Metabolic activity of planktonic archaea and their contribution to the marine carbon cycle

浮游古菌的代谢活动及其对海洋碳循环的贡献

• 批准号: 289647370
• 负责人: Professor Dr. Martin Könneke
• 金额: --
• 依托单位: Institut für Chemie und Biologie des Meeres (ICBM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/289647370?language=en
• 关键词: Metabolic; activity; planktonic; archaea; their

The oceans cover about three quarters of the Earth and the water colmn, with an average depth of 4000m, represents one of the World s largest habitate for life. Over the last two decades it has became evident that microorganisms of the domain Archaea are abundant and ecological relevant members of the oceanic picoplankton in all depth. The chemolithoautotrophic life style of the most abundant marine archaeal group derived from the successful cultivation in pure culture. By date all members of this novel phylum Thaumarchaeota generate energy by the aerobic conversion of ammonia to nitrite and fix CO2 as primary carbon source. Exhibiting extremely high subtrate affinity and operating the most energy-efficient aerobic CO2 fixation pathway, marine ammonia-oxidizing archaea are perfectly suited to thrive in nutrient-poor environments as typically for most of the ocean water. Because of their physiology and high abundance ammonia-oxidizing archaea have been recognized as predominant nitrifyers and important primary produzers in the Ocean. Based on its ubiquitous distribution I hypothesis that the recently characterized thaumarchaeal variant of the hydroxypionate/hydroxybutyrate cycle (HP/HB cycle) is the most important CO2 fixation pathway in the dark realm of the ocean below the photic zone. Previous modells quantifying the pelagic chemoautrotrophy flux are mostly based on the out-dated assumption that bacterial and not archaeal nitrifyers are the main contributors. Hence, the research project proposed here aims to re-evaluate the contribution of planktonic archaea to the marine C-cycle and to pelagic chemoautotrophy using novel, organism specific analytical tools. For instance, the in situ activity and turn over rates of thaumarchaeal ammonia oxidizers will be determined by measuring the incorporation of stable C and H isotopes into diagnostic thaumarchaeal lipids. In combination with the distribution of novel marker genes coding for the thaumarchaeal HP/HB cycle and application of the NanoSIMS/HIS-SIMS technology we will investigate the actual contribution of chemolithoautotrophic archaea to the pelagic primary production. Furthermore, I propose to cultivate members of the yet uncharacterized deep sea thaumarchaeota clade at near-environmental conditions to get access to their physiological and genetic characteristics. In sum, this research project aims to obtain novel findings on the biology of one of the World s most abundant organism group and to contribute to the biogeochemical understanding of the marine C-cycle.

海洋覆盖了地球的四分之三，平均深度为4000米的水柱是世界上最大的生命栖息地之一。在过去的二十年里，很明显，微生物领域的微生物是丰富的，在所有深度的海洋微型浮游生物的生态相关成员。最丰富的海洋古菌群的化能自养生活方式来源于纯培养的成功培养。到目前为止，这个新的Thaumarchaeota门的所有成员都通过将氨有氧转化为亚硝酸盐并固定CO2作为主要碳源来产生能量。海洋氨氧化古菌表现出极高的底物亲和力，并运行最节能的有氧CO2固定途径，非常适合在营养不良的环境中茁壮成长，这通常适用于大多数海水。氨氧化古菌因其生理特性和高丰度而被认为是海洋中主要的硝化菌和重要的初级生产菌。基于其无处不在的分布我的假设，最近表征thaumarchaeal的羟基丙酸/羟基丁酸循环（HP/HB循环）的变体是最重要的CO2固定途径在黑暗的领域的海洋下面的透光区。以前的模型量化的浮游化学自养通量大多是基于过时的假设，细菌，而不是古细菌硝化细菌的主要贡献者。因此，这里提出的研究项目的目的是重新评估的海洋碳循环和浮游化学自养的贡献，使用新的，生物体的具体分析工具。例如，将通过测量稳定的C和H同位素掺入诊断性嗜热古细菌脂质中来确定嗜热古细菌氨氧化剂的原位活性和转化率。结合编码thaumarchaeal HP/HB循环的新标记基因的分布和NanoSIMS/HIS-SIMS技术的应用，我们将调查化能无机自养古菌对远洋初级生产的实际贡献。此外，我建议在近环境条件下培养尚未表征的深海thaumarchaeota分支的成员，以获得他们的生理和遗传特征。总之，该研究项目旨在获得世界上最丰富的生物群之一的生物学新发现，并有助于对海洋碳循环的地球化学理解。