Special Issue "Extremophiles and Extreme Environments"
Deadline for manuscript submissions: closed (30 November 2012)
Prof. Dr. Pabulo Henrique Rampelotto
Interdisciplinary Center for Biotechnology Research, Federal University of Pampa, Antônio Trilha Avenue, P.O.Box 1847, 97300-000, São Gabriel – RS, Brazil
Over the last decades, the study of extremophiles has providing ground breaking discoveries that challenge the paradigms of modern biology and make us rethink intriguing questions such as “what is life?”, “what are the limits of life?”, and “what are the fundamental features of life?”. The mechanisms by which different microorganisms adapt to extreme environments provide a unique perspective on the fundamental characteristics of biological processes present in most species. Extremophiles are also critical for evolutionary studies related to the origins of life, since they form a cluster on the base of the tree of life. Furthermore, the application of extremophiles in industrial processes has opened a new era in biotechnology. The study of extreme environments has become a key area of research for astrobiology. Extremophiles may help us understand what form life takes on other planetary bodies in our own solar system and beyond. These findings and possibilities have made the study of life in extreme environments one of the most exciting areas of research in recent decades. However, despite the latest advances we are just in the beginning of exploring and characterizing the world of extremophiles. This special issue covers all aspects of life in extreme environments. The submission of scientific perspectives, comprehensive reviews or research articles is most welcome.
Prof. Pabulo Henrique Rampelotto
Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. Papers will be published continuously (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.
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- biochemistry and molecular biology
- biodiversity and ecology
- extraterrestrial analogues
- extreme environments
- genetics, genomics and proteomics
- origin of life
- phylogeny and evolution
- physiology and metabolism
Review: Survival of the Fittest: Overcoming Oxidative Stress at the Extremes of Acid, Heat and Metal
Life 2012, 2(3), 229-242; doi:10.3390/life2030229
Received: 4 July 2012; in revised form: 14 August 2012 / Accepted: 17 August 2012 / Published: 23 August 2012| Download PDF Full-text (158 KB) | Download XML Full-text
Life 2012, 2(4), 364-376; doi:10.3390/life2040364
Received: 24 October 2012; in revised form: 8 November 2012 / Accepted: 26 November 2012 / Published: 7 December 2012| Download PDF Full-text (532 KB) | Download XML Full-text
Review: The Function of Gas Vesicles in Halophilic Archaea and Bacteria: Theories and Experimental Evidence
Life 2013, 3(1), 1-20; doi:10.3390/life3010001
Received: 29 November 2012; in revised form: 16 December 2012 / Accepted: 17 December 2012 / Published: 27 December 2012| Download PDF Full-text (308 KB) | Download XML Full-text
Life 2013, 3(1), 38-51; doi:10.3390/life3010038
Received: 23 November 2012; in revised form: 24 December 2012 / Accepted: 25 December 2012 / Published: 10 January 2013| Download PDF Full-text (154 KB) | Download XML Full-text
Review: Biohydrogen Production by the Thermophilic Bacterium Caldicellulosiruptor saccharolyticus: Current Status and Perspectives
Life 2013, 3(1), 52-85; doi:10.3390/life3010052
Received: 5 December 2012; in revised form: 6 January 2013 / Accepted: 7 January 2013 / Published: 17 January 2013| Download PDF Full-text (425 KB) | Download XML Full-text |
Life 2013, 3(1), 86-117; doi:10.3390/life3010086
Received: 29 November 2012; in revised form: 9 January 2013 / Accepted: 9 January 2013 / Published: 24 January 2013| Download PDF Full-text (1911 KB) | Download XML Full-text
Life 2013, 3(1), 118-130; doi:10.3390/life3010118
Received: 15 December 2012; in revised form: 18 January 2013 / Accepted: 21 January 2013 / Published: 24 January 2013| Download PDF Full-text (743 KB) | Download XML Full-text
