LExEn: Water Stress Dynamics in Anhydrophilic Microbial Mats: Assessing the Limit of Planetary Life

生命存在和繁衍的最基本标准是水的存在。极端微生物（嗜热菌、嗜热菌、嗜压菌、嗜酸菌、嗜盐菌、嗜碱菌）可以在环境中定居并活跃生长，尽管环境恶劣，但只要水充足。相比之下，无水植物对间歇性暴露于液相或气相水以及细胞组分缺乏水的单层覆盖的长期水胁迫表现出高耐受性。在这些条件下，电池也可能受到极端温度、太阳辐射和高盐度的影响。现存的远古生物对急性干燥的生存和恢复反应可能提供了理解其他行星和卫星上生命过程的关键控制的关键信息，这些行星和卫星可能存在各种形式的水（即火星和欧罗巴）。这项研究将调查和表征微生物垫的能力，这些微生物垫被认为是地球上第一个现存生物群落的现代类似物，以干燥的形式在水胁迫下生存。微生物垫在陆地和水生生态系统中普遍存在，自我维持，并且通常是地球上一些最极端（即温度，辐照度，营养耗尽）环境中唯一功能性的生物群落。使用跨学科（生态学，生理学，分子生物学）和协作团队的方法，我们将确定水的可用性和水赤字如何决定垫社区在极端环境中的分布，活动和结构受到全球气候梯度，从极地到温带到热带倾斜。这项研究的结果将适用于生态、分子和地球化学研究，旨在了解在缺水条件下基于发展、生存和进化的行星生命的极限。

The most fundamental criterion for the existence and proliferation of life is the presence of water. Extremophiles (thermophiles, pychrophiles, barophiles, acidophiles, halophiles, alkalphiles) can colonize and grow actively in environments, albeit harsh ones, as long as water is abundant. In contrast, anhydrophiles, exhibit a high tolerance for both intermittent exposure to liquid or gas-phase-water, and long term water stress where cellular components lack a monolayer coverage of water. Under these conditions cells may also be subjected to extremes of temperature, solar irradiation, and hypersalinity. The survival and recovery responses of extant anhydrophiles to acute desiccation may provides information critical to understanding key controls of life processes on other planets and moons where various forms of water may exist (i.e. Mars and Europa). This study will investigate and characterize the ability of microbial mats, which are believed to be modern day analogs of Earth's first extant biotic communities, to survive water stress in the form of desiccation. Microbial mats are ubiquitous, self-sustaining, features in terrestrial and aquatic ecosystems and are often the only functional biotic communities in some of the most extreme (i.e. temperature, irradiance, nutrient deplete) environments on Earth. Using an interdisciplinary (ecology, physiology, molecular biology) and collaborative team approach, we will determine how water availability and water deficit determine the distribution, activities and structure of mat communities in extreme environments subject to a global climatic gradient, ranging from polar to temperate to tropical clines. The results from this research will be applicable to ecological, molecular and biogeochemical studies aimed at understanding the limit of planetary life based on development, survival and evolution under water-deprived conditions.