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- Herausgeber: John Wiley & Sons
- Kategorie: Lebensstil
- Sprache: Englisch
The data in this book are new or updated, and will serve also as Origin of Life and evolutionary studies. Endospores of bacteria have a long history of use as model organisms in astrobiology, including survival in extreme environments and interplanetary transfer of life. Numerous other bacteria as well as archaea, lichens, fungi, algae and tiny animals (tardigrades, or water bears) are now being investigated for their tolerance to extreme conditions in simulated or real space environments. Experimental results from exposure studies on the International Space Station and space probes for up to 1.5 years are presented and discussed. Suggestions for extaterrestrial energy sources are also indicated. Audience Researchers and graduate students in microbiology, biochemistry, molecular biology and astrobiology, as well as anyone interested in the search for extraterrestrial life and its technical preparations.
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Table of Contents
Cover
Title page
Copyright
Preface
Part I: Extremophiles in Environments on Earth with Similarity to Space Conditions
1 Volcanic Steam Vents: Life at Low pH and High Temperature
1.1 Introduction
1.2 Steam Cave and Vent Sites
1.3 Steam Cave and Vent Sample Collection
1.4 Culture Isolation
1.5 Cell Structure of Isolates
1.6 Environmental Models
1.7 Conclusions
Acknowledgments
References
2 Rio Tinto: An Extreme Acidic Environmental Model of Astrobiological Interest
2.1 Introduction
2.2 Acidic Chemolithotrophy
2.3 Rio Tinto Basin
2.4 Biodiversity in the Tinto Basin
2.5 Tinto Basin Sedimentary Geomicrobiology
2.6 The Iberian Pyrite Belt Dark Biosphere
2.7 Methanogenesis in Non-Methanogenic Conditions
2.8 Rio Tinto: A Geochemical and Mineralogical Terrestrial Analog of Mars
2.9 Conclusions
References
3 Blossoms of Rot: Microbial Life in Saline Organic-Rich Sediments
3.1 Introduction
3.2 Overview of Saline Aquatic Systems
3.3 Prerequisites of Organic Carbon-Rich Sediment Genesis in Saline Lakes
3.4 Chemistry of Recent Organic Carbon-Rich Sediments in Saline Water Bodies
3.5 Microbial Life in Saline Sapropels
3.6 Relevance of Saline Sapropels
3.7 Concluding Remarks
Acknowledgments
References
4 The Haloarchaea of Great Salt Lake as Models for Potential Extant Life on Mars
4.1 The Great Salt Lake System in the Bonneville Basin
4.2 The Transformation of an Ancient Wet Mars to a Modern Hostile Environment
4.3 Life in Evaporitic Minerals on Earth
4.6 Extant or Extinct Haloarchaea on Mars?
4.7 Conclusions and Insights
Acknowledgments
References
5 Arsenic-and Light Hydrocarbon-Rich Hypersaline Soda Lakes and Their Resident Microbes as Possible Models for Extraterrestrial Biomes
5.1 Introduction
5.2 Mars
5.3 Enceladus
5.4 Titan
References
6 Antarctic Bacteria as Astrobiological Models
Abbreviations
6.1 Introduction
6.2 Antarctica as an Analogous Environment for Astrobiology
6.3 Astrobiological Environments of Interest
6.4 Bacterial Adaptations to Extreme Environments as Analogues for Astrobiology
6.5 Antarctic Bacteria as Analogues for Astrobiology
6.6 Endemic Antarctic Bacteria used in Astrobiology
6.7 Cosmopolitan Bacteria Found in Antarctica and used in Astrobiology
6.8 Conclusion
References
7 Extremophilic Life in Our Oceans as Models for Astrobiology
7.1 Introduction
7.2 Southern Ocean Ecosystem: West Antarctic Peninsula Region
7.3 Sea Ice Decline in WAP and Ice Shelf Collapse in Amundsen Sea
7.4 Deoxygenation Leading toward Hypoxic Zone in Amundsen Sea
7.5 Microbial Extremophiles in Southern Ocean
7.6 Chemosynthetic Abyssal Ecosystems
7.7 Hydrothermal Activity in Hrad Vallis on Mars
7.8 Why Chemosynthetic Ecosystems Remind Us of Environmental Conditions When Life Originated in the Universe
7.9 Ultra-Abyssal Ecosystem: Puerto Rico Trench
7.10 Affiliations of Abyssal Life to Astrobiology: Some Perspectives
7.11 Can We Find Protozoans Such as Xenophyophores on Other Planets?
7.12 Barophilic Organisms in the Deep-Sea
Acknowledgments
References
Part II: Extremophiles in Space (International Space Station, Others) and Simulated Space Environments