Life 2013, 3(1), 131-148; doi:10.3390/life3010131
Received: 10 December 2012; in revised form: 21 January 2013 / Accepted: 22 January 2013 / Published: 29 January 2013| Download PDF Full-text (205 KB) | Download XML Full-text
Review: Periplasmic Binding Proteins in Thermophiles: Characterization and Potential Application of an Arginine-Binding Protein from Thermotoga maritima: A Brief Thermo-Story
Life 2013, 3(1), 149-160; doi:10.3390/life3010149
Received: 16 November 2012; in revised form: 11 January 2013 / Accepted: 29 January 2013 / Published: 5 February 2013| Download PDF Full-text (551 KB) | Download XML Full-text
Life 2013, 3(1), 161-180; doi:10.3390/life3010161
Received: 10 December 2012; in revised form: 28 January 2013 / Accepted: 28 January 2013 / Published: 6 February 2013| Download PDF Full-text (775 KB)
Life 2013, 3(1), 181-188; doi:10.3390/life3010181
Received: 9 November 2012; in revised form: 28 January 2013 / Accepted: 5 February 2013 / Published: 6 February 2013| Download PDF Full-text (472 KB)
Article: Evolution of Microbial “Streamer” Growths in an Acidic, Metal-Contaminated Stream Draining an Abandoned Underground Copper Mine
Life 2013, 3(1), 189-210; doi:10.3390/life3010189
Received: 29 November 2012; in revised form: 22 January 2013 / Accepted: 23 January 2013 / Published: 7 February 2013| Download PDF Full-text (1069 KB)
Article: A Laboratory of Extremophiles: Iceland Coordination Action for Research Activities on Life in Extreme Environments (CAREX) Field Campaign
Life 2013, 3(1), 211-233; doi:10.3390/life3010211
Received: 10 December 2012; in revised form: 23 January 2013 / Accepted: 5 February 2013 / Published: 25 February 2013| Download PDF Full-text (698 KB)
Review: Molecular Mechanisms of Adaptation of the Moderately Halophilic Bacterium Halobacillis halophilus to Its Environment
Life 2013, 3(1), 234-243; doi:10.3390/life3010234
Received: 11 December 2012; in revised form: 2 February 2013 / Accepted: 5 February 2013 / Published: 27 February 2013| Download PDF Full-text (438 KB) | Download XML Full-text
Article: Properties of Halococcus salifodinae, an Isolate from Permian Rock Salt Deposits, Compared with Halococci from Surface Waters
Life 2013, 3(1), 244-259; doi:10.3390/life3010244
Received: 1 January 2013; in revised form: 7 February 2013 / Accepted: 14 February 2013 / Published: 28 February 2013| Download PDF Full-text (293 KB) | Download XML Full-text
Life 2013, 3(1), 260-275; doi:10.3390/life3010260
Received: 7 December 2012; in revised form: 18 January 2013 / Accepted: 22 February 2013 / Published: 5 March 2013| Download PDF Full-text (845 KB) | Download XML Full-text
Review: Microorganism Response to Stressed Terrestrial Environments: A Raman Spectroscopic Perspective of Extremophilic Life Strategies
Life 2013, 3(1), 276-294; doi:10.3390/life3010276
Received: 4 December 2012; in revised form: 30 January 2013 / Accepted: 17 February 2013 / Published: 13 March 2013| Download PDF Full-text (223 KB) | Download XML Full-text
Life 2013, 3(2), 295-307; doi:10.3390/life3020295
Received: 14 February 2013; in revised form: 13 March 2013 / Accepted: 13 March 2013 / Published: 26 March 2013| Download PDF Full-text (699 KB) | Download XML Full-text
Review: Hot Spring Metagenomics
Life 2013, 3(2), 308-320; doi:10.3390/life3020308
Received: 7 February 2013; in revised form: 11 April 2013 / Accepted: 15 April 2013 / Published: 25 April 2013| Download PDF Full-text (147 KB) | Download XML Full-text
Article: Heterotrophic Protists in Hypersaline Microbial Mats and Deep Hypersaline Basin Water Columns
Life 2013, 3(2), 346-362; doi:10.3390/life3020346 (doi registration under processing)
Received: 4 March 2013; in revised form: 2 April 2013 / Accepted: 2 April 2013 / Published: 22 May 2013| Download PDF Full-text (2257 KB)
The below list represents only planned manuscripts. Some of these manuscripts have not been received by the Editorial Office yet. Papers submitted to MDPI journals are subject to peer-review.
