Microbial Life Of The Deep Biosphere

Over the last two decades, exploration of the deep subsurface biosphere has developed into a major research area. New findings constantly challenge our concepts of global biogeochemical cycles and the ultimate limits to life. In order to explain our observations from deep subsurface ecosystems it is necessary to develop truly interdisciplinary approaches, ranging from microbiology and geochemistry to physics and modeling. This book aims to bring together a wide variety of topics, covering the broad range of issues that are associated with deep biosphere exploration. Not only does the book present case studies of selected projects, but also treats questions arising from our current knowledge. Despite nearly two decades of research, there are still many boundaries to exploration caused by technical limitations and one section of the book is devoted to these technical challenges and the latest developments in this field. This volume will be of high interest to biologists, chemists and earth scientists all working on the deep biosphere.

Deep biosphere research is at the scientific frontier of bio- and geo-related sciences, yet it is largely underexplored. In terms of volume, deep subsurface settings represent some of the largest microbial habitats on the planet, and the combined biomass of the deep biosphere encompasses the largest living reservoir of carbon, excluding land plants. However, the paleo-record of the deep biosphere is still largely uncharted and neglected. The aim of this book is to highlight current research on deep life through time and bring together researchers with various perspectives. The book presents a collection of scientific contributions that provide a sample of forefront research in this field. The contributions involve a range of case studies of deep ancient life in continental and oceanic settings, of microbial diversity in sub-seafloor environments, and of the isolation of calcifying bacteria, as well as reviews on clay mineralization of fungal biofilms and on the carbon isotope records of the deep biosphere. Deciphering the fossil record of the deep biosphere is a challenging task but, when successful, will unlock doors to life’s cryptic past.

This book sets forth a set of truly controversial and astonishing theories: First, it proposes that below the surface of the earth is a biosphere of greater mass and volume than the biosphere the total sum of living things on our planet's continents and in its oceans. Second, it proposes that the inhabitants of this subterranean biosphere are not plants or animals as we know them, but heat-loving bacteria that survive on a diet consisting solely of hydrocarbons that is, natural gas and petroleum. And third and perhaps most heretically, the book advances the stunning idea that most hydrocarbons on Earth are not the byproduct of biological debris ("fossil fuels"), but were a common constituent of the materials from which the earth itself was formed some 4.5 billion years ago. The implications are astounding. The theory proposes answers to often-asked questions: Is the deep hot biosphere where life originated, and do Mars and other seemingly barren planets contain deep biospheres? Even more provocatively, is it possible that there is an enormous store of hydrocarbons upwelling from deep within the earth that can provide us with abundant supplies of gas and petroleum? However far-fetched these ideas seem, they are supported by a growing body of evidence, and by the indisputable stature and seriousness Gold brings to any scientific debate. In this book we see a brilliant and boldly original thinker, increasingly a rarity in modern science, as he develops potentially revolutionary ideas about how our world works.

Deep subsurface microbiology is a highly active and rapidly advancing research field at the interface of microbiology and the geosciences; it focuses on the detection, identification, quantification, cultivation and activity measurements of bacteria, archaea and eukaryotes that permeate the subsurface biosphere of deep marine sediments and the basaltic ocean and continental crust. The deep subsurface biosphere abounds with uncultured, only recently discovered and – at best - incompletely understood microbial populations. In spatial extent and volume, Earth's subsurface biosphere is only rivaled by the deep sea water column. So far, no deep subsurface sediment has been found that is entirely devoid of microbial life; microbial cells and DNA remain detectable at sediment depths of more than 1 km; microbial life permeates deeply buried hydrocarbon reservoirs, and is also found several kilometers down in continental crust aquifers. Severe energy limitation, either as electron acceptor or donor shortage, and scarcity of microbially degradable organic carbon sources are among the evolutionary pressures that have shaped the genomic and physiological repertoire of the deep subsurface biosphere. Its biogeochemical role as long-term organic carbon repository, inorganic electron and energy source, and subduction recycling engine continues to be explored by current research at the interface of microbiology, geochemistry and biosphere/geosphere evolution. This Research Topic addresses some of the central research questions about deep subsurface microbiology and biogeochemistry: phylogenetic and physiological microbial diversity in the deep subsurface; microbial activity and survival strategies in severely energy-limited subsurface habitats; microbial activity as reflected in process rates and gene expression patterns; biogeographic isolation and connectivity in deep subsurface microbial communities; the ecological standing of subsurface biospheres in comparison to the surface biosphere – an independently flourishing biosphere, or mere survivors that tolerate burial (along with organic carbon compounds), or a combination of both? Advancing these questions on Earth’s deep subsurface biosphere redefines the habitat range, environmental tolerance, activity and diversity of microbial life.

