PNNL

Abstract

Microbial communities in aquifers consist of diverse interactive individuals that break down complex organic matter for metabolic energy. Microbes are adapted to function over a large range in environmental conditions, ranging from freezing to boiling acidic to alkaline. They can use oxygen as a reducible metabolite during organic carbon oxidation, but, since oxygen is rapidly depleted in subsurface environments, different groups of organisms may also rely on other compounds such as reducible metals, or on fermentation. Community members are interdependent, but compete for resources, and communities often have predominant groups that rely on recognizable chemical pathways, such as sulfate reduction. The predominant group varies spatially and temporally as the available nutrients change or are depleted.