Type of Paper: Editorial
Title: Extremophiles and Extreme Environments
Author: Pabulo Henrique Rampelotto
Affiliation: Interdisciplinary Center for Biotechnology Research, Federal University of Pampa, Antônio Trilha Avenue, P.O.Box 1847, 97300-000, São Gabriel – RS, Brazil; E-Mail: email@example.com
Abstract: In this Editorial, I will introduce the theme and highlight the importance of the chosen topics.
Type of Paper: Article
Title: Predator Recognition in Extremophile Fish
Authors: David Bierbach 1, Matthias Schulte 2, Nina Herrmann 2, Lenin Arias-Rodriguez 3, Jeanne Rimber Indy 3, Rüdiger Riesch 4, and Martin Plath 1
Affiliations: 1 Johann-Wolfgang-Goethe University of Frankfurt, Evolutionary Ecology Group, Max-von-Laue-Str. 13, D–60438, Frankfurt am Main, Germany; E-Mail: David.Bierbach@gmx.de (D.B.);firstname.lastname@example.org (M.P.)
2 Unit of Animal Ecology, University of Potsdam, Maulbeerallee 1, D-14469 Potsdam, Germany
3 División Académica de Ciencias Biológicas, Universidad Juárez Autónoma de Tabasco (UJAT), C.P. 86150 Villahermosa, Tabasco, Mexico
4 North Carolina State University, Department of Biology & W. M. Keck Center for Behavioral Biology, 127 David Clark Labs, Raleigh, NC 27695-7617, USA
Abstract: Failures in coping with predation exclude an individual from future reproductive opportunities, thus underpinning the importance of appropriate antipredator behavior in preventing predator-related mortalities. However, extreme habitats are often characterized by depauperate predator communities, thus potentially representing refugees for the inhabiting metazoan species. The present study was designed to investigate predator recognition mechanisms of extremophile populations of Poecilia mexicana and P. sulphuraria that either live in sulfur springs or cave habitats, which both are known to have impoverished piscine predator regimes. Our first question was whether predator recognition with regards to piscivorous fishes is still functional in Poecilia spp. inhabiting sulfur springs. We found sulfur-adapted fishes to show weaker avoidance reactions to several naturally occurring predators but the strongest difference to populations from regular clear-water habitats were found in a decreased shoaling tendency with (non-predatory) X. hellerii females that served as a control. In another experiment we compared avoidance reactions between P. mexicana from the toxic Cueva del Azufre and the adjacent toxic surface creek, the El Azufre. Cave and surface fish differed only slightly in their avoidance reactions, but surface fish clearly had the strongest reaction to the cichlid Vieja bifasciata. Our third experiment was designed to disentangle learned from innate effects of predator recognition. We used laboratory-reared (i.e., predator naïve) individuals of P. mexicana from a non-sulfidic river and compared their behavior to that of wild-caught (i.e., predator experienced) individuals from the same population; no differences in their reaction towards the presented predators were found. Overall, our results indicate that (1) predator avoidance—and thus predator recognition—is still functional in extremophile Poecilia spp. and (2) predator recognition in general has a strong genetic base.