8 Challenging the Survival Thresholds of a Desert Cyanobacterium under Laboratory Simulated and Space Conditions
8.1 Introduction
8.2 Endurance of
Chroococcidiopsis
Under Air-Drying and Space Vacuum
8.3 Endurance of
Chroococcidiopsis
Under Laboratory Simulated and Space Radiation
8.4 The Use of
Chroococcidiopsis
’s Survival Thresholds for Future Astrobiological Experiments
Acknowledgments
References
9 Lichens as Astrobiological Models: Experiments to Fathom the Limits of Life in Extraterrestrial Environments
9.1 Introduction
9.2 Survival of Lichens in Outer Space
9.3 Space Environment: Relevance in Space Science
9.4 Biological Effects of Space
9.5 Current and Past Astrobiological Facilities for Experiments with Lichens
9.6 Space Experiments with Lichens
9.7 Simulation Studies
9.8 Summary and Conclusions
9.9 Future Possibilities and Recommendations
References
10 Resistance of the Archaeon
Halococcus morrhuae
and the Biofilm-Forming Bacterium
Halomonas muralis
to Exposure to Low Earth Orbit for 534 Days
10.1 Introduction
10.2 Material and Methods
10.3 Results
10.4 Discussion
Acknowledgments
References
11 The Amazing Journey of
Cryomyces antarcticus
from Antarctica to Space
11.1 Introduction
11.2 The McMurdo Dry Valleys
11.3 Cryptoendolithic Communities
11.4 The Black Microcolonial Yeast-like Fungus
Cryomyces antarcticus
11.5 The Polyextremotolerance of
Cryomyces antarcticus
11.6
Cryomyces antarcticus
and its Resistance to Radiation in Ground-Based Simulated Studies
11.7
C. antarcticus
and its Resistance to Actual Space Exposure in Low Earth Orbit
11.8 Conclusion
11.9 Future Perspectives
Acknowledgments
References
Part III: Reviews of Extremophiles on Earth and in Space
12 Tardigrades – Evolutionary Explorers in Extreme Environments
12.1 Introduction
12.2 The Evolutionary Transition Towards Cryptobiotic Adaptations in Tardigrades
12.3 Cryptobiosis as an Evolutionary Adaptive Strategy
12.4 Defining Life in Cryptobiotic Animals
12.5 A Resilience Approach to the Cryptobiotic State
12.6 Molecular Mechanisms for Structural Stability in the Dry State
12.7 Tardigrades as Astrobiological Models
12.8 Tardigrades – Extremotolerants or Extremophiles?
Acknowledgments
References
13 Spore-Forming Bacteria as Model Organisms for Studies in Astrobiology
13.1 Introduction
13.2 Historical Beginnings
13.3 Revival of Lithopanspermia
13.4 Testing Lithopanspermia Experimentally
13.5 Lithopanspermia, Spores, and the Origin of Life
13.6 Interstellar Lithopanspermia
13.7 Humans as Agents of Panspermia
13.8 Survival and Growth of Spores in the Mars Environment
Acknowledgments
References
14 Potential Energy Production and Utilization Pathways of the Martian Subsurface: Clues from Extremophilic Microorganisms on Earth
14.1 Introduction
14.2 Energy Sources
14.3 Conclusion
References
Part IV: Theory and Hypotheses
15 Origin of Initial Communities of Thermophilic Extremophiles on Earth by Efficient Response to Oscillations in the Environment
15.1 Introduction
15.2 Required Conditions for the Origin of Life: Necessity of Rapid-Frequency Oscillations of Parameters
15.3 Parameters of the Environment for the Origin of Life
15.4 Formation of Prebiotic Microsystem Clusters and Their Conversion into Primary Communities of Thermophilic Extremophiles
15.5 Theoretical and Experimental Verification of the Proposed Approach
15.6 Conclusion
References
16 Extremophiles and Horizontal Gene Transfer: Clues to the Emergence of Life
16.1 Introduction
16.2 T-LUCAs, LUCAs and Progenotes
16.3 Prebiotic World and T-LUCA
16.4 Emergence of LUCA
16.5 Chemical Composition of LUCA
16.6 Emergence of Cellular Life Forms
16.7 Evidence for Cellular Life Forms
16.8 The Hypotheses: Genetic First vs. Metabolism First
16.9 Extremophiles
16.10 The Viral Connection to the Origin of Life
16.11 Horizontal Gene Transfer (HGT)
16.12 Mechanisms of HGT
16.13 Clues to the Origins of Life and a Phylogenetic Tree
16.14 Conclusion
Acknowledgment
References
17 What Do the DPANN Archaea and the CPR Bacteria Tell Us about the Last Universal Common Ancestors?
17.1 Introduction
17.2 The Discovery of DPANN and CPR
17.3 Common Features of CPR and DPANN
17.4 LUCA and the Deep-Rootedness of CPR and DPANN
17.5 Short Branches, Deep Branches and Multiple LUCAs
17.6 Viruses: LUCA without ‘Cellular’
References
18 Can Biogeochemistry Give Reliable Biomarkers in the Solar System?
Abbreviations
18.1 Evidence of Life in the Solar System
18.2 Extremophiles on Earth
18.3 Extremophiles in Low Orbits Around the Earth
18.4 Have There Been Extremophiles on the Moon?
18.5 Have There Been Extremophiles on Mars?
18.6 Europa is a Likely Location for an Extremophilic Ecosystem
18.7 Are There Other Environments for Extremophiles in the Solar System?
18.8 Are There Environments for Extremophiles on Exoplanets?
References
Index
List of Illustrations
Chapter 1
Figure 1.1
Steam condenser: (a) Collector body is a stainless cylinder, 1 or 2 l...
Figure 1.2
Steam deposit sampling sites: (a) Nonsulfur steam cave site Hawai’i 1...
Figure 1.3
Steam caves/vents spectra: (a) Hawai’i H1 nonsulfur cave. (b) Lassen ...
Figure 1.4
Sulphur Works nonsulfur cave SW1 culture pH 4.5, 80 °C. (a) Phase con...
Figure 1.5
Sulphur Works sulfur cave SW3 culture pH 4.5, 85 °C. (a) Phase contra...
Figure 1.6
Sulphur Works iron vent SW4 culture, pH 4.5, 80 °C. (a) Phase contras...
Figure 1.7
FISH labeled culture pH 4.5, 80 °C, isolated from iron vent, Sulphur ...
Figure 1.8
Scanning electron microscope images of steam vent isolates. (a) Cell ...
Figure 1.9
Iron-oxidizing environment. Heated rainwater from magmatic heat conve...
Figure 1.10
Salt cave environment. (1) Rainwater recharge of the Hawaiian ground...
Chapter 2
Figure 2.1
View of colorful filamentous algae in the red waters of the origin of...
Figure 2.2
Comparison between ferruginous deposits of the Burns Formation (a) cr...
Figure 2.3.
Processing the selected cores for the generation of samples in an an...
Figure 2.4
Borehole BH11 drilling in Peña de Hierro. (Image credit: the authors)...
Figure 2.5
Bacteria detected using the CARD-FISH probe EUB338-1 at 420 mbs. (Ima...
Figure 2.6.
Preservation of different traces of life in the oldest Rio Tinto ter...
Chapter 3
Figure 3.1
Macroscopic aspect of black mud freshly collected from hypersaline me...
Figure 3.2
Relative abundance estimation for major taxa in organic-rich sediment...
Figure 3.3
Major steps of anaerobic organic matter degradation to methane, CO
2
a...
Chapter 4
Figure 4.1.
Great Salt Lake is visible from space in its location in western Nor...
Figure 4.2.
Great Salt Lake (GSL) and Bonneville Salt Flats (BSF) in the context...
Figure 4.3.
Mineral formation at Great Salt Lake. (a) The beach is expansive as ...
Figure 4.4.
Evaporites on Earth and Mars.
(
a) Bonneville Salt Flats in the Great...
Figure 4.5.
Magnetic fields of Mars and Earth. (a) Schematic of the solar wind i...
Figure 4.6.
Analogue mineralogy: (a) Gypsum “box-work” at Gale Crater on Mars as...
Figure 4.7.
Halite crystals from Great Salt Lake. (a) Halite hopper crystals, co...
Figure 4.8.
Gypsum crystals contain haloarchaea. (a) Blade-like gypsum crystals ...
Chapter 5
Figure 5.1.
The author (second from left) attired as a spaceman and budding astr...
Figure 5.2.
Three photographs of the playa of Searles Lake, California, with its...
Chapter 6
Figure 6.1.
Extremophiles and Extremotrophs by category. Characterizing the para...
Chapter 7
Figure 7.1
Note the disappearance of sea ice at the tip of the Antarctic Peninsu...
Figure 7.2
Progression of loss of sea ice from the edge of the Amundsen Sea from...
Figure 7.3
Reduced pH around 300 to 450 meters where krill embryos develop. (Fig...
Figure 7.4
Transect from 20 N to 65 N showing low oxygen (hypoxia zone) only in ...
Figure 7.5
Transect from 20 N to 65 N, showing appearance of reduced oxygen zone...
Figure 7.6
Typical vent community. (Figure courtesy of Dr. Fred Grassle).
Figure 7.7
Giant tube worms
Riftia pachyptila
clustering on hydrothermal vent. (...
Figure 7.8
Vent zoarcid fish
Diplacanthaopora
sp. with tube worm
R. pachyptila
i...
