Diversity of autotrophic organisms and their carbon fixation pathways at hydrothermal vent systems on the Arctic Mid-Ocean Ridge

将二氧化碳固定在生物质中可以说是最基本的生物过程，也是地球上生命的先决条件。虽然光合作用生物通过还原的戊糖磷酸循环固定全球碳的大部分，但海洋热液喷口系统作为基于阳光不依赖于阳光的原核生物碳固定的生命热点受到了研究的关注。热液喷口不同无机能量底物的陡峭梯度为各种自养生物创造了生态位。在过去的几年里，从热液地点恢复了大量的基因组数据，并发现了意想不到的微生物多样性，但由于从热液喷口采样和培养微生物的困难，有关代谢和活性的功能数据仍然稀缺。这种差异阻碍了对基因组数据的详尽解释，并限制了描述这些生态系统并评估它们在全球碳循环中的作用的代谢模型的准确性。在这里，我提议对北冰洋中脊(AMOR)沿线最近发现的热液喷口区域的微生物初级生产者及其代谢策略进行深入研究，我将与我的东道主Ida Steen教授合作开展这项研究，Ida Steen教授是挪威卑尔根大学K.G.杰布森深海研究中心的小组负责人。我将对阿莫尔号上不同的喷口位置进行差异化采样、模拟自然条件的船上培养、稳定同位素探测、元基因组学和详细的生物信息学分析，以确定自养生物及其固碳途径，并评估它们对初级生产的贡献。这种多角度的研究方法，结合功能和组学数据，使我能够得出结论，影响不同的固碳途径在自然界的分布，以及它们如何适应不同的生态位。此外，它使我能够寻找新的和意想不到的碳固定策略。这项研究将有助于正在进行的努力，以建立海洋热液遗址作为模式系统，这是朝着从酶到生态系统的海洋热液喷口系统自养碳固定的全面图景迈出的一步。

The fixation of carbon dioxide into biomass is arguably the most fundamental biological process, and a prerequisite for life on earth. While photosynthetic organisms account for the majority of global carbon fixation via the reductive pentose phosphate cycle, marine hydrothermal vent systems have gained research attention as hot spots for life based on sunlight-independent prokaryotic carbon fixation. The steep gradients of different inorganic energy substrates at hydrothermal vents create ecological niches for diverse autotrophic organisms.An abundance of genomic data has been recovered from hydrothermal sites and uncovered an unexpected microbial diversity over the last years, but functional data regarding metabolism and activity is still scarce due to difficult sampling and culturing of microorganisms from hydrothermal vents. This discrepancy prevents an exhaustive interpretation of genomic data and limits the accuracy of metabolic models that describe these ecosystems and assess their role in the global carbon cycle. Here I propose an in-depth study of the microbial primary producers and their metabolic strategies at recently discovered hydrothermal vent fields along Arctic Mid-Ocean Ridge (AMOR), which I will carry out in cooperation with my host Prof. Ida Steen, who is a group leader at the K. G. Jebsen Centre for Deep Sea Research at the University of Bergen in Norway. I will carry out differentiated sampling of different vent sites on the AMOR, shipboard incubations simulating natural conditions, stable isotope probing, metagenomics and a detailled bioinformatic analysis in order to identify autotrophic organisms and their carbon fixation pathways, and to estimate their contribution towards primary production.This multi-angled research approach, integrating functional with omics data, allows me to draw conclusions about the factors that influence the distribution of different carbon fixation pathways in nature, and about how they are adapted to diverse ecological niches. Additionaly, it enables me to search for novel and unexpected carbon fixation strategies. This study will contribute to the ongoing efforts to establish the hydrothermal sites on the AMOR as model systems, and it is a step towards a comprehensive picture of autotrophic carbon fixation at marine hydrothermal vent systems, from enzymes to ecosystems.