This volume summarizes recent advances in environmental microbiology by providing fascinating insights into the diversity of microbial life that exists on our planet. The first two chapters present theoretical perspectives that help to consolidate our understanding of evolution as an adaptive process by which the niche and habitat of each species develop in a manner that interconnects individual components of an ecosystem. This results in communities that function by simultaneously coordinating their metabolic and physiologic actions. The third contribution addresses the fossil record of microorganisms, and the subsequent chapters then introduce the microbial life that currently exists in various terrestrial and aquatic ecosystems. Coverage of the geosphere addresses endolithic organisms, life in caves and the deep continental biosphere, including how subsurface microbial life may impact spent nuclear fuel repositories. The discussion of the hydrosphere includes hypersaline environments and arctic food chains. By better understanding examples from the micro biosphere, we can elucidate the many ways in which the niches of different species, both large and small, interconnect within the overlapping habitats of this world, which is governed by its microorganisms.

Biodiversity of Microbial Life places the importance and novelty of the diversity of the microbial world in perspective with the biodiversity of plants and animals. Microbial diversity has driven the evolution of all life on Earth as well as the nutrient cycles, which are key to the operation of the biosphere. Microorganisms live in all ecosystems, even extreme environments not habitable to other organisms. Noted experts including Carl Woese, the originator of the Tree of Life, and Rita Colwell, who is now Director of the National Science Foundation, offer their unique perspectives on the extent and importance of microbial biodiversity. Special emphasis is placed on: * Evolution, speciation, and contrasts between microbial biodiversity and plant and animal biodiversity * Physiological and metabolic diversity of microorganisms * Biodiversity of microbial life in terrestrial and marine environments * Symbioses between microorganisms and plants, insects, and humans * Extreme environments populated exclusively or primarily by microorganisms including thermal vents and hot springs, polar sea ice environments, and subterranean ecosystems * Microorganisms and biotechnology Biodiversity of Microbial Life is an essential resource for all biologists interested in biodiversity.

This collection of essays discusses fascinating aspects of the concept that microbes are at the root of all ecosystems. The content is divided into seven parts, the first of those emphasizes that microbes not only were the starting point, but sustain the rest of the biosphere and shows how life evolves through a perpetual struggle for habitats and niches. Part II explains the ways in which microbial life persists in some of the most extreme environments, while Part III presents our understanding of the core aspects of microbial metabolism. Part IV examines the duality of the microbial world, acknowledging that life exists as a balance between certain processes that we perceive as being environmentally supportive and others that seem environmentally destructive. In turn, Part V discusses basic aspects of microbial symbioses, including interactions with other microorganisms, plants and animals. The concept of microbial symbiosis as a driving force in evolution is covered in Part VI. In closing, Part VII explores the adventure of microbiological research, including some reminiscences from and perspectives on the lives and careers of microbe hunters. Given its mixture of science and philosophy, the book will appeal to scientists and advanced students of microbiology, evolution and ecology alike.

Microbial systems in extreme environments and in the deep biosphere may be analogous to potential life on other planetary bodies and hence may be used to investigate the possibilities of extraterrestrial life. This book examines the mode and nature of links between geological processes and microbial activities and their significance for the origin and evolution of life on the Earth and possibly on other planets. This is a truly interdisciplinary science with societal relevance.