Type of Paper: Article
Title: Molecular Mechanisms of Life in Extreme Conditions
Authors: S. Magazù and F. Migliardo
Affiliation: Department of Physics, University of Messina, V. D’Alcontres 31, 98166 Messina, Italy; E-Mail: email@example.com
Abstract: Today one of the major challenges in biophysics is to disclose the molecular mechanisms underlying biological processes. Understand the dynamic nature of hyperthermostable proteins may be the key to unravelling the mechanism responsible for the balance between rigidity, which is related to heat resistance, and molecular fluctuations at high temperatures, which account for biological function. On the other hand, cold-temperature adaptation of protein occurs, although not always in ways that would be predicted from thermophile enzymes. At cold temperatures proteins become more rigid, implying that enhancing flexibility can restore function. Another crucial suggestion comes by halophiles, organisms living in very high saline environments. It is well known that water possesses many properties that seem to make it the essential solvent for life, thus, water limitation is an extreme environment. The main goal of this work is to open up new horizons by identifying a correlation among biomolecular mechanisms, stabilization processes and surviving strategies in extremophiles. Since Nature provides precious suggestions to be applied for improving the quality of life, extremophiles are considered as useful model-systems, since the adaptation strategies they have developed can suggest innovative methodologies to be used for stabilizing biological molecules. The attention is focused on biomolecular structural and dynamical properties investigated at low and high temperature also in presence of bioprotectant systems. The strategy in such a research is based on the synergistic application of complementary spectroscopic techniques in order to get complete information in a wide time and space range.
Type of Paper: Article
Title: Quorum Sensing in Halomonadaceae
Authors: Melanie Schwab, Ali Tahrioui, Emilia Quesada and Inmaculada Llamas *
Affiliation: Department of Microbiology, Faculty of Pharmacy, University of Granada, Campus Universitario de Cartuja, 18071 Granada, Spain; E-Mail: firstname.lastname@example.org
Abstract: N-acyl homoserine lactones (AHLs) are used as extracellular signals by a variety of Gram-negative bacteria. These signals, called autoinducers, control gene expression in response to bacterial cell density in a process known as quorum-sensing (QS). In previous studies we detected the production of AHL signal molecules in Halomonas anticariensis FP35T, a moderately halophilic bacterium (Llamas et al., 2005) and since then have been able to identify and characterize the QS genes involved in the synthesis of these AHLs in this bacterium (Tahrioui et al., 2011). The next obvious step was to see whether the QS system exists in other members of the Halomonadaceae family. To this end we conducted assays with three biosensor strains, Agrobacterium tumefaciens NTL4 (pZLR4), Chromobacterium violaceum CV026 and C. violaceum VIR07 to detect the presence of AHLs in 45 halophilic species belonging to the genera Carnimonas (1), Chromohalobacter (1), Cobetia (1), Halomonas (35), Halotalea (1), Kushneria (3), Modicisalibacter (1) and Salinicola (2). To further confirm the production of AHLs, culture extracts from all the species were analysed by TLC. We also confirmed the presence of QS genes in the species in question by Southern blot hybridization and PCR amplification. The information resulting from this study is a prior requirement for future research into the role of cell-density-dependent gene regulation in extreme environments such as those inhabited by the Halomonadaceae family.
Type of Paper: Article
Title: Nanobes: A Hunt for the Smallest free-living Bacteria
Authors: Waqar Azeem Jadoon1, Katsuhiko Kashihara1, Ryosuke Nakai2 and Takeshi Naganuma1,*
Affiliations:1 Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan; E-Mail: email@example.com
2 National Institute of Genetics, 111 Yata, Mishima, Shizuoka 411-8540, Japan
Abstract: Microorganisms, particularly archaea and bacteria, are micrometer-sized and are also referred to as “microbes”. In general, the smallest free-living microorganisms are 0.2 ?m-pore-size filter is presently used in the medicine/food industry and in the field of microbiology. Recently, however, the existence of nano-microorganisms (also known as ultramicrobacteria and “nanobes”) that can pass through a 0.2 ?m-pore-size filter has been presumed, but little is known about their ecology or phylogeny. Our previous studies based on nano-culture dependent methods have been revealed that some nanobes are novel and deep-branching species that are phylogenetically important. In this study, to obtain an inventory of nanobes, we isolated 53 strains that passed through 0.2 ?m-pore-size filters from various environmental samples, including samples from the Arctic, Antarctic, and deserts. Based on 16S rRNA gene analyses, the gene sequence of 15 out of 53 strains (28%) exhibited less than 97% similarity to known culturable strains. One strain isolated from a river sample was closely related to a known obligate ultramicrobacterium from the class Actinobacteria. The genome size of this was small (ranging from 1.59 Mb to 1.74 Mb), as estimated using pulsed-field gel electrophoresis. The findings of this study suggested that obligate ultramicrobacteria might have the smallest genome of all organisms.
