Collaborative Research: Evolution of Early Metabolism: Carbon Fixation, Anaerobic Respiration and ROS Detoxification in the Anaerobic Vent Bacterium, Thermovibrio ammonificans

合作研究：早期代谢的进化：厌氧排气细菌、氨化热弧菌的碳固定、无氧呼吸和ROS解毒

• 批准号: 1517560
• 负责人: Dionysios Foustoukos
• 金额: $ 19.46万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-15 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1517560&HistoricalAwards=false
• 关键词: Collaborative; Research; Evolution; Early; Metabolism

Bacteria that can live without oxygen (anaerobes) and survive in hot environments (thermophiles) inhabit extreme environments such as deep-sea hydrothermal vents that resemble the early Earth. These modern-day bacteria co-evolved with our planet, and as a result, these organisms carry both ancestral and more recently acquired genes and can be used as models to reconstruct the evolution of microbial processes, including how these bacteria obtained energy and the carbon needed to grow. To gain insight into these processes Thermovibrio ammonificans, an organism that inhabits deep-sea hydrothermal vents, will be studied. Integrated into these studies will be outreach activities for middle and high school students. Lesson plans will be developed and used in after-school programs, in professional training programs for K-12 educators, and informal activities such as the 4-H Summer Science Program. Anaerobic chemolithoautotrophic bacteria inhabiting deep-sea hydrothermal vents are critically important from an ecological standpoint; by fixing carbon dioxide of geothermal/magmatic origin in the absence of oxygen, they are the primary producers in these environments. This project will provide insight into the evolution of early and acquired bacterial metabolism by leveraging different types of culture approaches (batch and continuous cultures) with comparative genomic analyses of the model organism, Thermovibrio ammonificans. Experiments will address whether an early Earth ancestor of T. ammonificans was originally a hydrogen-oxidizing, sulfur-reducing bacterium that could form needed organic substances from simple inorganic substances (such as carbon dioxide). With the gradual rise of oxygen in the atmosphere, more efficient terminal electron acceptors became available and this bacterium acquired genes that increased its metabolic flexibility - e.g., the capacity to use nitrate as well as carbon dioxide - while retaining ancestral metabolic traits (such as the ability to live without oxygen and survive high temperatures). The mechanisms of carbon fixation, anaerobic respiration and detoxification of reactive oxygen species in T. ammonificans will be investigated using a combination of transcriptomic, proteomic and biomass carbon stable isotope analyses. This study will provide invaluable information on gene expression in T. ammonificans grown under chemical and nutrient conditions that reflect, as closely as possible, those encountered in its natural environment and will provide insight on gene regulation and expression in response to changing environmental conditions. This study is anticipated to help reconstruct the ancestral and acquired metabolic traits of this deep-branching organism and shed light into the emergence and evolution of autotrophic carbon fixation pathways.

可以在没有氧气的情况下生存并在炎热环境中生存的细菌（嗜热菌）栖息在极端环境中，例如类似于早期地球的深海热液喷口。 这些现代细菌与我们的星球共同进化，因此，这些生物体携带祖先和最近获得的基因，可以用作重建微生物过程进化的模型，包括这些细菌如何获得能量和碳需要成长。为了深入了解这些过程，将对氨热弧菌（一种栖息于深海热液喷口的生物体）进行研究。这些研究将纳入针对中学生和高中生的外展活动。 将制定课程计划并用于课后计划、K-12 教育工作者的专业培训计划以及 4-H 夏季科学计划等非正式活动。 从生态角度来看，栖息在深海热液喷口的厌氧化能自养细菌至关重要；通过在没有氧气的情况下固定地热/岩浆来源的二氧化碳，它们是这些环境中的主要生产者。该项目将通过利用不同类型的培养方法（分批和连续培养）以及对模型生物——氨化热弧菌（Thermovibrio ammonificans）进行比较基因组分析，深入了解早期和后天细菌代谢的演变。实验将探讨氨化氨菌的早期地球祖先是否最初是一种氧化氢、还原硫的细菌，可以从简单的无机物质（例如二氧化碳）形成所需的有机物质。随着大气中氧气的逐渐增加，更有效的末端电子受体变得可用，并且这种细菌获得了增加其代谢灵活性的基因，例如利用硝酸盐和二氧化碳的能力，同时保留了祖先的代谢特征（例如能够在没有氧气的情况下生存并在高温下生存）。将结合转录组学、蛋白质组学和生物质碳稳定同位素分析来研究 T. ammonificans 的碳固定、无氧呼吸和活性氧解毒机制。这项研究将提供关于在化学和营养条件下生长的氨化氨菌基因表达的宝贵信息，这些条件尽可能地反映其在自然环境中遇到的情况，并将提供有关响应不断变化的环境条件的基因调控和表达的见解。这项研究预计将有助于重建这种深分支生物的祖先和后天代谢特征，并揭示自养碳固定途径的出现和进化。