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Project Reports

• Biosignatures in Chemosynthetic and Photosynthetic Systems

  Our work examines the microbiology and geochemistry of microbial ecosystems on Earth in order to better understand the production of “biosignatures” — chemical or physical features or patterns that can only have been formed by the activities of life. More specifically, in photosynthetic (light-eating) microbial mats, we examine the factors that control the formation of biosignature gases (such as could be seen by telescope in the atmospheres of planets orbiting other stars) and isotopic and morphological features that could be preserved in the rock record (such as could be examined by rovers on Mars). Additionally, we study the formation of morphological and mineral signatures in chemotrophic (chemical-eating) systems that have no direct access to light or the products of photosynthesis. Such systems likely represent the only viable possibility for extant life on modern day Mars or Europa.

  ROADMAP OBJECTIVES: 2.1 4.1 5.1 5.2 6.1 7.1 7.2

• Biogenic Formation of High-Magnesium Calcite in Sulfide-Rich Systems

  Calcite minerals that contain high proportions of magnsium are well-known biogneic minerals in modern marine environments, reflecting metastable incorporation of Mg in the calcite lattice. In the modern oceans, calcite may form in the presence of sulfide in hydrothermal systems, or, in the ancient Earth, high-magnesium calcite may have formed in the presence of high ambient sulfide (produced by bacterial sulfate reduction or hydrothermal systems), and this project is aimed at understanding the mechamisms involved in producing high-magnesium calcite in the presence of high dissolved sulfide.

  ROADMAP OBJECTIVES: 4.1 6.1 7.1

• Iron Isotope Biosignatures: Laboratory Studies and Modern Environments

  This project seeks to define the biotic and abiotic mechanisms of Fe isotope fractionation in modern sedimentary environments and laboratory model systems. Such information is required to evaluate the potential role of Fe isotopes in understanding the evolution of microbial redox metabolism on the early Earth, and to evaluate their ability to serve as biosignatures of microbial metabolism on other planets (e.g. Mars).

  ROADMAP OBJECTIVES: 4.1 6.1 7.1

• Climate, Habitability, and the Atmosphere on Early Mars

  Atmospheric chemistry has profound implications for the climate and habitability of Mars throughout its history. The presence and stability of greenhouse gases and aerosols, for example, may regulate climate or force climate change. Chemical reactions in the atmosphere initiated by light (“photochemistry”) may also produce gases or aerosols that serve as a shield against ultraviolet light (as stratospheric ozone does on earth) and possibly warm or cool the surface, which, in turn, has implications for the presence and stability of water on Mars. Thus, understanding the chemical composition and physical properties of possible Martian atmospheres over time is vital to the understanding of the opportunities and challenges for early life on Mars, as well as the importance of habitat features that provide radiation protection. In this project, we are investigating in laboratory experiments how quickly photochemistry can destroy and produce various greenhouse gases and aerosols and whether or not the aerosols may serve to warm or cool the surface. We are also investigating whether or not these photochemical reactions can produce carbon-rich aerosols that might be depleted in the stable isotope carbon-13 relative to carbon-12, and thus might be mistaken for an isotopic signature produced by biological processes after the aerosols settle out of the atmosphere and become incorporated into the martian rock record or meteorites that have made it to earth.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 6.1 7.1 7.2

• Erwin Project

  ROADMAP OBJECTIVES: 4.2 6.1

• Iron Oxidation – Shaping the Past and Present Environments

  This year the Edwards Lab completed and published most outstanding results from her NAI projects. Of notable success was the completion of several aspects concerning the abundance and diversity of life on basaltic rocks, including several methods-based studies that examine in detail the biases associated with different approaches used by ourselves, and in other labs as reported in the literature (Santelli et al., 2008; Orcutt et al., in review, Wang and Edwards, in review). The publication by Santelli et al. in Nature resulted in considerable publicity including and NSF press release and associated artists rendition of microbial life on rocks in the deep sea (Fig. 1).

  ROADMAP OBJECTIVES: 6.1

• Evolution of a Habitable Planet (Stewart)

  This project has several foci, including (1) using novel isotope techniques to determine the ages of soils formed very early in Earth’s history; (2) studying the detailed cycling of iron sulfide minerals and the possible isotopic “signatures” of primitive life forms that might be contained within them; (3) tracking the fluxes of dust and salt in extreme Earth environments (the Atacama Desert, Chile) to better understand processes on the surface of Mars.

