Dimensions: The Role of Viruses in Structuring Biodiversity in Methanotrophic Marine Ecosystems

海洋甲烷营养生态系统每年消耗约75 Tg的甲烷，阻止这种强效温室气体进入大气。因此，这些微生物生态系统在全球气候系统中起着至关重要的作用。这些群落的性质取决于氧的存在或缺乏：甲烷化是好氧浅层沉积物中的一种细菌生活方式，但在较深的厌氧沉积物中，它是古细菌的专属领域，与硫酸盐还原细菌共同作用。已知哪些门在甲烷营养环境中最常见。然而，由于这些环境在物理上难以接近，而且几乎所有来自这些系统的微生物都抵制培养，对这些群落的理解远远落后于它们的重要性。这些系统中微生物宿主的培养抗性也阻碍了传统方法研究病毒群落的使用。因此，迄今为止，科学在很大程度上无法填补海洋甲烷营养生物多样性的大致轮廓，无法充分描述微生物群落或确定它们的形成原因。本项目旨在确定病毒在甲烷营养海洋生态系统结构、功能、遗传和分类多样性中的重要性。潜在的主张是，病毒通过导致死亡和水平基因转移来构建这些生态系统中古细菌和细菌群落的多样性。为了确定病毒对好氧和厌氧海洋甲烷营养生态系统生物多样性的贡献，该项目在野外和实验室环境中结合了生物地球化学、基因组学和宏基因组学方法。该项目首先寻求通过扩展已建立的稳定同位素探测技术来量化海底甲烷渗漏的病毒产生率，从而评估病毒的原位活性。同样的技术将被用于追踪碳从甲烷到微生物再到病毒的流动，并从那些积极循环甲烷衍生碳的生物体中分离遗传物质，从而使微生物和病毒宏基因组的生产成为可能，这些宏基因组锚定在生态系统功能中。这些宏基因组之间的比较将揭示生物之间传递的任何功能序列，为评估功能多样性和遗传多样性之间的关系提供基础。同时，单细胞全基因组扩增将精确定位单个细胞，以便与微生物和病毒组合进行比较，从而评估分类学和遗传多样性之间的关系。最后，通过比较不同海洋甲烷营养生态系统内部和之间的基因组和宏基因组数据，可以分析功能多样性和分类多样性之间的关系。更广泛的影响该项目将为博士后研究人员、研究生和本科生提供培训。一个实地考察课程将带领约12名本科生进行研究考察，为他们提供丰富的教育经验，真正实现教学与研究的结合。为了促进将这项研究转化为公共领域，将发展和主持一个关于科学传播的讲习班，由一位资深科学记者领导。PI将继续以身作则，带头开展外联工作，为记者、联邦机构和国会议员提供资源。

Marine methanotrophic ecosystems are responsible for consuming around 75 Tg of methane annually, preventing this potent greenhouse gas from entering the atmosphere. These microbial ecosystems thus play a vital role in the global climate system. The nature of these communities depends on the presence or absence of oxygen: methanotrophy is a bacterial lifestyle in aerobic shallow sediments, but in deeper anaerobic sediments it is the exclusive province of archaea, in syntrophy with sulfate-reducing bacteria. It is known which phyla are most commonly found in methanotrophic environments. However, because of these environments' physical inaccessibility and because nearly all microbes from these systems have resisted cultivation, understanding of these communities lags far behind their importance. The cultivation-resistance of microbial hosts from these systems has additionally prevented the use of classical methods to study the viral community. Thus, to date science is largely unable to fill in the broad outlines of marine methanotrophic biodiversity, to fully describe the microbial communities or determine what shapes them.This project seeks to define the importance of viruses in structuring functional, genetic, and taxonomic diversity in methanotrophic marine ecosystems. The underlying assertion is that viruses structure the diversity of archaeal and bacterial communities in these ecosystems by causing both mortality and horizontal gene transfer. To establish viral contributions to biodiversity of aerobic and anaerobic marine methanotrophic ecosystems, this project combines biogeochemical, genomic, and metagenomic approaches, in both field and laboratory settings.IntegrationThe project first seeks to assess viral activity in situ by extending established stable isotope probing techniques to quantify rates of viral production at sea floor methane seeps. The same techniques will be used to track the flow of carbon from methane to microbes to viruses and to isolate genetic material from just those organisms that actively cycle methane-derived carbon, enabling the production of microbial and viral metagenomes that are anchored in ecosystem function. Comparisons among these metagenomes will reveal any functional sequences in transit between organisms, providing the basis for an evaluation of the relationships between functional and genetic diversity. At the same time, single-cell whole-genome amplification will pinpoint individual cells for comparison with the microbial and viral assemblages, permitting assessment of the relationships between taxonomic and genetic diversity. Last, the comparison of genomic and metagenomic data both within and across distinctive marine methanotrophic ecosystems will enable analysis of the relationship between functional and taxonomic diversity.Broader impactsThe project will offer training to postdoctoral researchers and graduate and undergraduate students. A field studies course will bring ~12 undergraduates on a research expedition and provide them a rich educational experience, truly integrating teaching and research. To facilitate translation of this research to the public sphere, a workshop on science communication will be developed and hosted, led by a veteran science journalist. The PI will continue to lead outreach efforts by example, serving as a resource to journalists, federal agencies, and members of Congress.