Type of Paper: Communication
Title: Pivotal Enzyme in Glutamate Metabolism of Poly-gamma-glutamate-producing Microbes
Authors: Makoto Ashiuchi, Takashi Yamamoto and Tohru Kamei
Affilation: Graduate School of Integrated Arts and Sciences, Kochi University, Nankoku, Kochi 783-8502, Japan; E-Mail: firstname.lastname@example.org
Abstract: An extremely halophilic archaeon Natrialba aegyptiaca secretes the L-homo type of poly-gamma-glutamate (PGA) as extremolytes. We examined the intracellular activities for glutamate metabolism and verified the occurrence of L-glutamate dehydrogenase, L-aspartate aminotransferase/L-malate dehydrogenase, and L-glutamate syntase. However, neither glutamate racemase activity nor D-aspartate aminotransferase activity was found, indicating the absence of D-glutamate suppliers. In contrast, D-glutamate-rich PGA producers essentially possess such
intracellular D-glutamate suppliers. Our study implied that D-glutamate-anabolic enzyme (e.g., glutamate racemase) is pivotal as the determinant of the structural feature and functionality of microbial PGAs.
Type of Paper: Article
Title: Surface Appendages of Archaea: Structure, Function, Genetics and Assembly
Author: Ken F. Jarrell
Affiliation: Queen’s University, Kingston, Canada; E-Mail: email@example.com
Abstract: Organisms representing diverse subgroupings of the Domain Archaea are known to possess unusual surface structures. These can include ones unique to Archaea such as cannulae and hami as well as archaella (archaeal flagella) and various types of pili that superficially resemble their namesakes in Bacteria, although with significant differences. Major advances have occurred particularly in the study of archaeal flagella and pili using model organisms with recently developed advanced genetic tools. There is common use of a type IV pili-model of assembly for several archaeal surface structures including flagella and certain pili. In addition, there are widespread posttranslational modifications of flagellins and pilins with N-linked glycans, some containing novel sugars. Archaeal surface structures are involved in such diverse functions as swimming, attachment to surfaces, cell to cell contact resulting in genetic transfer and biofilm formation. Sometimes functions are co-dependent on two surface structures. These structures and the regulation of their assembly are important features that allow cells to survive and thrive in extreme environments commonly inhabited by archaea including thermoacidophilic, hyperthermophilic, halophilic and anaerobic ones.
Type of Paper: Review
Title: Halophilic Bacteria as a Source of Novel Hydrolytic Enzymes
Authors: María de Lourdes Moreno, Dolores Pérez, María Teresa García and Encarnación Mellado
Affiliation: Department of Microbiology and Parasitology. University of Seville. C/ Profesor García González, nº2. 41012 Sevilla, Spain; E-Mail: firstname.lastname@example.org
Abstract: Hydrolases constitute a class of enzymes widely distributed in nature from bacteria to higher eucaryotes. The halotolerance of many enzymes derived from halophilic bacteria can be exploited wherever enzymatic transformations are required to function under physical and chemical conditions such as in presence of organic solvents and extremes in temperature and salt content. In the last years different screening programs have been performed in saline habitats in order to isolate and characterize novel enzymatic activities with different properties to conventional enzymes. Several halophilic hydrolases have been described, including amylases, lipases and proteases, and used for biotechnological applications. Moreover, the discovery of biopolymer-degrading enzymes offers a new solution to the treatment of oilfield waste where high temperature and salinity are typically found, while providing valuable information about heterotrophic processes in saline environments. In this work, we describe the results obtained in different screening programs specially focused on the diversity of halophiles showing hydrolytic activities in saline and hypersaline habitats, including the description enzymes with special biochemical properties. The intracellular lipolytic enzyme LipBL, produced by the moderately halophilic bacterium, Marinobacter lipolyticus showed advantages over other lipases, in particular the finding that the enzyme was active over a wide range of pH values and temperatures. The immobilized LipBL derivatives obtained and tested in regio- and enantioselective reactions, showed an excellent behavior in the production of free polyunsaturated fatty acids (PUFAs). On the other hand, the extremely halophilic bacterium, Salicola marasensis sp. IC10 showing lipase and protease activities was studied for its ability to produce promising enzymes in terms of salinity and temperature.