  ROADMAP OBJECTIVES: 4.1 6.1

• Examination of the Microbial Diversity Found in Ice Cores (Brenchley)

  Our goal is to discover microorganisms surviving in cold or frozen environments and to use this information to understand how different microorganisms survive extreme habitats. Our recent results demonstrated that abundant populations, including many bacteria representing novel taxa, exist frozen in a Greenland glacier ice core for at least 120,000 years. Current isolates are being characterized as new species of ultra-small celled bacteria. This research provides insight into microbial survival in extreme environments that might exist elsewhere in the solar system.

  ROADMAP OBJECTIVES: 2.1 5.1 5.2 5.3 6.1 6.2 7.1

• Pearson Project

  ROADMAP OBJECTIVES: 3.2 4.2 6.1 7.1

• Modeling Early Earth Environments

  In this project, scientists from different disciplines model the conditions likely to have been found on the Early Earth, prior to 2.3 billion years ago. Specific areas of research include understanding the gases, many biologically produced, and mechanisms that controlled early Earth’s surface temperature, the nature of hazes that shielded the planetary surface from UV and may be responsible for signatures in sulfur isotopes that were left in the rock record, the chemical nature of the Earth’s environment during and after a planet-wide glaciation (a “Snowball event”), the evolution of planetary atmospheres over time due to loss of atmosphere to space, and the use of iron isotopes as a tracer of the oxidative state of the Earth’s ocean over time.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 4.1 4.2 5.1 5.2 5.3 6.1 7.2

• Microbial Communities and Activities in the Deep Marine Subsurface

  Novel and unexplored microorganisms thrive in deeply buried marine sediments hundreds of meters below the sea bottom. They extend the domain of life into these energy-starved deep sediments and into the underlying ocean crust. These organisms play essential roles in the microbial cycling of carbon in the deep subsurface. We are exploring their biodiversity, their genetic and physiological repertoire, their role in the ocean ecosystem, and their potential as analogs for extraterrestrial life (see Fig. 1)

  ROADMAP OBJECTIVES: 5.1 5.3 6.1 6.2

• Design, Construction and Testing of a Cavity-Ring Down Spectrometer for Determination of the Concentration and Isotopic Composition of Methane

  The recent detection of CH₄ in the Martian atmosphere and observations suggesting that it varies both temporally and spatially argues for dynamic sources and sinks. CH₄ is a gaseous biomarker on Earth that is readily associated with methanogens when its H and C isotopic composition falls within a certain range. It is imperative that a portable instrument be developed that is capable of measuring the C and H isotopic composition of CH₄ at levels comparable to that on Mars with a precision similar to that of an isotope ratio mass spectrometer and that such an instrument be space flight capable. Such an instrument could guide a rover to a site on Mars where emission of biogenic gases is occurring and samples could be collected for Mars sample return.

  ROADMAP OBJECTIVES: 2.1 2.2 3.3 4.1 5.1 5.2 5.3 6.1 6.2 7.1 7.2

• Hindcasting Ecosystems

  Using the vegetation of South America as an analog to the biosphere of an earth-like planet, this project links Earth Science to Astrobiology. A past-ecosystem-process model was created to predict the history of the carbon cycle in terms of Net Primary Production (NPP). Proxy data were used to reconstruct the past sea surface temperature (SST) of the last 754 years at 1-year resolution. Based upon the high correlation between SST and the vegetation index (NDVI), soil types, potential evapotranspiration, water retention capacity, and nitrogen concentration in soils, the model predicted past NPP for most continental ecosystems of South America.

  ROADMAP OBJECTIVES: 6.1

• Planetary Habitability

  In this research project, members of the VPL team explore different aspects of planetary habitability, and the detectability of habitability and life, using a combination of theoretical models, astronomical observations and Earth-based field work.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 4.1 5.3 6.1 7.2

• Ferry Report

  The research addresses how anaerobic Archaea cope with oxidative stress, with the long-term view of how anaerobic life evolved to adapt to rising oxygen levels before, during and after the evolution of oxygenic photosynthesis. The research also addresses ancient enzymes involved in metabolic pathways with a focus on energy conservation in methanogenic Archaea.

  ROADMAP OBJECTIVES: 3.3 4.1 4.2 5.1 6.1

• DDF: Geomicrobiology of a Unique Ice-Sulfur Spring Ecosystem in the High Arctic

  A glacial, active sulfide spring environment at Borup Fiord Pass on Ellesmere Island in the Canadian High Arctic provides an excellent opportunity to study microbial life at a site that may be an analog to Europa, an ice-covered moon of Jupiter. During the past year we have collected samples from the extensive mats of sulfur-minerals that precipitate in discharge channels to identify the microbial communities hosted in the sulfur-ice, and to cultivate key key organisms mediating the oxidation of H2S to elemental sulfur.

