About this Research Topic
The deep subsurface biosphere refers to the vast ecosystems of microorganisms that exist within marine subseafloor sediments and the oceanic crust, as well as continental subterranean environments. They are estimated to contain a significant portion of the total biomass on Earth and are comprised of diverse microbial taxa including bacteria, archaea, protists, and fungi that survive in environments that are often extremely energy-limited. Due to the unique characteristics of these ecosystems, deep subsurface microorganisms are often distinct from those found in surface environments and laboratory strains. They are becoming a crucial topic of research for their unusual adaptations to energy limitation and their important interactions with the geosphere.
Despite its size and significance, however, the deep biosphere remains largely understudied. One of the main gaps in our knowledge is the extent of microbial biogeochemical activity across the physicochemical gradients that characterize deep biosphere extreme ecosystems. This is due, in large part, to the high uncertainty in metabolic rate estimates and unknown systematic biases due to data scarcity. Bioenergetic studies have provided a conceptual framework for understanding the complexity of microbial metabolism within various spatial and temporal scales. However, our knowledge of energy metabolism in the deep biosphere is hindered by inadequate methodology for energy flux quantification and incomplete data of the actual energy parameters associated with subsurface microbes, many of which are novel and uncharacterized species. Despite these gaps, research on the deep biosphere continues to provide new insights into the function of these unique microbial communities and their potential to reach and impact the chemical economy of the overlying ecosystems.
The aim of this Research Topic is to open a new perspective on the biotic/abiotic interface in extreme microbiology. We invite contributions from scientists working in diverse disciplines who have a common interest in various aspects of the study of microorganisms that live in energy-limited deep subsurface environments. This can include research on the diversity, activity, genetic repertoire, and expression of subsurface microbial communities and their resulting biogeochemical activity. We encourage the submission of manuscripts focusing on recent advances in deep biosphere studies by using both empirical and theoretical approaches.
Articles in this Research Topic are dedicated to commemorating the late Jan Amend, whose pioneering work significantly advanced our understanding of microbial life in deep subsurface environments. Amend's contributions not only challenged existing notions about the limits of life but also provided key insights into the survival strategies of microbes in energy-limited settings, continuing to inspire and guide current research in extreme microbiology.
Keywords: biosphere, microbiology, biogeochemistry, extremophiles, subsurface, metabolism
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.