Type of Paper: Article
Title: Microorganisms in Extreme Temperatures: Evolution, Distribution and Molecular Mechanisms of Adaptation
Authors: Laura García-Descalzo 1, Eva García-López 1, Marina Postigo 1, Alberto Alcazar 2 and Cristina Cid 1
Affiliations: 1 Microbial Evolution Laboratory, Centro de Astrobiología (CSIC-INTA), Torrejón de Ardoz, Spain; E-Mail: email@example.com
2 Department of Investigation, Hospital Ramon y Cajal, Madrid, Spain
Abstract: There is considerable interest in investigating the microbial forms that thrive in extreme environments, especially under those environmental conditions that can provide information about evolutionary studies, applications in biotechnology or research in astrobiology. Life exists almost everywhere on the Earth. The organisms that inhabit and have adapted to these diverse environments are often classified by the extreme condition they cope with, such as temperature (psychrophiles to hyperthermophiles), pH (acidophiles and alkaliphiles), high salinity (halophiles) or pressure (barophiles). Temperature is one of the most important environmental factors for life as it influences most biochemical reactions. A reduction in temperature slows down most biochemical physiological responses, and it has been demonstrated that a reduction in temperature slows protein-protein interactions, changes the regulation of ion channel permeability and modifies enzyme kinetics. However, a temperature rise generally cannot be avoided by compensatory mechanisms, and thus the cellular components themselves, specifically the proteins, have to achieve thermostability. Here we review the main aspects on the evolution, distribution and molecular mechanisms of adaptation to extremes temperatures in psychrophilic and thermophilic microorganisms as well as summarize our latest original research results on this topic in environmental samples.
Type of Paper: Review
Title: Microbial Communication in Extreme Environments
Authors: Kate Montgomery, James Charlesworth, Rebecca LeBard and Brendan P. Burns
Affiliation: School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia; E-Mail: firstname.lastname@example.org
Abstract: Microbial communication, particularly that of quorum sensing plays critical roles in regulating gene expression in a range of bacteria. Although this phenomenon has been well studied in relation to, for example, virulence gene regulation, the focus of this article is to review our understanding of the role of microbial communication in extreme environments. Cell signaling regulates many important microbial processes and may play a pivotal role in driving microbial functional diversity and ultimately ecosystem function in extreme environments. Several recent studies have characterised cell signaling in modern analogs to early Earth communities (microbial mats), and characterization of cell signaling systems in in these communities is a key step in understanding the microbial interactions involved in function and survival in extreme environments. Cell signaling is a fundamental process that may have co-evolved with communities on the early Earth. Without cell signaling, evolutionary pressures may have even resulted in the extinction rather than evolution of certain microbial groups. One of the biggest challenges in extremophile biology is understanding how and why some microbial functional groups are located where logically they would not be expected to survive, and tightly regulated communication may be key. Finally, quorum sensing has been recently identified for the first time in archaea, and thus communication at multiple levels (potentially even inter-domain) may be fundamental in extreme environments.