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1 7.1 7.2

• High Lake Gossan Deposit: An Arctic Analogue for Ancient Martian Surficial Processes?

  The massive sulfide deposit at High Lake is covered by a ~1 meter thick layer of Fe oxides and sulfate minerals. The minerals have formed within the last 8,000 years in the active zone of the permafrost and as such the site provides a good analog to those terranes on Mars that contain similar mineral assemblages, e.g. Terra Meridiana, and may have formed under similar, acidic conditions. The minerals present in the High Lake gossan were characterized by XRD, SEM and Mössbauer.

  ROADMAP OBJECTIVES: 2.1 5.1 5.2 5.3 6.1 7.1

• 6. Molecular and Isotopic Biosignatures

  ROADMAP OBJECTIVES: 2.1 3.1 4.1 4.2 5.3 6.1 7.1 7.2

• Iron and Sulfur-Based Biospheres and Their Biosignatures

  This project focuses on the geochemical and microbiological properties of iron (Fe) and sulfur (S) based lithotrophic microbial ecosystems. Recent aspects of this research have been supported by a Director’s Discretionary Fund (DDF) project entitled “Biogeochemical forensics of Fe-based microbial systems: defining mission targets and tactics for life detection on Mars”. The Banfield group is examining Fe concretions at the hypersaline Lake Tyrell in Victoria, Australia as analogs for those which formed at Meridiani Planum on Mars, as well as novel uncultivated, ultra-small Archaea in pyrite oxidation-based microbial communities at Iron Mountain, CA. The latter organisms have only a very small number of ribosomes per cell (ca. 92, compared to ca. 10,000 for E. coli in culture), which are positioned around the inside of the inner membrane. The size and highly organized internal structure of these organisms provide clues to the strategies of life at its lower size limits. The Emerson group is investigating natural populations and pure cultures of Fe(II)-oxidizing bacteria in an attempt to better understand how their physiology and ecology influences the mineralogy and geochemistry that are hallmarks of these organisms in the environment. A major focus of this work, in collaboration with the Luther group, has been to gain a better understanding the contribution that neutrophilic, oxygen-dependent Fe(II)-oxidizing bacteria make to Fe(II) oxidation kinetics both in situ and in the laboratory. Additional work has focused on the ultrastructure and behavior of a unique Fe-oxidizing bacterium, Mariprofundus ferrooxydans, isolated from a deep-sea hydrothermal vent that had extensive mats of Fe(II)-oxidizing bacteria. The Luther group has been examining a variety of environments where microbially-driven Fe(II) oxidation occurs, including areas where free sulfide is not present (creeks in VA and Chocolate Pots, Yellowstone National Park) and locations where free sulfide is present [local Delaware Inland Bays and the hydrothermal vents at Kilo-Moana (20°3’S, 176°8’W), located on the East Lau Spreading Centre (ELSC), in the Lau Basin, SW Pacific Ocean]. These studies demonstrate that it is possible to distinguish between abiotic and biotic mechanisms for Fe(II) oxidation using real time measurements. Roden’s group has examined microbial communities and biosignatures in several different Fe-dominated natural systems, including circumneutral pH groundwater Fe seeps in Tuscaloosa, AL; a Pliocene-age weathered volcanic tuff unit in Box Canyon, ID; hypersaline Lake Tyrell; and chemically-precipitated sediments in the Spring Creek Arm of the Keswick Reservoir downstream of the Iron Mountain acid mine drainage site in northern CA. We have also evaluated the composition and function of an anaerobic, nitrate-dependent Fe(II)-oxidizing enrichment culture which is capable of chemolithoautotrophic growth coupled to oxidation of the insoluble ferrous iron-bearing phyllosilicate mineral biotite.

  ROADMAP OBJECTIVES: 4.1 6.1 7.1 7.2

• Planetary-Scale Transition From Abiotic to Biotic Nitrogen Cycle

  Nitrogen is an essential element for life. Understanding the planetary nitrogen cycle is critical to understanding the origin and evolution of life. The earth’s atmosphere is full of nitrogen gas (N2). However, this large pool of nitrogen is unavailable to most of the life on earth except a few microbes capable of “fixing” nitrogen into a form that can be used by other organisms (e.g., NH3, NH4+, NOx, organic-N). Without fixed nitrogen life would not have originated on earth and would most likely not occur on any other planet. The Atacama Desert in Chile is an enigma in that it contains vast nitrate (a type of fixed nitrogen) deposits. Elsewhere on earth, nitrate is either denitrified (transformed into N2 and released back into the atmosphere) through the activity of microorganisms, or is dissolved and leached from the system. Although the Atacama is the driest desert in the world we have shown that lack of water alone cannot account for the lack of nitrogen cycling in this desert. Preliminary data suggest that it may be due to the high oxidation level of the soil in combination with a lack of organic material in the soil.

