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

将二氧化碳固定到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。虽然光合生物通过还原性磷酸戊糖循环占全球固碳的大部分，但海洋热液喷口系统作为基于不依赖阳光的原核固碳的生命热点已获得研究关注。热液喷口不同无机能源基质的陡峭梯度为不同的自养生物创造了生态位，在过去几年里，从热液喷口回收了丰富的基因组数据，并发现了意想不到的微生物多样性，但由于难以从热液喷口取样和培养微生物，有关代谢和活动的功能数据仍然很少。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其在全球碳循环中作用的代谢模型的准确性。在这里，我建议深入研究微生物初级生产者和他们的代谢策略，在最近发现的热液喷口领域沿着北极大洋中脊（AMOR），我将与我的东道主Ida Steen教授合作，他是K. G.挪威卑尔根大学的捷成深海研究中心。我将通过对AMOR不同喷口点的差异化采样、模拟自然条件的船上培养、稳定同位素探测、宏基因组学和详细的生物信息学分析，识别自养生物及其固碳途径，并估算其对初级生产的贡献。这种多角度的研究方法，将功能与组学数据相结合，让我得出结论的因素，影响不同的碳固定途径在自然界中的分布，以及它们是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。这项研究将有助于目前为建立AMOR上的热液地点作为模型系统所作的努力，也是朝着全面了解海洋热液喷口系统从酶到生态系统的自养固碳情况迈出的一步。

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.