Collaborative Research: Microbial hydrogen oxidation at high pressure: Role of hydrogenases and interspecies hydrogen transfer

地球微生物生物圈的很大一部分生活在深海和洋壳以下，处于高静水压力条件下。然而，关于这些适应高压的微生物群落对地球微生物群的贡献、它们在生物地球化学循环中的作用以及它们与地球早期生命进化的相关性，人们知之甚少。本项目将研究以氢为能源的高压和高温细菌对不同压力和氢浓度制度的适应机制。将使用一种用于高压和高温下细菌培养的创新仪器来模拟深海的物理(温度、压力)和化学(氢浓度)条件。这种实验方法提供了一个独特的机会，通过动态调整压力条件来研究微生物的活动和功能。还将监测在不同压力和温度下的基因表达。最后，由于氢氧化被认为是一种古老的代谢途径，了解这些生物中的氢分解代谢可能有助于重建早期新陈代谢的进化史。研究人员将为初中和高中年龄的学习者开发课程和活动来翻译科学。作为研究生级别研讨会系列的一部分，乔治梅森大学和罗格斯大学将向本科生/研究生提供讲座和实验室演示/参观。以培养为基础的高压适应细菌的生理和代谢适应研究对于增进对深海生态系统中微生物活动和生物能量适应战略的理解至关重要。本研究的主要目的是探索从深海热液喷口分离的高压高温适应细菌(嗜热菌)的生理和基因表达。其中一种细菌，鹦鹉螺菌株PV-1，在高压和55摄氏度的温度下茁壮成长，可以依靠氢气和二氧化碳生存。旨在测量基因和蛋白质表达的实验将与稳定的氢同位素组成的测量相结合，以了解压力和氢浓度对嗜热菌生长的综合影响。更具体地说，该项目将研究菌株PV-1在400大气压以下的压力以及氢的限制和非限制浓度下不同氢酶的表达。此外，该项目将研究压力升高如何影响菌株PV-1的膜结构，这对保持细胞完整性和促进膜运输非常重要。最后，该项目将调查从产氢细菌Marinitoga Piezophila和消耗氢气的鹦鹉螺菌株PV-1转移氢气的情况。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

A large fraction of Earth’s microbial biosphere lives in the deep ocean and below the oceanic crust, under conditions of high hydrostatic pressures. However, very little is known about the contribution of these high-pressure adapted microbial communities to the Earth’s microbiome, their role in biogeochemical cycles, and their relevance for the evolution of early life on Earth. This project will investigate the adaptation mechanisms of high-pressure and high-temperature bacteria that use hydrogen as an energy source to different pressures and hydrogen concentration regimes. An innovative instrument for bacterial cultures at high pressure and temperature will be used to simulate the deep-sea physical (temperature, pressure) and chemical (hydrogen concentration) conditions. This experimental approach provides a unique opportunity to study microbial activity and functions by adjusting pressure conditions dynamically. Gene expression under different pressures and temperatures will also be monitored. Finally, since hydrogen oxidation is considered an ancient metabolic pathway, understanding hydrogen catabolism in these organisms may help to reconstruct the evolutionary history of early metabolism. The researchers will develop lessons and activities to translate the science for middle and high school aged learners. Lectures and lab demonstrations/tours will be delivered at George Mason University and Rutgers University to undergraduate/graduate students as part of graduate-level seminar series.Culture-based studies of the physiological and metabolic adaptations of high-pressure adapted bacteria are critical to advance understanding of microbial activity and bioenergetic adaptation strategies in deep-sea ecosystems. The main objective of this study is to explore the physiology and gene expression in high-pressure and high-temperature adapted bacteria (thermopiezophiles) that have been isolated from deep-sea hydrothermal vents. One of these bacteria, Nautilia strain PV-1, thrives at elevated pressure and at a temperature of 55°C, and can live off hydrogen gas and carbon dioxide. Experiments aimed at measuring gene and protein expression will be integrated with measurements of stable hydrogen isotope compositions to understand the combined effects of pressure and hydrogen concentration of the growth of thermopiezophiles. More specifically, this project will investigate the expression of the different hydrogenases of strain PV-1 in response to pressures up to 400 atmospheres, and to limiting and non-limiting concentration of hydrogen. Further, this project will investigate how elevated pressures affect the membrane structure of strain PV-1, which is important to maintain cellular integrity and to facilitate membrane trafficking. Finally, this project will investigate the transfer of hydrogen gas from a hydrogen-producing bacterium, Marinitoga piezophila, and the hydrogen consuming Nautilia strain PV-1.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.