Figure 7.9
(a)
Rimicaris hybisae
and (b)
Rimicaris exoculata.
(Figures courtesy ...
Figure 7.10
Color image of a lava-rise pit formed by gradual thickening of a lav...
Figure 7.11
Artist’s interpretation of ultra-abyssal life in the Puerto Rico Tre...
Figure 7.12
Europa. (Image credit: NASA).
Figure 7.13
Xenophyophore from the Galapagos Rift. The “giant amoeba” (belonging...
Chapter 8
Figure 8.1
E. Imre Friedmann and Maria Grilli Caiola while attending the Interna...
Figure 8.2
E. Imre Friedmann’s letter on the history of desert strains of Chrooc...
Chapter 9
Figure 9.1
Foton satellite with BIOPAN-5 facility orbiting the Earth. (Courtesy ...
Figure 9.2
Opened Biopan-5 facility with experiment LICHENS surrounded in red. (...
Figure 9.3
EXPOSE-E on the International Space Station with experiment LIFE. (Co...
Figure 9.4
EXPOSE-R2 on the International Space Station with experiment BIOMEX. ...
Figure 9.5
Lichens (a)
Rhizocarpon geographicum
and (b)
Xanthoria elegans.
(Imag...
Figure 9.6
(a) Confocal scanning laser microscopy image showing high vitality of...
Figure 9.7
The vagrant lichen species
Circinaria gyrosa.
(Courtesy of L. García ...
Figure 9.8
LITHOPANSPERMIA/STONE Experiment: (left) Location at the heat shield ...
Figure 9.9
LIFE experiment: Lichens thalli, lichens mycobionts cryptoendolithic ...
Figure 9.10
(left) Zvezda module at International Space Station; (right) EXPOSE-...
Figure 9.11
Percentage of activity of photosystem II of lichen species measured ...
Chapter 10
Figure 10.1.
Setup of the EXPOSE-R2 mission tray. (a) Close-up of a single-tray ...
Figure 10.2.
Survival of desiccated
Hlm. muralis
(a) and
Hcc. morrhuae
(b) cells...
Figure 10.3.
Survival of
Hcc. morrhuae
, embedded in a biofilm of
Hlm. muralis
an...
Figure 10.4.
Survival of
Hcc. morrhuae
(embedded in the biofilm of
Hlm. muralis
)...
Figure 10.5.
RAPD-PCR to visualize the damages accumulated in DNA of Hcc. morrhu...
Chapter 11
Figure 11.1.
(a) Sandstone slopes in the McMurdo Dry Valleys (Southern Victoria ...
Figure 11.2.
Resistance to space-relevant radiation in dried condition. Cultivat...
Figure 11.3.
Understanding the role of melanin: Metabolic activity recovery afte...
Figure 11.4.
Resistance of
C. antarcticus
to simulated Mars-like conditions outs...
Figure 11.5.
BIOMEX experiment outside the ISS: TEM micrographs of cells of C. a...
Chapter 12
Figure 12.1.
Tardigrades in active hydrated state (left) and in the desiccated a...
Figure 12.2.
The ball and cup heuristics as used in resilience science to illust...
Figure 12.3.
The main results from the TARDIS experiment performed within the BI...
Chapter 14
Figure 14.1.
Energetics of common hydrogen-utilizing microbial reactions in the ...
Figure 14.2.
Possible sources and sinks for methane on Mars. (Reprinted with per...
Figure 14.3.
Microbial iron redox cycling showing the co-dependent operation of ...
Figure 14.4.
A summary of the list of potential electron donors and acceptors av...
Chapter 15
Figure 15.1.
Scheme of the conversion of a nonequilibrium prebiotic microsystem ...
Figure 15.2.
Pressure dynamics of water-steam mixture in well No. 30 in 2004 (Mu...
Figure 15.3.
Arising of embryo of the initial community in hydrothermal fluid mi...
Chapter 16
Figure 16.1.
(a) Transmutation of species as depicted on page 36 of Darwin’s not...
Figure 16.2.
(a) Depicts a typical bilayer vesicle formed when (for example) dec...
Figure 16.3.
The depicted scale and typical results obtained by Schopf. (Credit: ...
Figure 16.4.
(a) Hot spring at Wai-O-Tapu park, New Zealand. (b) Example of blac...
Figure 16.5.
(a) Images showing examples of various endoliths; for example, the ...
Figure 16.6.
(a) Schematic illustration of the process of transformation. (b) Sc...
Figure 16.7.
(a) The phylogenetic tree of life is a theoretical construct to exp...
Figure 16.8.
(a) Shows that the evolutionary-time-frame is 2 units from the ance...
Chapter 17
Figure 17.1.
The tree of life. Humans and other eukaryotes are represented by th...
Figure 17.2.
If all extant cellular life on Earth were known to us, the last uni...
Figure 17.3.
The Deep Branch Fallacy. In tree 1, A and D are equally representat...
Tables
Chapter 1
Table 1.1
Fumarole sampling locations and physical properties.
Table 1.2
Analysis of steam deposits in Hawai’i and Lassen fumaroles.
1
Chapter 3
Table 3.1
Composition of recent sapropels from selected, well-investigated brack...
Table 3.2
Metabolic reactions with low Gibbs free energy changes that potentiall...
Chapter 4
Table 4.1.
Haloarchaea species diversity discovered in the Great Salt Lake north...
Table 4.2.
Haloarchaea superpowers; survival strategies for life at high salinit...
Chapter 6
Table 6.1.
Comparison of main environmental data of Earth to space and celestial...
Table 6.2.
Comparison of some of the environmental extremes found in the Antarct...
Table 6.3.
Antarctic environmental conditions potentially driving bacterial adap...
Table 6.4.
Bacteria thought to be endemic to the Antarctic and used as astrobiol...
Chapter 9
Table 9.1
Exposure conditions during the BIOPAN and during the EXPOSE experiment...
Chapter 10
Table 10.1.
Single stress factors tested during EVT (environmental verification ...
Table 10.2.
Hcc. morrhuae
and
Hlm. muralis
were exposed to a combination of spac...
Table 10.3.
Relative lesion frequency of
Hcc. morrhuae
16S rRNA gene following e...
Guide
Cover
Table of Contents
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Scrivener Publishing
100 Cummings Center, Suite 541J
Beverly MA, 01915-6106
Astrobiology Perspectives on Life of the Universe
Series Editors: Richard Gordon and Joseph Seckbach
In his 1687 book Principia, Isaac Newton showed how a body launched atop a tall mountain parallel to the ground would circle the Earth. Many of us are old enough to have witnessed the realization of this dream in the launch of Sputnik in 1957. Since then our ability to enter, view and understand the Universe has increased dramatically. A great race is on to discover real extraterrestrial life, and to understand our origins, whether on Earth or elsewhere. We take part of the title for this new series of books from the pioneering thoughts of Svante Arrhenius, who reviewed this quest in his 1909 book The Life of the Universe as Conceived by Man from the Earliest Ages to the Present Time. 1e volumes in Astrobiology Perspectives on Life of the Universe will each delve into an aspect of this adventure, with chapters by those who are involved in it, as well as careful observers and assessors of our progress. Guest editors are invited from time to time, and all chapters are peer-reviewed.