Type of Paper: Review
Title: ABC Transport Proteins: The Case of the Arginine-binding Protein from Thermotoga Maritima
Authors: Alessio Ausili 1, Maria Staiano 1, Jonathan D. Dattelbaum 2, Antonio Varriale 1, Alessandro Capo 1 and Sabato D’Auria 1,*
Affiliation: 1 Laboratory for Molecular Sensing, IBP-CNR, Napoli, Italy; E-Mail: email@example.com
2 University of Richmond, Richmond, VA 23173, USA
Abstract: Arginine-binding protein from the extremophiles Thermotoga maritima is a 27.7 kDa protein possessing the typical two-domains structure of the periplasmic binding proteins family. The protein is characterized by very high specificity and affinity to bind to L-arginine also at high temperatures. These properties make the protein suitable as a sensitive probe for the design of a biosensor for L-arginine. It is an important requirement to investigate the stability of proteins when they are used for biotechnological applications. In this article we review the structural and functional features of an arginine-binding protein from the extremophile Thermotoga maritina as investigated by circular dichroism, fluorescence and infrared spectroscopy.
Type of Paper: Article
Title: A laboratory of the Extremophiles: Iceland CAREX Field Campaign
Authors: Viggó Marteinsson 1, Parag Vaishampayan 2 Angeles Aguilera 3, Jana Kviderova 4, Mauro Medori 5, Carlo Calfapietra 5, Domenica Hamisch 6, Francesca Mapelli 7, Eyjólfur Reynisson 1,Sveinn Magnússon 1, Sara Borin 7, Daniele Daffonchio 7, Calzada-Diaz8, Virginia Souza-Egipsy 3, Elena González-Toril 3 and Ricardo Amils 3
Affiliations: 1 Matis ohf. Food Safety, Environment and Genetics, Vinlandsleid 12, 113 Reykjavik, Iceland
2 Planetary Protection, All the Planets – All the Time. Jet Propulsion Laboratory, NASA, California Institute of Technology Biotechnology and Planetary Protection Group
3 Centro de Astrobiología. INTA-CSIC. Spain
4 Institute of Botany AS CR Třeboň, Czech Republic
5 Consiglio Nazionale delle Ricerche Istituto di Biologia Agroambientale e Forestale via Marconi 2-05010 Porano (TR) ITALY
6 Department of Plant Biology Technical University of Braunschweig
7 DiSTAM, University of Milan, PhD School of “Earth, Environment and Biodiversity
8 Geology Department, University of Oviedo, Spain
Abstract: Existence of live in extreme environments has been known for a long time and such environments and their habitants have been investigated by different scientific disciplines for decades. However, reports of multidisciplinary research are uncommon. In this paper we report an interdisciplinary three day field campaign conducted in the frame work of CAREX FP7 EC program with participation of experts in different fields both in life and earth science. In situ experiments and sampling was performed in a vegetated hot springs system, about 20 m long with three interconnected main pools and a mud hot spring at the beginning of the system. The temperature was 20 °C to 100 °C and the pH 2.7 to 3.8. In situ ATP measurements revealed live in all samples and PCR and PhyloChip assay showed presence of high density of both bacterial and archeal microbes. A micro coloniser with different surfaces was successfully deployed for two days and the ARISA profiles of extracted DNA showed only a few peaks compared to the pool water, indicating low bacterial diversity on the surfaces. The CO2 was significantly highest in the top pool and decreased in the second and third pool respectively. The H2S concentration was 35 fold higher in mud opening than in other pools but the SO2 remained the same. Four biofilms were observed, mainly composed by four different algae and phototrophic protist: Zygnema sp., Klebsormidium sp., Cyanidium sp. and Euglena sp, at different sites in the stream and showed differences in photosynthetic performance. Variable chlorophyll fluorescence was measured in microbial mats and Juncus plants growing in the stream at different range of temperature. Juncus plants were collected in the temperature gradient from 30 ° C to 60 °C. The fluorescence measurements indicate that the plants are not seriously damaged by the environmental conditions and are able to maintain an optimal physiological status both in terms of stomatal conductance and assimilation in spite of elevated temperatures. Plants of Juncus sp. living in the higher water temperature showed higher CO2 assimilation than that measured in Juncus sp. living at lower temperature. The three days campaign rendered interesting results due to the collaboration of experts in different fields of science and such multidisciplinary approach are recommended for holistic studies of extreme ecosystems.
