Linking microbial community composition, metabolic functions and ecology in terrestrial subsurface and surface habitats

陆地地下位于我们脚下，在大陆和岛屿的大陆上。这些地下栖息地包含地球上的大部分微生物，它们参与碳、氮或磷等关键元素的循环和储存，特别是在含水层生态系统中。这些含水层提供了我们大部分的饮用水，由流经饱和和非饱和岩层的地下水组成。因此，地下微生物既可以在水中以自由生活的浮游状态存在，也可以以固着状态附着在固体表面上。了解地下发生的基本生物地球化学过程是基于对居住在这些环境中的微生物种群的群落组成和活动的调查。由于含水层是由从地表渗出的水维持的，它们与地表表现出不同程度的连通性，容易受到地表条件变化的影响。然而，地表和地下微生物生态之间的联系很少被提及，这将是本研究计划的中心轴。这项研究计划的长期目标是通过将地下环境作为与表层水生生态系统有联系的开放系统来研究，从而了解地下环境的微生物生态和功能。短期目标是：1)确定在地表补给区、地下水和地表排泄区之间形成的浮游微生物群落组成和相关功能能力的演替；2)确定地下水浮游生物群落的组成和代谢活动以及影响这种微生物活动的环境因素；3)确定生活在岩石表面的微生物群落的组成、丰度和代谢特征。为了实现这些目标，我们将在魁北克的三个不同含水层系统的基础上，应用最先进的组学和基于文化的方法相结合。这些尖端方法的应用，以及与其他研究人员的合作(例如，研究水生生境、水文地质学家)，将能够培养出高素质的研究生。拟议的研究将扩大我们关于地下含水层系统中微生物的来源以及这些微生物在地下遇到的具有挑战性的波动条件下生存所利用的代谢活动的知识。我们将地下作为一个开放系统进行研究的独创方法，将提供对地下微生物种群难以捉摸的总体构成的关键见解。这种方法将使致力于地表和地下微生物生态的研究人员聚集在一起。这些发现将对预测这些栖息地对地表扰动的反应至关重要。

The terrestrial subsurface lies beneath our feet in the landmasses of continents and islands. These underground habitats contain a major portion of the microorganisms on Earth, who participate in the cycling and storage of key elements such as carbon, nitrogen or phosphorus, particularly in aquifer ecosystems. These aquifers, which provide most of our drinking water, are composed of groundwater flowing through layers of saturated and unsaturated rocks. Thus, subsurface microorganisms can be found either in a free-living planktonic state in the water, or in a sessile state attached to solid surfaces. Understanding the essential biogeochemical processes occurring in the subsurface is based on investigations of community composition and activities of microbial populations inhabiting these environments. Because aquifers are sustained by water seeping from the surface, they show various degrees of connectivity to the surface and are vulnerable to changes in surface conditions. However, links between surface and subsurface microbial ecology have rarely been addressed, and will be a central axis in this research program. The long-term objective of this research program is to understand the microbial ecology and functioning of subsurface environments by studying them as open systems with links to and from surface aquatic ecosystems. The short-term objectives are to 1) establish the succession in planktonic microbial community composition and associated functional capacities that develop between surface recharge areas, subsurface groundwaters, and surface discharge regions; 2) determine the composition and metabolic activities of the groundwater planktonic communities and the environmental factors influencing this microbial activity; and 3) identify the composition, abundance and metabolic characteristics of the microbiota living on rock surfaces. To address these objectives, we will apply a combination of state-of-the-art omics and culture-based approaches, based on three distinct aquifer systems in Quebec. Application of these cutting-edge methods, and collaborations with other researchers (e.g. working on aquatic habitats, hydrogeologists), will allow training of highly qualified graduate students. The proposed research will expand our knowledge on the origin of microorganisms in subsurface aquifer systems, and on the metabolic activities employed by these microbes to survive in the challenging fluctuating conditions encountered in the subsurface. Our original approach of studying the subsurface as an open system will provide key insights into the elusive overall composition of subsurface microbial populations. This approach will allow bringing together researchers working on surface and subsurface microbial ecology. These findings will be crucial in predicting responses of these habitats to surface perturbations.