Publishers at Scrivener
Martin Scrivener ([email protected])
Phillip Carmical ([email protected])
Extremophiles as Astrobiological Models
Edited byJoseph Seckbach and Helga Stan-Lotter
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Preface
Foreword
Life on Earth is ubiquitous, with most organisms living in so-called “normal” environments that we consider ambient habitats. Many microorganisms are known to tolerate and resist harsh and extreme external conditions; they are called extremophiles [6; 7]. Among them are Archaea, Bacteria, fungi, plants and microscopical animals, like the tardigrades. Some of these microorganisms are living at elevated pressure, such as in the depths of the oceans; some are able to tolerate extreme temperatures and pH values, desiccation or strong UV radiation. Some extremophiles may be under the stress of more than one factor, and we refer to them as polyextremophiles [8]. The severe environments most probably resemble the conditions on early Earth. Some of the extremophiles may thus be considered as “living fossils” since their environments resemble the conditions that have existed during the time when life is thought to have arisen on Earth, more than 3.8 billion years ago.
Are there any life forms outside the terrestrial regions? Why should such extremophilic organisms not also live in extraterrestrial places? If these organisms can thrive in such harsh conditions on Earth, they should be able to exist on celestial bodies with similar conditions.
The origin of life on Earth is still unknown. Life has been suggested to evolve from hot springs, geysers, ocean depths, volcanoes, etc. Some scientists think that life originated in cold environments, and suggest connections to bacteria in extremely cold territories like Antarctica or the North Pole.
Who and what is in this new book?
In 1995 the first extrasolar planet was discovered by Mayor and Queloz [4]; now that number is 4,301 [5; July 2020] and the question of whether there is life—possibly intelligent life—in space is more timely than ever.
Research is hampered by the fact that no other life-bearing planet has been found which could serve as a comparison. Or has it? The question of whether there is—or was—life on Mars, at least in the form of simple microbes, has not yet been solved unequivocally [1]. The Jovian moon Europa and the Saturnian moons Titan and Enceladus are also considered promising candidates for worlds with life [3].
This book deals with the description of extremophilic microorganisms which live in environments with similarities to those known from several planets and moons in the solar system. Also, on Earth, environmental conditions occur which are lethal or at least harmful to many organisms, but specialists nevertheless survive or even thrive under these conditions.
The first chapters (Part I) consider extremophiles which are found in environments with possible or very likely similarities to the conditions on extrasolar planets or other celestial bodies. For example, the pH can be very low, such as 3.0, and temperatures can be high (> 90 °C), such as in volcanic steam vents or fumaroles (Bizzoco and Kelley). Using a special collector for the steam, the authors discovered a great diversity of thermophiles, which mostly belong to the Archaea.
Acidophiles are of special interest because their chemolithotropic metabolism obtains energy from reduced minerals, thus creating the extreme acidic conditions in which they thrive. An extensive geomicrobiological characterization of the Rio Tinto basin in Spain has proven the prominent role of the iron cycle in the ecosystem (Amils and Fernández-Remolar). The identification of iron sulfates and oxides on Mars, analogous to those generated in the Tinto basin by microbial metabolism, has made Rio Tinto one of the best geochemical and mineralogical terrestrial Mars analogues.
Recent findings suggest that microbiomes which are found in brackish, marine and hypersaline modern sapropels (‘rotten mud’) include yet uncultured Archaea that may be close to the evolutionary roots of eukaryotes and life itself (Andrei et al.). The extreme geochemistry of certain sapropels, as well as their relevance in the preservation of biomarkers, might qualify them as analogs for early Earth habitats or for the exploration of habitable extraterrestrial milieus.
Expansive evaporite mineral deposits on Mars are evidence of ancient lacustrine systems (Bayles et al.). As the surface water dried up, hypersaline lakes would have filled the ancient lake basins. Halite and gypsum contain fluid inclusions where microorganisms may be entombed over geologic time. Haloarchaea are also resistant to other extremes, such as high radiation doses. These properties make them excellent analogues for life that could have existed in the hypersaline lakes on Mars and perhaps remained preserved in the evaporitic minerals there.
Historical observations of NASA’s activities towards Mars (Viking experiments) are presented by Oremland, including the early enthusiasm for astrobiology (although that name was not yet coined in the 1970s). His research focuses on soda lakes, which are alkaline (pH ≥ 9.5), often hypersaline (salinity > 35 g/L), mineral-rich water bodies, and their amazingly intense microbial populations, such as haloalkaliphilic arsenotrophs, which are capable of using As(V), Fe(III), or S(0) as electron acceptors. The possibility of similar environments on Mars or planetoids (Enceladus, Titan) is considered.
Antarctica is a rich source of extremophiles, not just psychrophiles, but polyextremophiles which are exposed to unusually high level of UV radiation for Earth, hyperarid conditions, hypersaline conditions, and extremely low nutrients (Abbott and Pearce). Notable similarities exist to conditions known to occur on Mars, or to what is known of the icy moons of Jupiter and Saturn.
Today, Earth harbors vast oceanic ecosystems—most of them only barely explored— which support life (psychrophilic, barophilic and chemosynthetic) adapted to conditions that may occur in other planets in the universe (George). Climate change-induced processes may slow down major ocean currents, such as the Antarctic Bottom Water (ABW) flowing into the lower hadal or ultra-abyssal zone at a depth greater than 8,000 meters, with potential creation of hypoxic hadal zones at extreme ocean depths and its consequences.
In Part II, experiments with extremophiles in space, e.g., on the International Space Station, are presented. Bacteria as well as Archaea, lichens, fungi, algae and tiny animals (tardigrades) are now being investigated for their tolerance to extreme conditions in simulated or real space environments. Experimental results from exposure studies on the International Space Station and on space probes for up to 1.5 years are presented.
Anhydrobiotic cyanobacteria of the genus Chroococcidiopsis possess a remarkable resistance to desiccation and radiation. These cyanobacteria were exposed to laboratory simulations that mimic planetary conditions, such as dryness, UV and gamma radiation, and also to real space conditions on the International Space Station (Billi). The resistances found are discussed with respect to lithopanspermia.
Lichen species, which are composite organisms consisting of algae or cyanobacteria in a mutualistic relationship with filaments of various fungi, are well-known survivors of the most stressful environments. The first space experiments were carried out with Rhizocarpon geographicum and Xanthoria elegans in the Foton-M2 satellite in 2005 (de la Torre Noetzel and Sancho). Space simulation and space exposure experiments have focused on these and other lichen species, demonstrating their high capacities of survival and recovery.
The halophilic archaeon Halococcus morrhuae and the biofilm-forming bacterium Halomonas muralis were exposed to space conditions during the EXPOSE-R2 mission. Hlm. muralis was much less resistant to extreme conditions than Hcc. morrhuae (Leuko et al.). Exposure to outer space had a strong detrimental effect on the survival and genomic stability of Hcc. morrhuae; however, Hcc. morrhuae could be re-cultivated from samples exposed on the ISS for up to 534 days. These results add to our understanding that life may be able to survive the travel through space.
