Microbial activity in the crustal deep biosphere

海洋深层生物圈是海底生物的栖息地。该地区的能源来源非常少，这就产生了一个关于生命如何在那里持续存在的悖论。解决这一能源悖论是深层生物圈研究中的一项重大挑战。美国华盛顿海岸外的胡安德富卡山脊是一个交通便利、低能耗的环境，这使它成为应对这一挑战的一个有吸引力的地点。将在Juan de Fuca海脊侧翼的海底进行一系列实验，利用已建立的进入地壳深层生物圈的海底观测站，首次直接就地测量地壳次表层的微生物活动。这个项目将提供有关生命在我们无法在实验室复制的条件下生存的能力的基本信息，但这些信息对于了解环境中微生物群落的相互作用越来越重要。然后，这些信息可用于全球微生物活动模型，以估计这一生物圈对元素循环的影响，改变我们对这一巨大海底栖息地内微生物过程的理解。为了将这些发现传达给公众，该项目将在邮轮期间包括一个船到岸的拓展计划。此外，还将举办公开讲座，并为在缅因州毕格罗海洋科学实验室举行的年度公众开放日设立深海视频片段的互动展示。将招募不同的本科生和一名博士后研究人员参加研究和公共宣传活动。该项目提议利用胡安德富卡山脊东侧现有的地下基础设施，在单细胞分子和地球化学方法方面取得进展，以对地壳深层生物圈中的生命活动作出根本性的新发现。在为期两周的研究巡航期间，研究小组将在现场和实验室中用标记的底物培养地壳流体，以跟踪单细胞活动，并结合放射性同位素示踪剂活动和恒电位仪测量，目的是确定现场和潜在的活动速率和细胞生理学。这项研究还将确定活性微生物在原位和实验室条件下利用哪些代谢，这些过程的速率，以及涉及的微生物。预计这些结果将对微生物活动和来自地壳深层生物圈的原位微生物生长率提供明确的假设检验，以改变对地壳深层生物圈微生物活动的理解，并产生关于生命在低能量条件下生存的能力的关键信息。

The marine deep biosphere is the habitat for life existing under the sea floor. The zone has remarkably low energy sources creating a paradox of how life can persist there. Resolving this energy paradox is a grand challenge in deep biosphere research. The Juan de Fuca Ridge flank off the coast of Washington, USA, is an accessible, low energy environment making it an attractive location for addressing this challenge. A series of experiments will be conducted on the seafloor at the Juan de Fuca Ridge flank, using established subseafloor observatories that access the crustal deep biosphere, to provide the first direct in situ measurement of microbial activity in the crustal subsurface. This project will provide essential information about the ability of life to survive under conditions that we are not able to replicate in the laboratory, but that are increasingly important for understanding microbial community interaction in the environment. This information can then be used in models of global microbial activity for estimating the impact of this biosphere on elemental cycling, transforming our understanding of microbial processes within this vast subseafloor habitat. To communicate these discoveries to the public, the project will include a ship-to-shore outreach program during the cruise. In addition public lectures will be presented, and an interactive display of deep-sea video footage will be set up for the annual public Open House at the Bigelow Laboratory for Ocean Sciences in Maine. Diverse undergraduate students and a postdoctoral researcher will be recruited to participate in the research and public outreach activities.This project proposes to leverage existing subsurface infrastructure on the eastern flank of the Juan de Fuca Ridge with advances in single-cell based molecular and geochemical approaches to make fundamental new discoveries about the activity of life in the deep crustal biosphere. During a two-week research cruise, the research team will incubate crustal fluids in situ and in the laboratory with labeled substrates for tracking single-cell activity, coupled with radioisotope tracer activity and potentiostat measurements, with the objective of determining in situ and potential rates of activity and cellular physiology. The research will also identify which metabolisms active microorganisms utilize under in situ and laboratory conditions, the rates of these processes, and the microorganisms involved. The results are expected to provide explicit hypothesis testing of microbial activity and in situ microbial growth rates from the crustal deep biosphere to transform understanding of microbial activity in the crustal deep biosphere and generate critical information about the ability of life to survive under low energy conditions.