Type of Paper: Review
Title: The Function of Gas Vesicles in Halophilic Archaea and Bacteria: Theories and Experimental Evidence
Author: Aharon Oren
Affiliation: Department of Plant and Environmental Sciences, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem Israel; E-mail: firstname.lastname@example.org
Abstract: A few species of extremely halophilic Archaea (Halobacterium salinarum, Haloquadratum walsbyi, Haloferax mediterranei, Halorubrum vacuolatum, Halogeometricum borinquense, Haloplanus spp.) possess gas vesicles: hollow cylindrical or spindle-shaped structures built of protein subunits, that bestow buoyancy on the cells. Gas vesicles are also produced by the anaerobic endospore-forming halophilic Bacteria Sporohalobacter lortetii and Orenia sivashensis. We have extensive information on the properties of the gas vesicles in Hbt. salinarum and Hfx. mediterranei, and the regulation of their formation was investigated in-depth. Many different functions have been suggested for gas vesicle synthesis: buoying the cells towards more oxygen-rich surface layers in hypersaline water bodies to prevent oxygen limitation, reaching higher light intensities for the light-driven proton pump bacteriorhodopsin, positioning the cells in an optimal orientation for light absorption, light shielding, reducing the cytoplasmic volume leading to a higher surface-area-to-volume ratio (all for the Archaea) and dispersal of endospores (for the anaerobic spore-forming Bacteria). Except for Hqr. walsbyi which is abundantly found in saltern crystallizer brines worldwide, gas-vacuolate halophiles are not among the dominant and most successful forms of life in hypersaline environments. There only has been little research on gas vesicles in natural communities of halophilic microorganisms, and the few existing studies have failed to provide clear evidence for their possible function. This paper presents a summary of the current status of the different theories why gas vesicles may provide a selective advantage to some halophilic microorganisms.
Type of Paper: Article
Title: Changes in Salinity Drive Shifts in Microbial Communities in Hypersaline Pools in the Salton Sea Geothermal System
Authors: Steven Bolivar , Lizette Rojas and Jesse Dillon *
Affiliation: Department of Biological Sciences, California State University Long Beach, 1250 Bellflower Blvd., Long Beach, CA, USA; email@example.com
Abstract: The Salton Sea Geothermal System (SSGS) is a geothermally active area containing mud volcanoes and hypersaline springs near the southern end of the Salton Sea, CA. Water samples were collected from springs in 2008, 2011 and 2012 to examine their microbial diversity using culture dependent and independent techniques. We hypothesized that due to their chemical and geothermal nature the hypersaline pools would contain unique microbial communities. In 2008 serial dilutions and streak plate isolations were performed to obtain pure cultures that were identified using 16S rRNA gene sequencing. Results showed the cultivation of only three haloarchaeal genera: Halorubrum, Halorhabdus and a third, previously uncultured clade. Direct environmental sequencing of 16S rRNA was employed on water samples collected in the 2011 and 2012, a period where salinity increased from 21 to 27%. This increase in salinity was accompanied by a shift away from a Haloferax-dominated community to a more diverse assemblage of members of Halobacteriaceae as well as other uncultured Euryarchaea and a single uncultured Crenarchaeal phylotype. Bacterial sequencing revealed diverse phylotypes including members of Proteobacteria, Bacteroidetes, and Firmicutes in both years, but again, little overlap in specific OTUs. These findings reveal a dynamic, remarkably diverse, prokaryotic community in the SSGS hypersaline springs.
Last update: 5 March 2013