The cryptoendolithic endemic black fungus Cryomyces antarcticus was isolated from sandstone collected in the McMurdo Dry Valleys in Antarctica, a place which is considered the coldest hyperarid desert on Earth and one of the best terrestrial analogues for Mars (Onofri et al.). C. antarcticus is able to survive intense ionizing radiation, probably due to the presence of a highly melanized thick cell wall.
In Part III, several authors provide reviews on specific topics, such as Jönsson on the properties of tardigrades (also called water bears), which were used in the Foton-M3 mission and survived a combined exposure to space vacuum, cosmic radiation and UV radiation. The evidence for their metabolic arrest (cryptobiosis) and multiple resistances to environmental extremes make these tiny animals (size ca. 1 mm or less) particularly useful astrobiological models.
Nicholson reviews bacterial endospores, the very first model of cells used for astro-biological purposes, and demonstrates their connection to and impact on the history of origin-of-life studies as well as the concept of lithopanspermia. Modern experimental testing of this concept involves using ballistic devices to simulate the interplanetary exchange of rocks containing bacterial spores.
Paul and Mormile consider the very basic problem of available sources of energy for microbial life on Mars. They analyzed the utilization of several available compounds— hydrogen and methane as key molecules, but also iron, sulfur and others—by extremophilic microorganisms, providing numerous examples of a wide range of well-described biochemical reactions. A cautious look at the possible connection to the energy demands of potential human settlements is also included.
Part IV contains articles on theory and hypotheses. The search for extraterrestrial life is closely connected with the question of the origin of life on Earth and its early evolution. Newer proposals emphasize the importance of environmental oscillations and suggest experiments for testing this on a laboratory scale (Kompanichenko and Levchenko).
Several theories exist on the existence of a prebiotic world, which are outlined by Jheeta. The implications of the vast—and probably still underestimated—horizontal gene transfer and the potential role of viruses and RNA are presented. One or several transitional (T)-LUCAs (last universal common ancestor) are postulated as leading to the emergence of the first cells.
Recent evidence for an unprecedented archaeal diversity (uncultivated strains) and novel bacterial phyla, due to significantly improved sampling of the subsurface and whole genome sampling, has greatly extended our views on the LUCA of all life, including viruses and their consideration as ancient forms of life (Lineweaver).
Instrumentation for the search of sulfur isotopes as biomarkers for potential habitats for extremophiles in the Solar System is proposed by Chela-Flores, together with a discussion of the pros and cons for possible life on the celestial bodies close to Earth (Moon, Mars, Europa, Titan, and the icy moons).
Conclusions
The search for extraterrestrial life has been declared as a goal for the 21st century by NASA, ESA and other space agencies. For meaningful missions, careful planning of sites to be selected and knowledge of their properties is essential. The study of extremophiles on Earth has already provided rich information about the physico-chemical limits of life; these studies need to be extended with a focus on the specific technical requirements of future space missions. For Mars, a recent report suggested four potential sites for extremophiles—caves, deep subsurface, ices, and salts—and outlined measurement techniques and detection methods [2].
Acknowledgments
We thank all authors for their contributions and the reviewers of chapters for their work. Thanks also go to Martin Scrivener and Richard Gordon for their helpful suggestions and excellent cooperation.
References
1. American Museum of Natural History. (https://www.amnh.org/learn-teach/curriculum-collections/cosmic-horizons-book/fossil-microbes-mars), accessed May 29, 2020.
2. Carrier, B.L., Beaty, D.W., Meyer, M.A., Blank, J.G., DasSarma, D.J., Des Marais, D.J., Eigenbrode, J.L. et al., Mars extant life: What’s next? Conference Report. Astrobiology, 20, 6, 785–824, 2020.
3. Lunine, J.I., Ocean worlds exploration. Acta Astronaut., 131, 123–130, 2017.
4. Mayor, M. and Queloz, D., A Jupiter-mass companion to a solar-type star. Nature, 378, 6555, 355–359, 1995.
5. The Extrasolar Planets Encyclopaedia, (http://exoplanet.eu; accessed July 31, 2020).
6. Rothschild, L.J. and Mancinelli, R.L., Life in extreme environments. Nature, 409, 1092–1101, 2001.
7. Seckbach, J. (Ed.), Enigmatic Microorganisms and Life in Extreme Environments, Kluwer Academic Publishers, Dordrecht/Boston/London, 1999.
8. Seckbach, J., Oren, A., Stan-Lotter, H. (Eds.), Polyextremophiles: Life under Multiple Forms of Stress, Springer Dordrecht, Heidelberg, New York, London, 2013.
Joseph Seckbach and Helga Stan-Lotter
Part IEXTREMOPHILES IN ENVIRONMENTS ON EARTH WITH SIMILARITY TO SPACE CONDITIONS
1Volcanic Steam Vents: Life at Low pH and High Temperature
Richard L. Weiss Bizzoco* and Scott T. Kelley
Department of Biology, San Diego State University, San Diego, California, USA
Abstract
Following meteoric recharge, fundamental components of volcanic magma (heat, gases and ions) are carried by rising steam from the subsurface through porous and fractured passageways until the heated steam exits at the surface in caves and vents. Deposits accumulate as steam condenses on cooler cave ceilings and vent walls, leaving evaporites, precipitates, sublimates, and particulates in solid form along with vapor condensates. Over time these become available in sufficient quantities in matrix material to support growth of microorganisms. This study describes and characterizes some of the chemistry of steam vent habitats, the means developed to sample steam and steam deposits aseptically, using a steam condenser and a simple sample collection device. We describe and evaluate controls producing contamination-free steam and steam deposit samples for analysis. The chemistry of different types of vents studied so far includes nonsulfur, sulfur and iron. Recent iron vent and salt cave studies will be considered. These steam bathed sites harbor both known and unknown organisms, typically but not exclusively, Archaea, that have been grown or are present in quantities sufficient to identify by cloning, and then isolate and describe some of their physical features as well as the means used for enrichment and isolation. We report two recent new isolates from an extreme non-sulfur cave and an iron vent (~pH 3; 85.5 °C) and describe revised equipment used to capture steam samples from low pH high-temperature cave/vent habitats. Overall, we report on steam cave/vent habitats, sampling, enrichment, isolation and identification, as well as structural features of isolated organisms found at low pH and near maximum temperatures for these high-altitude geothermal habitats. Our understanding of the features of life in one of the most extreme and abundant habitats that provide the limits of existence will help produce a model for life beyond Earth’s extreme boundaries.
