Collaborative Research: Influence of pressure on microbial communities in subseafloor sediment at hadal, abyssal, bathyal, and shelf water depths

横跨全球的海底沉积物领域是地球上探索最少的大型生物群落。该项目解决了一个关于海底沉积环境中微生物群落的基本问题——它们在多大程度上、以何种方式适应了它们所在的低温高压环境？或者，它们只是偶然从较浅、气压较低的世界被引入，而这些世界是它们的主要来源？这个项目正在研究这些生物如何代谢沉积物中的有机物。该项目还推动了科学、技术、工程和数学（STEM）领域多样化、具有全球竞争力的劳动力队伍的发展。它通过将10名或更多的学生纳入船上科学家的行列，向他们介绍海上研究。该项目特别侧重于为STEM领域中代表性不足的少数群体学生、经济背景不利的学生、波多黎各学生以及不同教育阶段（从社区大学到研究生院）的学生创造和资助机会，这些学生对STEM有不同的兴趣。研究来自探险的样本和数据是这些多个机构的学生研究生和本科生研究的核心。该项目还为更广泛的科学界提供支持，通过收集和提供不同的样本进行其他研究，包括但不限于研究深海沟渠中的深水停留时间、过去的海洋条件和海底微生物。该项目的基本目标是确定海底微生物群落和活动是如何跨越海洋深度带（沿海下、深海、深海、浅海）的梯度受到周围水压力的影响的。正在测试的主要假设是“海底沉积物中的微生物群落适应了原位压力。”零假设是，这些“群落只是从较浅的深度引入的残余种群，对原位压力的适应能力较差。”为了验证这些假设，该项目比较了波多黎各海沟地区海平面以下50至~8400米海洋深处缺氧海底沉积物中的海底群落和活动速率。为了收集样品和船上数据，该项目包括一个26天的取心程序。该项目调查了整个海洋深度范围内海底沉积群落的基因组组成和群落代谢率。正在进行实验，以确定潜在过程（硫酸盐还原和甲烷生成）的压力依赖性，以及海底下、深海、深海和深海海底群落在原位压力下优先表达的基因。将这些结果综合起来，以确定海底群落对原位压力的适应性质和程度。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The globe-spanning realm of subseafloor sediment is Earth’s least-explored large biome. This project addresses a fundamental question about the microbial communities that inhabit the subseafloor sedimentary environment – to what extent and in what ways are they adapted to the low temperature, high pressure conditions where they are found? Or, alternatively, are they just accidentally introduced from the shallower and lower-pressure world where the organic matter that feeds them largely originates? This project is examining how these organisms metabolize organic matter in sediments. The project is also advancing the development of a diverse, globally competitive workforce in science, technology, engineering, and mathematics (STEM). It introduces 10 or more students to sea-going research, by including them as shipboard scientists. The project especially focusses on creating and funding opportunities for students from minority groups under-represented in STEM fields, students from economically disadvantaged backgrounds, and students from Puerto Rico, and from multiple educational stages (ranging from community college to graduate school), with diverse STEM interests. Study of samples and data from the expedition are central to graduate and undergraduate research by students from these multiple institutions. The project also supports the broader science community by collecting and providing diverse samples for additional studies, including, but not limited to, studies of deep-water residence time in a deep-sea trench, past oceanographic conditions, and subseafloor microbes. The fundamental objective of this project is to determine how the subseafloor microbial communities and activities across a gradient of oceanic depth zones (sublittoral, bathyal, abyssal, hadal) are impacted by the pressure of the surrounding water. The primary hypothesis being tested is that “microbial communities in subseafloor sediment are adapted for in situ pressure.” The null hypothesis is that these “communities are merely remnant populations introduced from shallower depths and poorly adapted for in situ pressure.” To test these hypotheses, the project compares the subseafloor communities and rates of activity that occur in anoxic subseafloor sediment at ocean depths ranging from 50 to ~8400 meters below sea level in the Puerto Rico Trench region. To collect the samples and shipboard data, the project includes a 26-day coring program. The project interrogates the genomic composition and community metabolic rates of the subseafloor sedimentary communities over this full range of ocean depths. Experiments are being conducted to determine the pressure-dependence of potential processes (sulfate reduction and methanogenesis) and genes that are preferentially expressed at in situ pressures by sublittoral, bathyal, abyssal and hadal subseafloor communities. These results are synthesized to identify the nature and extent of adaptations to in situ pressure in subseafloor communities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.