Adaptation To Life At High Salt Concentrations In Archaea Bacteria And Eukarya

Salt is an essential requirement of life. Already from ancient times (e. g. , see the books of the Bible) its importance in human life has been known. For example, salt symbolizes destruction (as in Sodom and Gomorra), but on the other hand it has been an ingredient of every sacrifice during the Holy Temple periods. Microbial life in concentrated salt solutions has fascinated scientists since its discovery. Recently there have been several international meetings and books devoted entirely to halophiles. This book includes the proceedings of the “Halophiles 2004” conference held in Ljubljana, Slovenia, in September 2004 (www. u- lj. si/~bfbhaloph/index. html). This meeting was attended by 120 participants from 25 countries. The editors have selected presentations given at the meeting for this volume, and have also invited a number of contributions from experts who had not been present in Ljubljana. This book complements “Halophilic Microorganisms”, edited by A. Ventosa and published by Springer-Verlag (2004), “Halophilic Microorganism and their Environments” by A. Oren (2002), published by Kluwer Academic Publishers as volume 5 of “Cellular Origins, Life in Extreme Habitats and Astrobiology” (COLE), and “Microbiology and Biogeochemistry of Hypersaline Environments” edited by A. Oren, and published by CRC Press, Boca Raton (1999). Salt-loving (halophilic) microorganisms grow in salt solutions above seawater salinity (~3. 5% salt) up to saturation ranges (i. e. , around 35% salt). High concentrations of salt occur in natural environments (e. g.

Salt is an essential requirement of life. Already from ancient times (e. g. , see the books of the Bible) its importance in human life has been known. For example, salt symbolizes destruction (as in Sodom and Gomorra), but on the other hand it has been an ingredient of every sacrifice during the Holy Temple periods. Microbial life in concentrated salt solutions has fascinated scientists since its discovery. Recently there have been several international meetings and books devoted entirely to halophiles. This book includes the proceedings of the “Halophiles 2004” conference held in Ljubljana, Slovenia, in September 2004 (www. u- lj. si/~bfbhaloph/index. html). This meeting was attended by 120 participants from 25 countries. The editors have selected presentations given at the meeting for this volume, and have also invited a number of contributions from experts who had not been present in Ljubljana. This book complements “Halophilic Microorganisms”, edited by A. Ventosa and published by Springer-Verlag (2004), “Halophilic Microorganism and their Environments” by A. Oren (2002), published by Kluwer Academic Publishers as volume 5 of “Cellular Origins, Life in Extreme Habitats and Astrobiology” (COLE), and “Microbiology and Biogeochemistry of Hypersaline Environments” edited by A. Oren, and published by CRC Press, Boca Raton (1999). Salt-loving (halophilic) microorganisms grow in salt solutions above seawater salinity (~3. 5% salt) up to saturation ranges (i. e. , around 35% salt). High concentrations of salt occur in natural environments (e. g.

Various groups of microorganisms - bacteria, archaea, algae and even fungi - have adapted to a life in a hypersaline environment. Halophilic Microorganisms explores the many-fold aspects of life under these extreme conditions. Several contributions analyze the microbial communities in different hypersaline environments such as salterns, soda lakes, and the Dead Sea or salt sediments. Reviews of their biodiversity, phylogeny, and genetics are given as well as of the diverse adaptation strategies of salt-tolerant or salt-requiring microorganisms. Microorganisms that have adapted to moderate salt concentrations or to habitats with drastic fluctuations are also treated in addition to the extreme halophiles. Their physiological, biochemical and molecular mechanisms developed in response to salinity and high osmotic pressure as well as current and future biotechnological applications are presented.

Hypersaline environments are the principal habitats of petroleum deposition. They are also of intense evolutionary and ecological interest. This book presents a cross-disciplinary examination of the variety of halophilic microorganisms and their roles in modifying the ecology and geochemistry of hypersaline environments. The book also covers in detail the various inland and coastal habitats where halophilic microorganisms thrive. Geographically, hypersaline environments extend from the tropics to the poles, and from the terrestrial to the submarine. Organisms capable of living in such environments have faced unique evolutionary challenges.

The book compiles the latest studies on microorganisms thriving in extreme conditions. Microbes have been found in extremely high and low temperatures, highly acidic to saline conditions, from deserts to the Dead sea, from hot-springs to underwater hydrothermal vents- the diversity is incredible. The various chapters highlight the microbial life and describe the mechanisms of tolerance to these harsh conditions, and show how an understanding of these phenomena can help us exploit the microbes in biotechnology. The theme of the book is highly significant since life in these environments can give vital clues about the origin and evolution of life on earth, as a lot of these conditions simulate the environment present billions of years ago. Additionally, the study of adaptation and survival of organisms in such environments can be important for finding life on other planets. This book shall be useful for students, researchers and course instructors interested in evolution, microbial adaptations and ecology in varied environments.

Besides the Introductory Chapter that gives a brief overview of archaeal applications, the present book contains four chapters. The first chapter, by Castro-Fernandez et al., provides an interesting depiction of the phylum Euryarchaeota and its biotechnological applications. The second chapter, by Ben Hania and coauthors, focuses on the promotion of the idea that some specific Archaea are potential next-generation probiotics. The third chapter, by Torregrosa-Crespo et al., emphasizes the main characteristics of biocompounds from haloarchaea and their potential uses in biomedicine, pharmacy, and industry. The concluding chapter, by Mizuno et al., proposes a plasmid curing approach for improving the potential of thermophiles in various biotechnological applications and opens new perspectives on industrial valorization.

The world of halophiles is quite diverse and their representatives in three domains of life i.e. archaea, bacteria and eukarya. They are found all over the small subunit rRNA based tree of life and these micro-organisms are adapted to salt concentration up to saturation hence able to grow at >300g/l Nacl concentration. Their metabolic diversity is high as well encompassing oxygenic and anoxygenic phototrophs, aerobic heterotrophs, denitrifiers, sulphate reducers, fermenters and methanogens. The proteins of halophiles are magnificently engineered to function in a milieu containing 2-5M salt that encodes genes represent a valuable repository and resource for reconstruction and visualizing processes of habitat selection and adaptive evolution. Search for new enzymes endowed with novel activities and enhanced stability continues to be desirable purpose for important commercial production of biotechnological significance. These poly extremophiles proved excellent source of enzymes and metabolites possessing inherent ability to function in extreme conditions of high salt, alkaline pH and facilitating catalysis for industrial application in food processing, industrial bioconversion, bioremediation etc. In fact, it has just begun to realize the great potential and true extent of diversity and suitable applications if explored them judiciously. This book highlights current applications and research on halophiles to provide a timely overview. Chapters are written by expert authors from around the world and include topics of varied importance which include their role to play in enzyme production, restoration of soil fertility and plant growth , antimicrobial and biocatalytic potential, biomolecules in nanotechnology and aspects of quorum sensing. The book is divided into three sections, dealing with biodiversity, biotechnology and sustainable exploitation of halophiles. This major new work represents a valuable source of information to all those scientists interested in microorganisms in general and extremophiles in particular with respect to their innovative products and applications.