Keywords: Acid, Archaea, fumarole, iron, nonsulfur, salt, sulfur, thermophile
1.1 Introduction
A prominent feature of many, if not most geothermal fields is the presence of abundant fumaroles (i.e., steam vents). These are especially visible early in the day when the cool air condenses the rising water vapor into smoke-like clouds. These geothermal steam vents differ chemically from each other and can be grouped into nonsulfur, sulfur and iron fumaroles [1.1]. A number of different chemical processes cause steam deposits to form and give individual vents their main chemical identities. Fumaroles can issue a greater or lesser volume of steam depending on the meteoric water supply, temperature, size, and type of vent. In turn, steam deposits are caused by condensation of steam on cooler cave or vent walls or surfaces. This allows their collection by sampling of steam cave or vent surfaces at the point of contact between steam and cave surface and yields distinctive chemical-microbiological samples. These samples result from one of the following processes: 1) evaporation of soluble ions leaving deposits of salts or evaporites; 2) oxidation of soluble Fe(II) ions to insoluble precipitates such as iron oxides, hydroxides, or oxyhydroxides; 3) gases like H2S rise with steam, becoming less soluble and form into solid sublimates that are oxidized into sulfur deposits; 4) steam and particulates travel over cave surfaces leading to adhesion or entrapment within the surface matrix; and 5) ammonia forms as vapors rising with steam [1.11] [1.13] and concentrates at the steam deposit site [1.1] comparable to the way H2S acts in acidic systems.
In this study we describe the use of a portable steam collector designed for sterile microbiological sampling to capture volcanic steam and microbial steam vent life forms. Steam exits fumaroles in a continuous flow or in bursts that are both hot and diffuse. This often makes collecting a sufficient quantity of steam vapors for microbiological analysis a challenging prospect. Our collector uses a difference in temperature to condense steam, resulting in hot water guided into a sterile polypropylene collection tube (Figure 1.1). The condenser captures up to 2–3 mL min-1 from vents above 90 °C, making on-site collection a practical procedure. Once we collected steam water samples, we examined the condensed water samples with DNA staining (using DAPI) for microbial life and also established cultures to grow the steam vent microorganisms from locations in Hawai’i, California, New Mexico, Wyoming and Russia. By determining the number of organisms in condensed water samples and the steam flow rate, we were able to estimate the overall fumarole dispersion, as steam vapors exited different types of fumaroles. We concentrated our efforts on the Archaea, a group of organisms known to live at pH and temperature extremes. In some extreme fumaroles, we found these to be the only organisms present. Finally, we sampled both steam and steam cave/vent deposits and found that the deposit matrix formed at the steam-cave surface contact site served as a unique concentrating device to entrap nutrients critical for the survival of specific steam vent organisms. Hawai’i has so far presented the most chemically diverse types of steam vents, making this an ideal site for examining extremophiles and Archaea as a model for life beyond Earth’s boundaries. Other collection sites provide unique steam cave/vent features that increase our understanding of fumarolic microbial life.
Figure 1.1 Steam condenser: (a) Collector body is a stainless cylinder, 1 or 2 liters with overlying funnel condenser and silicone plugged guide rod. Central collection tube holder lies near cylinder bottom. (b) Cutaway diagram showing interior of condenser parts. (c) Condenser has a fitted splash shield to prevent water loss and contamination. Mounting feature (black) allows extension pole or tripod attachment. Operation: Ascending steam contacts underside of cooler cone funnel, transfers heat to water reservoir above, steam condenses to water that drains down funnel to guide rod, and into 50 mL sterile screw cap collection tube. Following collection, sterile tube is capped. (Image credit: the authors).
1.2 Steam Cave and Vent Sites
Samples of steam were collected from fumaroles in four permanently protected geothermal areas, Lassen Volcanic National Park, Hawai’i Volcanoes National Park, Valles Caldera National Preserve, and Solfatara Crater, Italy (Table 1.1). Our Hawai’i Volcanoes National Park sites are coded, as part of our collection agreement with the park. These sites have a wide and interesting variety of chemical steam caves and vents not seen in other geothermal areas. Our choice of Hawai’i as a site with an active volcano proved to be interesting. In many ways, its basaltic lava flows resemble those of our nearby planet Mars, both chemically and physically providing a match for using Earth’s extremophile life as a model for life on other planets. Mars is one of those planets close enough for experimental approaches and applications.
In active steam caves, meteoric waters characteristically descend through porous and fractured surface lava and eventually meet upward convection of heat and rising volcanic gases. Heat generates abundant steam that rises as a vapor-gas mixture through fractured lava crevices and fissures towards the surface. Near the surface, passageways—both horizontal and vertical—allow the vapors to condense on the cooler cave ceilings and walls, depositing characteristic chemical signatures and forming a matrix-like material rich in nutrients for extreme microorganisms. The steam exits the cave or vent opening and provides a diffused smoke-like flow known as a fumarole. Venting steam commonly proceeds in an artesian or burst flow. With large volumes of steam, visibility of the cave interior or vent opening can be obscured. Steam cave/vent openings can be small on the order of a few centimeters or large, one to three meters or larger for wide steam vents or vertical caves. Our selection of steam caves was based on the idea that while we and others [1.7] [1.10] [1.12] [1.16] had already investigated and identified organisms, especially Archaea in steam vents, there was not much information on organisms from those steam caves/vents regarding their in-situ appearance and some of the sites where they have previously been isolated left gaps in our information on the physical appearance of steam vent microorganisms at the structural level.
1.3 Steam Cave and Vent Sample Collection
The steam cave and vent sites were selected for their chemical properties. These were initially recognized in flowing hot springs as iron and sulfur. Here, deposition of iron occurred in the anoxic zone of the spring and at the point of disappearance of iron at the anoxic/oxic interface, sulfur deposition took place and finally iron deposits formed on the existing sulfur in the anoxic/oxic zone. The same phenomenon can be seen in very small sulfur caves where the interior has no sulfur, the cave opening is small and sulfur deposition occurs only at the anoxic/oxic interface or on the outer oxic surface, sometimes along with iron deposits over sulfur. The other categories, nonsulfur and salt (the latter so far only seen in Hawai’i), represent a departure from the flowing hot spring analogy. Nonsulfur steam caves have not yet been fully categorized, although unusual thin filamentous organisms have been enriched from the H5 salt cave, and from sulfur caves such as SW 3 in Lassen. Nonsulfur caves farther below are considered for their solid surface chemistry by means of energy dispersive X-ray microanalysis (EDX). Sampling of steam cave or vent ceilings depends on the nature of the surface. With highly acidic solfatara areas, cave ceilings can be delicate and sometimes only careful hand sampling is essential. With deeper nonsulfur caves sometimes encountered in Hawai’i, this is less of a problem because the cave ceilings are formed of hard lava and only shallow samples are obtained. However, sampling through a small opening into a deep cave interior is not without its challenges, principally resulting from the high level of heat encountered, with or without leather gloves.
Table 1.1 Fumarole sampling locations and physical properties.
