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

陆地地下位于我们脚下的大陆和岛屿上。这些地下栖息地包含地球上大部分微生物，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。这些含水层为我们提供了大部分饮用水，由流经饱和和不饱和岩石层的地下水组成。因此，地下微生物可以在水中以自由生活的浮游状态存在，或者以附着在固体表面上的固着状态存在。了解地下发生的基本生物地球化学过程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，因此它们与地表表现出不同程度的连通性，并且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学之间的联系很少得到解决，并将成为该研究计划的中心轴。该研究计划的长期目标是通过将地下环境作为与地表水生生态系统相互联系的开放系统进行研究，以了解地下环境的微生物生态和功能。短期目标是 1) 建立浮游微生物群落组成的连续性以及在地表补给区、地下地下水和地表排放区之间发展的相关功能能力； 2）确定地下水浮游群落的组成和代谢活动以及影响该微生物活动的环境因素； 3) 确定岩石表面微生物群的组成、丰度和代谢特征。为了实现这些目标，我们将根据魁北克省三个不同的含水层系统，结合最先进的组学和基于文化的方法。这些尖端方法的应用以及与其他研究人员的合作（例如水生栖息地、水文地质学家）将能够培养高素质的研究生。拟议的研究将扩大我们对地下含水层系统微生物起源的了解，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采用的代谢活动。我们最初将地下作为一个开放系统进行研究的方法将为了解地下微生物种群难以捉摸的整体组成提供重要的见解。这种方法将使研究地表和地下微生物生态学的研究人员聚集在一起。这些发现对于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.