nai

Project Reports

• Biomimetic Cluster Synthesis: Bridging the Structure and Reactivity of Biotic and Abiotic Iron-Sulfur Motifs

  Synthetic approaches are being utilized to bridge the gap between Fe-S minerals and highly evolved biological Fe-S metalloenzymes. These studies are focusing on organic template (protein) mediated cluster assembly (biomineralization), probing properties of synthetic clusters, both as homogeneous and heterogeneous catalysts, investigating the impact of size scale on the properties of synthetic Fe-S clusters, and computational modeling of the structure and catalytic properties of synthetic Fe-S nanoparticles in the 5-50 nm range.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 7.2

• Computational Chemical Modeling the Link Between Structure and Reactivity of Iron-Sulfur Motifs

  The Fe-S mineral catalysis, Fe-S enzyme catalysis, and a biomimetic thrust areas of ABRC have their own unique ways to probe the relationships between structure and reactivity at the active sites of iron-sulfur enzymes and the structure and reactivity of iron-sulfur minerals. We have developed a cohesive link among these thrust areas through bridging the enzymatic/mineral catalysis and molecular structure/chemical reactivity by computational chemistry.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Molecular Beam Studies of Nitrogen Reactions on Iron-Sulfur Surfaces

  It is generally accepted that surface-mediated reactions occur on defect sites. The role of defects in the formation of ammonia is being evaluated using molecular beam-surface scattering experiments in which a deuterium atom plasma source is used to hydrogenate a pyrite surface with D atoms. The hydrogenated surface is subsequently bombarded with a molecular beam of energetic N2 molecules and the conversion of N2 to products such as ammonia is probed through mass spectrometry.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 7.1 7.2

• Origin of Life and Catalysis – Philosophical Considerations

  Our goal is to provide a solid philosophical foundation for the ABRC research program. To achieve this goal, we have several sub-goals like helping the students to develop their position as a group regarding a viable account for the metabolism-first theory, examining some methodological assumptions of the current astrobiological community, and finally propagating the information learned in our group to a larger community by offering courses on the origin of life.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.2

• 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

• Probing the Structure and Nitrogen Reduction Activity of Iron-Sulfur Minerals

  Fe-S compounds are common in both biological and geological systems. The adaptation of Fe-S clusters from the abiotic world to the biological world may have been an early event in the development of life on Earth and possibly a common feature of life elsewhere in the universe. The Iron-sulfur mineral thrust of the ABRC is focused on examining the structure and reactivity of FeS minerals using nitrogen fixation as a model reaction.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 7.1 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

• Microbial Diversity and Population Structure Studies in the Rio Tinto

  As part of our Microbial diversity and population structure studies in the Rio Tinto, we hope to better understand how environmental conditions such as pH and metal concentrations help shape the underlying microbial community structures in extreme environments that serve as terrestrial analogs for Mars. The iron-based mineralogy found in the Rio Tinto coupled with low pH are two characteristics that tie this extreme environment to Mars. To this end, we have been sampling stations along the river that differ in the concentration and oxidation state of iron and other metals (see http://amarallab.mbl.edu/rt_main/rt.html for more detailed information and photographs of the study locations) and using molecular techniques coupled with physicochemical measurements to investigate microbial diversity in the water column at both spatial and temporal scales. When possible, determination of as many in situ physico-chemical parameters are made on biofilms as well, using microelectrodes available for field measurements. This allows for the correlation of biological diversity information with physicochemical parameters of the river. The outcome of this study will provide a comprehensive view of the microbial ecology of the system, a first step towards establishing an ecological genomics project for the Rio Tinto.

  ROADMAP OBJECTIVES: 3.3 5.1 5.2

• Structure, Function, and Biosynthesis of the Complex Iron-Sulfur Clusters at the Active Sites of Nitrogenases and Hydrogenases

  Iron-sulfur clusters are thought to be among the most ancient cofactors in living systems. The Fe-S enzyme thrust is focused on examining the structure, mechanism, and biosynthesis of the complex Fe-S enzymes nitrogenase and hydrogenase.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 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

• Microbial Diversity of a Hypersaline Microbial Mat

  The goal of this project is to survey the microbial life that comprises a hypersaline microbial mat at Guerrero Negro, Mexico using culture independent technology (ribosomal and other gene sequences). The results have expanded significantly our knowledge of microbial diversity, bacterial, archaeal and eucaryotic.

  ROADMAP OBJECTIVES: 3.2 3.3 5.1 5.2 5.3 7.2

• Philosophical Problems in Astrobiology; Issues on the Origin of Life,

  My project is exploring philosophical issues in astrobiology. My central focus this year was on the origin of life: what is the proper level of analysis for a successful theory of the origin of life? Among other things, I compared and contrasted contemporary scientific theories of the origin of life in light of what philosophers of science have learned about the structure and justification of scientific theories.

  ROADMAP OBJECTIVES: 3.1 3.2 3.3 3.4 4.1 4.2

• Radiolytic Oxidation of Sulfide Minerals as a Source of Sulfate and Hydrogen to Sustain Microbial Metabolism

  Microbial ecosystems have been discovered in crustal environments up to 2.8 kilometers below the surface of Earth. Life in this extreme environment apapears to be sustained by high concentrations of dissolved sulfate and hydrogen. Splitting of water molecules by radiation from uranium can produce oxidation gradients that result in simple ionic products usable for maintenance and growth of microbial organisms. A set of experiments exposing water and common sulfide minerals to radiation in a laboratory reactor were conducted to test this hypothesis.

  ROADMAP OBJECTIVES: 1.1 2.1 3.3 4.1 5.1 5.3 6.2

• 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