM). The amount of DOM can exceed the amount of carbon contained in living organisms (plants, animals, microbes, etc.). This accumulated organic matter is the product of photosynthesis, consumption and degradation pathways, and can contain a range of material, from compounds that are 100's of years old, and are difficult for bacteria to break down, to recently produced organic matter that may have leaked from living algal cells as they photosynthesise, which can quickly be used by bacteria and other microorganisms. This microbial action generates food for other organisms, and promotes nutrient regeneration, and recycles the organic matter back into food chains. Other DOM can stick together and become buried in sediments and locked away for geological periods of time. The huge quantities of DOM present in aquatic systems mean that understanding its characteristics and dynamics (biogeochemical cycling) is necessary to understand individual systems and to generate accurate regional carbon budgets. There is an ongoing debate in ecology as to how DOM interacts with the microbial communities that play such an important part in DOM biogeochemistry, and what aspects of DOM help shape the microbial community (e.g. is it species rich, or species poor, mainly active or mainly inactive). Understanding the relationship between species diversity and biogeochemical cycling in different ecosystems is a priority topic for NERC. New experimental approaches and methods mean these questions can now be addressed. This project is investigating these concepts in a system of lakes in West Greenland. These lakes have a range of DOM concentrations, and are being influenced by global change processes such as increased atmospheric nutrient loading and annual warming. Arctic lakes are extremely important in their regional ecology; they occupy significant land area and can act as annual carbon sinks or carbon sources, depending on their characteristics. We will characterise the different DOM components of the water columns of a set of lakes selected to provide a controlled gradient of conditions, and determine the seasonal cycles of accumulation and loss of DOM. In parallel, we will use new molecular biology tools to identify and quantify the diverse microbial communities involved in these processes. We will be able to determine the relationship between microbial community diversity and activity, and how this is influenced by the types of DOM present. We will also conduct experiments to establish which DOM are the most difficult and most easy for particular microbes to breakdown, and whether such processes are influenced by nutrients such as nitrogen. These results will help to assess how the ecology lakes in arctic regions will change over the next few decades, as well as providing important information on the relationships between DOM biogeochemistry and microbial diversity and activity that will be applicable to other aquatic systems. These new data will also contribute to the development of theories of how microbial community are structured, and whether they follow rules determined for larger organisms, or have unique characteristics.

北极是一个相当大的有机碳库（~1672 Pg），该碳库的陆地和水生处理基本上是由微生物介导的。为了预测快速变化的环境（例如北极变暖）的生态影响，迫切需要了解调节具有重要功能的微生物群落的多样性和结构的机制。所有水生生态系统（湖泊、河流、海洋）都含有大量溶解有机物 (DOM)。 DOM 的量可以超过生物体（植物、动物、微生物等）中所含的碳量。这种积累的有机物是光合作用、消耗和降解途径的产物，并且可能包含一系列物质，从具有数百年历史且难以被细菌分解的化合物，到最近产生的有机物，这些有机物可能是活藻细胞在光合作用时泄漏的，可以很快被细菌和其他微生物利用。这种微生物作用为其他生物体产生食物，促进营养再生，并将有机物回收回食物链。其他 DOM 可以粘在一起并埋在沉积物中并在地质时期内被锁定。水生系统中存在大量的 DOM，这意味着了解其特征和动态（生物地球化学循环）对于了解各个系统并生成准确的区域碳预算是必要的。生态学界一直在争论 DOM 如何与在 DOM 生物地球化学中发挥如此重要作用的微生物群落相互作用，以及 DOM 的哪些方面有助于塑造微生物群落（例如，它是物种丰富还是物种贫乏、主要活跃还是主要不活跃）。了解不同生态系统中物种多样性与生物地球化学循环之间的关系是 NERC 的优先课题。新的实验方法和方法意味着这些问题现在可以得到解决。该项目正在西格陵兰岛的湖泊系统中研究这些概念。这些湖泊具有不同的 DOM 浓度，并受到全球变化过程的影响，例如大气养分负荷增加和年度变暖。北极湖泊在其区域生态中极其重要；它们占据大量土地面积，根据其特性可以充当年度碳汇或碳源。我们将表征一组湖泊水柱的不同 DOM 成分，这些湖泊被选择来提供受控的条件梯度，并确定 DOM 积累和损失的季节周期。与此同时，我们将使用新的分子生物学工具来识别和量化这些过程中涉及的不同微生物群落。我们将能够确定微生物群落多样性和活动之间的关系，以及这种关系如何受到存在的 DOM 类型的影响。我们还将进行实验，以确定哪些 DOM 对特定微生物来说最难和最容易分解，以及这些过程是否受到氮等营养物质的影响。这些结果将有助于评估北极地区的生态湖泊在未来几十年将如何变化，并提供有关 DOM 生物地球化学与微生物多样性和活动之间关系的重要信息，这些信息将适用于其他水生系统。这些新数据还将有助于微生物群落结构理论的发展，以及它们是否遵循为大型生物体确定的规则，或具有独特的特征。