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

点击翻译按钮获取中文摘要

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.