  ROADMAP OBJECTIVES: 1.1 2.1 3.2 4.1 5.1 5.2 5.3 6.1

• Planetary Surface and Interior Models and Super Earths

  In this task we are developing and using models of a terrestrial planet’s surface and interior to understand
  the evolution of planetary environments. These models allow us to understand how interactions between the
  planetary surface and interior, and life, affect a planet’s atmosphere. New models are also exploring the possible habitability of “super-Earths”, rocky planets that have been found around other stars that can be up to 10 times more massive than our own Earth.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 5.2 6.1 7.2

• Identifying Microbial Life at Crustal Rock-Water Interfaces

  We are working to cultivate and characterize microorganisms which directly derive energy from reactions between mafic rocks and water. We are particularly targeting organisms that colonize the surfaces of the rocks during alteration. Thus we are also developing high-resolution chemical measurements capable of detecting reaction fronts and mineral by-products that form over time at the microbe-mineral interface.

  ROADMAP OBJECTIVES: 5.2 5.3 6.1 6.2 7.2

• Isotopic Signatures of Methane and Higher Hydrocarbon Gases From Precambrian Shield Sites: A Model for Abiogenic Polymerization of Hydrocarbons

  Methane and higher hydrocarbon gases in ancient rocks on Earth originate from both biogenic and abiogenic processes. The measured carbon isotopic compositions of these natural gases are consistent with formation of polymerization of increasing long hydrocarbon chains starting with methane. Integration of carbon isotopic compositions with concentration data is needed to delineate the origin of hydrocarbon gases.

  ROADMAP OBJECTIVES: 1.1 2.1 3.1 4.1 4.2 6.1 7.1 7.2

• Mars Forward Contamination Studies Utilizing a Mars Environmental Simulation Chamber

  A variety of microorganisms have been selected for experimental culturing in a Mars environmental simulation chamber. The test organisms are adapted on Earth to desiccation resistance and cold tolerance so they are suitable for exposure to simulated surface conditions on Mars. The test chamber is capable of reproducing temperatures, solar radiation, and atmospheric conditions inferred for Mars. Results from these tests will provide critical information for the design and engineering of sampling and caching equipment on a future mission to sample rocks and sediments on Mars and return those samples to Earth for laboratory study.

  ROADMAP OBJECTIVES: 2.1 3.2 3.3 5.1 5.2 5.3 6.1 6.2 7.1

• The High Lakes Project (HLP)

  The High Lakes Project is a multi-disciplinary astrobiological investigation studying high-altitude lakes between 4,200 m and 5,916 m elevation in the Central Andes of Bolivia and Chile. Its primary objective is to understand the impact of increased environmental stress on lake habitats and their evolution during rapid climate change as an analogy to early Mars. Their unique geophysical environment and mostly uncharted ecosystems have added new objectives to the project, including the assessment of the impact of low ozone/high solar irradiance in non-polar aquatic environments, the documentation of poorly known ecosystems, and the quantification of the impact of climate change on lake environment and ecosystem.
  Data from 2003 to 2007 show that solar irradiance is 165% that of sea level with instantaneous UV-B flux reaching 17W/m2. Short UV wavelengths (260-270 nm) were recorded and peaked at 14.6 mW/m2. High solar irradiance occurs in an atmosphere permanently depleted in ozone falling below ozone hole definition for 33-36 days and between 30-35% depletion the rest of the year. The impact of strong UV-B and UV erythemally-weighted daily dose on life is compounded by broad daily temperature variations with sudden and sharp fluctuations. Lake habitat chemistry is highly dynamical with notable changes in yearly ion concentrations and pH resulting from low and variable yearly precipitation. The year-round combination of environmental variables define these lakes as end-members. In such an environment, they host surprisingly abundant and diverse ecosystems including a significant fraction of previously undescribed species of zooplankton, cyanobacterial, and bacterial populations.