Location
pH
Temp (°C)
Type
Chemistry
Hawai’i Volcanoes National Park
1
Hawai’i (1)
5.5
65.0
Cave
Nonsulfur
Hawai’i (2)
5.2
68.0
Cave
Nonsulfur
Hawai’i (3)
3.0
82.0
Cave
Sulfur
Hawai’i (4)
3.0
82.0
Cave
Iron/sulfur
Hawai’i (5)
5.0
68.0
Cave
Salt
Hawai’i (6)
4.5
66.0
Cave
Salt/sulfur
Lassen Volcanic National Park
2
Sulphur Works, lower (1)
4.5
87.0
Cave
Nonsulfur
Sulphur Works, lower (2)
3.2
93.0
Vent
Sulfur
Sulphur Works, lower (3)
4.0
91.5
Cave
Sulfur
Sulphur Works, upper (4)
3.0
85.5
Vent
Iron
Sulphur Works, upper (5)
2.5
81.2
Cave
Iron
Valles Caldera National Preserve
3
Sulphur Springs, New Mexico
2.0
89.0
Cave
Nonsulfur
Pozzuoli, Italy
4
Solfatara Crater
3.0
94.0
Vent
Sulfur
1 June 2016 sampling
2 Oct 2018 sampling
3,4 included for comparison
1.3.1 Steam Collection
Samples of steam were collected from fumaroles in four permanently protected geothermal areas, Lassen Volcanic National Park, Hawai’i Volcanoes National Park, Valles Caldera National Preserve, and Solfatara Crater, Italy. Our steam collector (Figure 1.1) consists of a stainless shroud with a central holder for the sample tube. The condenser with a splash shield fits into the shroud and is slightly raised at 3 points, allowing excess steam to bypass the edges of the condenser during collection. The central lower guide rod directs condensed steam water into a sterile 50 mL polypropylene tube. During steam collection the open tube rests in a holder attached near the bottom of the shroud. The steam condenser can be handheld, but is also used attached to a tripod by an external mount, which by design serves to protect samples from aerial contaminants. During collection, rising steam contacts the water-cooled condenser and the guide rod drains the condensed steam water directly into the collection tube. After collection, the tube is immediately capped. Overall, the unit is portable, durable, corrosion resistant, easily autoclaved and produces contamination-free steam condensed samples and controls in a relatively short time period. In an average collection a 20–25 mL sample is collected in 15 min. Faster collections occur with a high steam flow rate and elevated temperature. These range between 1–3 mL min-1 in extreme fumaroles near or above 90 °C; examples of those are found in Lassen Volcanic National Park [1.8].
We found that collected steam water carried with it organisms that were detected microscopically when stained with DAPI (a dsDNA stain) and examined by fluorescence microscopy. Ellis et al. [1.8] found organisms in steam from volcanic fumaroles collected at several widely distant geothermal regions: Kamchatka, Russia, Lassen Volcanic National Park, Yellowstone National Park, Sulphur Springs, New Mexico, Valles Caldera National Preserve and Hawai’i Volcanoes National Park. The steam collector was small enough to transport sterile collectors by airplane. The efficiency of collection allowed the collector to be easily used under most field conditions. We were able to estimate cell numbers and found the efficiency of the collector improved with collection from high temperature, low pH steam vents. DAPI staining and phase contrast microscopy showed that steam from all vents examined contained cells. We were able to estimate cell concentrations in steam water, extract DNA for PCR and cloning and isolate Archaea from enrichments and from subcultures. Concentrations ranged from a low value of 150 cells ml-1 in Kamchatka, Russia, to a high number of 1100 cells ml-1 in Lassen Volcanic National Park SW2, a sulfur vent. Microscopic observations revealed that Hawaiian fumaroles contained several morphological types and the greatest diversity of phylotypes of any fumaroles examined. By applying lab collection rates in controlled experiments, we found that the collector efficiency was almost 14%, and the flow rate of one Yellowstone fumarole was determined to be about 15 mL min-1. This allowed us to estimate a dispersal rate of 3 × 103 cells min-1 or 4 × 106 cells day-1. Hawai’i steam samples contained the greatest diversity of halophiles, isolated initially from steam vent water and later from steam deposits, and suggested that halophiles may be present in these habitats though they do not appear able to grow at elevated temperatures [1.8]. This seems to be consistent with other areas enriched with halophiles that may also experience elevated temperatures by insolation.
1.3.2 Steam Deposit Collection
For sampling steam deposit samples when steam caves are too hot for handheld sampling tools, or samples are collected deep within a cave interior, an extension pole is used with a sterile 50 mL polypropylene tube angled up to 45° towards the cave opening. With this approach, only the upper trailing edge of the open tube contacts the deposit matrix. Thus, the steam deposit material removed by the upper collection tube edge falls directly into the open tube, which is capped immediately upon collection. In most fumaroles, collected material is visible and only a few mm (2–4 mm) at the steam-cave surface deposit is removed. Most collection sites have either thick or easily removed deposits of sulfur, salt, iron or other matrix material, making this procedure a relatively easy task. In cases where the steam contact site cannot be seen, the surface is lava, so only a light sampling is carried out, just sufficient to remove the adherent steam deposit material.
Hawai’i presented the greatest variety of chemical types of steam vents. Three of the vents, two coded and one noncoded, were nonsulfur vents. This type of vent is recharged by meteoric input. Rainwater descends through porous ground, contacts rising heat and is converted to steam. Ammonia released by degassing magma creates an ascending mixture of ionized and NH3 gas traveling upward through fissures and fractured lava, reaching passage-ways that lead to horizontal or vertical caves and vents to the atmosphere as fumaroles. In Hawai’i these clouds of rising steam vapors containing volcanic gases and ionized elements support the growth of ammonia oxidizing archaea (AOA) located below the vent opening and adhering to the cave ceilings and walls. Ammonia oxidizing archaea gain their nutrients from entrapped particles, condensing steam and concentrating volcanic gases such as ammonia that rise from closely positioned magma that degases as it rises towards the surface. Altogether these events in the Hawaiian nonsulfur caves support an unusual habitat that thrives on the concentrating effects of surfaces with matrix material and contact between the steam-gas mixture. Here, the cooler cave ceiling or surface condenses steam from the continuous flow of warm thermal vapors and nutrients. Figure 1.2 shows two nonsulfur sites, one in Hawai’i and one in Lassen Volcanic National Park along with a sulfur cave and an iron vent in Lassen, and a salt cave site in Hawai’i Volcanoes National Park. We have documented the presence of AOA in three nonsulfur steam vents in Hawai’i and have recently isolated Archaea-like cultures from the nonsulfur cave and Archaea from the iron vent in Lassen Park. We have not yet determined whether the SW1 nonsulfur cave Archaea-like spheres belong to the Thaumarchaeota, a newly proposed phylum for the ammonia oxidizing archaea [1.4] [1.14] [1.15]. The Hawai’i H1 steam seems similar to the steam at the nonsulfur vent in Lassen Volcanic National Park (Table 1.2) and there is sufficient ammonia at both sites for AOA, and clones were recovered at the Hawai’i H1 site [1.1].
We recognized that a majority of microorganisms growing in natural habitats attach to surfaces. Since there is no sediment in steam caves, organisms tend to attach to the type of surface deposit created by the steam flow and chemical identity of the steam vent or cave (Table 1.1). The chemical features of solid surfaces can be characterized by X-ray microanalysis. As a result, steam deposit samples from caves and vents can be analyzed directly for their chemical composition. In our case, we used an X-max 50 mm2 X-ray detector and a Quanta 450 FEI-SEM operated at 20 kV with Oxford Inca software. Samples were attached with an adhesive-conductive carbon tab to a stub and analyzed. We collected spectra (Figure 1.3) from three different types of caves/vents that supported growth:, (a) Hawai’i H1 nonsulfur cave, (b) Lassen SW1 nonsulfur cave, (c) Lassen SW4 iron vent and Hawai’i H5 salt cave. The salt cave sample remains to be analyzed. The Hawaiian sites H1 and H5 were 65–68 °C and the Lassen sites SW1 and SW4 were 85.5–87 °C.
Figure 1.2 Steam deposit sampling sites: (a) Nonsulfur steam cave site Hawai’i 1, rising steam vapors fill the air to the left of the cave opening (arrow). Ammonia oxidizing archaea (AOA) clones recovered from H1. (b) Nonsulfur steam cave site SW1 Lassen, unknown spherical cell culture recovered and subcultured. (c) Sulfur steam cave SW3 Lassen, steam vapor clouds mix with air and deposit yellow S° inside cave and on outside rock surfaces. Sulfolobus cultures recovered from SW3 and subcultured, pH 4.5, 85 °C. (d) Salt cave site Hawai’i 5, rainwater-lava interaction result in salt cave deposits (white) on the ceiling, wall and floor deep within Hawai’i 5. Mixed culture enrichments, pH 4.5, 55 °C, include abundant unknown thin filaments. (e) Iron steam vent site SW4 Lassen, unknown archaeon recovered and subcultured. (f) Measuring temperature in iron vent SW4 with mercury maximum recording thermometer (arrow). B, E Cultures isolated and subcultured at pH 4.5, 80 °C; SW4 isolate was also subcultured at pH 3, 80 °C. (Image credit: the authors).
Table 1.2 Analysis of steam deposits in Hawai’i and Lassen fumaroles.1
Analyte (mg L
-1
)
H1NS°C
2
SW1NS°C
SW4FeV
3
Na
3.454
3.457
3.453
Ca
2.285
2.119
2.870
Al
1.024
1.258
2.006
Fe (total)
0.975
0.974
0.997
Si
18.579
21.932
25.706
B
0.697
0.723
0.760
K
2.864
3.965
3.401
Mg
0.119
0.138
0.945
Zn
0.0147
0.00455
0.0362
Mn
0.00604
0.00618
0.0256
Mo
0.00
0.00
0.00
Se
0.0289
0.0242
0.0251
Ni
0.00
0.00
0.00
Pb
0.00
0.00
0.00
Cr
0.00
0.00
0.00
Cd
0.00164
0.00178
0.00236
Cu
0.00
0.00
0.00
Hg
0.00
0.00
0.00
As (total)
0.0242
0.0201
0.0209
S
0.0312
5.143
17.833
Sr
0.0832
0.00596
0.0187
NO
2
/NO
3
, N-NO
3
(µM)
0.00
0.00
3.453
NH
4
,N-NH
4
(µM)
19.550
79.023
5.780
PO
4
,P-PO
4
(µM)
0.00
27.372
0.00
SO4 (µM)
0.00
0.00
222.0
Conductivity (µScm
-1
)
13.9
167.2
516
1 Analysis by inductively coupled plasma optical emission spectrometry and wet chemistry.
2 Column 1 Data from Bizzoco and Kelley [1.3].
3 Column 3 data from Bizzoco and Kelley [1.2].
H1NS°C, Hawai’i 1 nonsulfur cave, SW1NS°C Sulphur Works 1 nonsulfur cave, SW4FeV, Sulphur Works 4 iron vent.
The Hawai’i H1 sample (Figure 1.3a) was collected from a hard lava cave ceiling (Figure 1.2a) and contained strong peaks for aluminum (Al), silicon (Si) and iron (Fe). The aluminum peak was also formed by a smaller peak of iridium (Ir). Although characterized as a nonsulfur cave, a small sulfur (S) peak was present in the collected sample and was a characteristic of this cave site. Also observed was a strong peak for oxygen (O) and moderate peaks for titanium (Ti) and several biologically important elements, potassium (K), sodium (Na), magnesium (Mg) and calcium (Ca); each of these peak identities was further documented by analyzing several spectra (data not shown). Titanium has been found along with silicon coated on rock surfaces in the Ka’u desert on the Big Island [1.6] and in most Hawai’i steam cave/vent samples, but titanium has no known role in metabolism. The Lassen nonsulfur cave site SW1 was a shallow cave (Figure 1.2b) composed of soft backing material and the immediate sampling was guided by visual access. There was a distinctive red gelatinous material in the collected sample that proved to be noncellular upon microscopic examination. The nonsulfur SW1 spectrum (Figure 1.3b) had far fewer peaks than the Hawaiian H1 counterpart and contained as its main peaks silicon (Si) and oxygen (O) with smaller peaks for titanium (Ti) and carbon (C). Lassen iron vent SW4 was sampled as a thin (~2–3 mm) soft iron (III) oxide deposit collected from a hard rounded rock surface within the vent (Figure 1.2e, f). The spectrum (Figure 1.3c) contained strong peaks for iron (Fe), silicon (Si), oxygen (O) and aluminum (Al) with a moderate sulfur (S) peak and a smaller carbon (C) peak.
1.3.3 Steam and Steam Deposit Collection: Control Methods
Steam Controls
To control for the presence of foreign DNA in our sample analysis of DNA from steam-condensed samples, we used Millipore filtered (0.22 µm membrane) autoclaved Barnstead purified water. The water was converted to steam next to a cave or vent sampled and collected in identical fashion to steam samples from fumaroles. After collection, samples were analyzed with cave or vent samples by (1) PCR, (2) filtration of 10–15 mL samples on 13 mm black Millipore membranes (0.22 µm pore size) and DAPI microscopy, and (3) for thermophile culture pH 3 and 4.5 at 55, 70, 80, and 85 °C. Control samples proved to be negative.
Steam Deposit Controls
Steam deposit samples from Hawai’i H1 nonsulfur cave were collected by scraping lightly along the inside of the steam cave ceiling. Lava presents a hard surface that cannot be penetrated with a slight 50 mL polypropylene collection tube scraping able to collect steam deposits. We used an adjacent nonfumarolic, ambient temperature lava cave and performed an identical collection procedure with scraping-tube collection used for the steam cave. The other soft surfaces of Lassen nonsulfur cave SW1 and SW2 sulfur cave and Hawai’i H5 salt cave were shallow samplings only a few mm of thick deposits and did not include material other than from the nonsulfur steam deposits, salt deposits or sulfur sublimates. Steam deposit controls were analyzed and evaluated along with the collected steam cave/ vent samples, as described above for PCR, DAPI microscopy and thermophile culture and were negative. We are currently expanding our controls in several ways to evaluate the contribution growing cells might make to the chemical profile from EDX analysis.
Figure 1.3 Steam caves/vents spectra: (a) Hawai’i H1 nonsulfur cave. (b) Lassen nonsulfur cave SW1. (c) Lassen iron vent SW4. (Image credit: the authors).