  ROADMAP OBJECTIVES: 1.1 2.1 4.1 4.3 5.1 5.2 5.3 6.1 6.2 7.1

• The Virtual Planetary Laboratory – The Life Modules – Photosynthesis

  Photosynthesis provides the foundation for nearly all life on our planet and produces unique life signs — atmospheric oxygen and pigment colors — that are detectable from space at the global scale. This project seeks to determine the adapative rules for why photosynthetic pigments absorb particular wavelengths of light, and to quantify what is the long wavelength limit for oxygenic and also anoxygenic photosynthesis. This work will allow us to predict the plausible spectral properties and detectable properties of photosynthesis on other planets, especially those orbiting M stars, where longer wavelengths of light dominate the planetary surface radiation.

  ROADMAP OBJECTIVES: 5.1 6.1 6.2 7.2

• Untitled

  We are exploring the geological and geochemical record of ancient Earth for clues about the co-evolution of life and environment. We’re focusing on three events in Earth history: the apparent rise of atmospheric oxygen at 2.45 billion years ago, the establishment of life on land during the Cambrian (about 540 milliion years ago), and the greatest mass extinction of all time at the end of the Permian, 252 million years ago. We use a combination of computer modeling, field work, and laboratory analysis.

  ROADMAP OBJECTIVES: 4.1 6.1 7.1 7.2

• Sulfur Biogeochemistry of the Early Earth

  Sulfur is widespread in surface geochemical systems and is abundant in many rock types. It is present in volcanic gases and marine waters, and has served a key role in geobiological processes since the origin of life. Like other low atomic number elements, sulfur isotope ratios in various compounds usually follow predictable mass-dependent fractionation laws; these different mass-dependent isotope fractionations serve as powerful tracers for igneous, metamorphic, sedimentary, hydrothermal and biological processes. Mass-independent sulfur isotope fractionation is a short-wavelength photolytic effect that occurs in space, as well as in gas-phase reactions in atmospheres transparent to deep penetration by ultraviolet light. Crucial aspects of the chemical evolution of the early atmosphere — and the surface zone as a whole — can be followed by mass-independent sulfur isotopes in Archean metasedimentary rocks. Metabolic styles of organisms in response to global changes in surface redox over geologic time can also be traced with multiple S isotopes.

  We have concluded from our various studies over the last year and before to the very inception of the NAI node at Colorado, that all Archean sulfur minerals previously documented for their 34S/32S compositions warrant a comprehensive re-examination of their 32S, 33S, 34S (and 36S), sulfur isotope systematics.

  ROADMAP OBJECTIVES: 1.1 1.2 4.1 4.2 5.1 5.2 5.3 6.1 7.1 7.2

• Ecology of a Hawaiian Lava Cave Microbial Mat

  We have been studying a microbial biofilm (Figure 1) growing at very low light intensities and high temperature and humidity below the entrance of a lava cave in Kilauea Crater, Hawai’i Volcanoes National Park. (Figure 2)
  The cave presents an oligotrophic environment, but condensation of geothermally heated groundwater that vents at the rear of the cave has promoted the development of a complex microbial community, similar in higher order taxonomic structure to copiotrophic soil environments. Given the existence of lava tubes of similar geologic composition on Mars, geothermal activity there may have allowed the existence, or persistence, of complex microbial communities in similar Martian environments, wherein they would be shielded from the effects of harmful UV radiation.

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1

• Mechanisms of Marine Microbial Community Structuring

  The sub-tropical open ocean is an extreme environment that presents the opportunity to examine the factors affecting microbial community structure across a number of environmental gradients. We have developed and utilized a novel assay that allows us to simultaneously determine the taxonomic composition of Archaea, Bacteria and microbial Eucarya in DNA extracted from environmental samples. Samples analyzed represent the epi-, meso- and bathy-pelagic zones of the ocean, which display gradients in temperature, pressure, oxygen content, nutrient content and photosynthetically available radiation.

  ROADMAP OBJECTIVES: 5.1 5.2 5.3 6.1

• Sediment-Buried Basement Deep Biosphere

  There is growing evidence that a substantial subseafloor biosphere extends throughout the immense volume of aging basement (basaltic rock) of the ocean crust. Since most ocean basement rock is buried under thick, impermeable layers of sediment, the fluids circulating within the underlying ocean basement are usually inaccessible for direct studies. Circulation Obviation Retrofit Kit (CORK) observatories affixed to Integrated Ocean Drilling Program (IODP) boreholes offer an unprecedented opportunity to study biogeochemical properties and microbial diversity in circulating fluids from deep ocean basement. UH-NAI post doctoral fellows (e.g., Brian Glazer, Andrew Boal)

  ROADMAP OBJECTIVES: 1.1 3.3 4.1 5.1 5.2 5.3 6.1 6.2