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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Extended Survival of Several Microorganisms and Relevant Amino Acid Biomarkers under Simulated Martian Surface Conditions as a Function of Burial Depth

Recent orbital and landed missions have provided substantial evidence for ancient liquid water on the martian surface as well as evidence of more recent sedimentary deposits formed by water and/or ice. These observations raise serious questions regarding an independent origin and evolution of life on Mars. Future missions seek to identify signs of extinct martian biota in the form of biomarkers or morphological characteristics, but the inherent danger of spacecraft-borne terrestrial life makes the possibility of forward contamination a serious threat not only to the life detection experiments, but also to any extant martian ecosystem. A variety of cold and desiccation-tolerant organisms were exposed to 40 days of simulated martian surface conditions while embedded within several centimeters of regolith simulant in order to ascertain the plausibility of such organisms survival as a function of environmental parameters and burial depth. Relevant amino acid biomarkers associated with terrestrial life were also analyzed in order to understand the feasibility of detecting chemical evidence for previous biological activity. Results indicate that stresses due to desiccation and oxidation were the primary deterrent to organism survival, and that the effects of UV-associated damage, diurnal temperature variations, and reactive atmospheric species were minimal. Organisms with resistance to desiccation and radiation environments showed increased levels of survival after the experiment compared to organisms characterized as psychrotolerant. Amino acid analysis indicated the presence of an oxidation mechanism that migrated downward through the samples during the course of the experiment and likely represents the formation of various oxidizing species at mineral surfaces as water vapor diffused through the regolith. Current sterilization protocols may specifically select for organisms best adapted to survival at the martian surface, namely species that show tolerance to radical-induced oxidative damage and low water activity environments. Additionally, any hypothetical martian ecosystems may have evolved similar physiological traits that allow sporadic metabolism during periods of increased water activity.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2012

Microbial metaproteomics: Identifying the repertoire of proteins that microorganisms use to compete and cooperate in complex environmental communities

The availability of genome information for microbial consortia, including unculturable species, from environmental samples has enabled systems-biology interrogation by providing a means to access genomic, transcriptomic, and proteomic information. This provides a unique opportunity to characterize the molecular activities and interactions of these microbial systems at a comprehensive level never before possible. Such information not only provides details about the organizational, functional, and metabolic activities of such systems, but also the untapped reserve of molecular activities that might be invoked and exploited under certain environmental conditions. Since bacteria naturally exist in complex ecosystems, it is imperative to develop and utilize analytical approaches that can provide molecular level details on systems consisting of mixed microbial membership. This is the realm of metaproteomics - the characterization of the complement of proteins expressed by a microbial community in an environmental sample

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1962

RESEARCH TO DETERMINE THE EXISTENCE AND IDENTITY OF VIABLE MICROORGANISMS IN THE STRATOSPHERE.

During January, February, and March significant progress was made in our attempt to conduct a microbiological exploration of the atmosphere. The microbiological, engineering, meteorological, and statistical problems relative to this exploration were defined, and many preliminary laboratory studies completed, An integrated approach to the study was agreed upon and a schedule outlined. According to this schedule, the first flight will be made during July and the second probe will be attempted in October.

VIABILITY↗
DOE OSTI2010

Influence of microorganisms on the oxidation state distribution of multivalent actinides under anoxic conditions

The fate and potential mobility of multivalent actinides in the subsurface is receiving increased attention as the DOE looks to cleanup the many legacy nuclear waste sites and associated subsurface contamination. Plutonium, uranium and neptunium are the near-surface multivalent contaminants of concern and are also key contaminants for the deep geologic disposal of nuclear waste. Their mobility is highly dependent on their redox distribution at their contamination source as well as along their potential migration pathways. This redox distribution is often controlled, especially in the near-surface where organic/inorganic contaminants often coexist, by the direct and indirect effects of microbial activity. Under anoxic conditions, indirect and direct bioreduction mechanisms exist that promote the prevalence of lower-valent species for multivalent actinides. Oxidation-state-specific biosorption is also an important consideration for long-term migration and can influence oxidation state distribution. Results of ongoing studies to explore and establish the oxidation-state specific interactions of soil bacteria (metal reducers and sulfate reducers) as well as halo-tolerant bacteria and Archaea for uranium, neptunium and plutonium will be presented. Enzymatic reduction is a key process in the bioreduction of plutonium and uranium, but co-enzymatic processes predominate in neptunium systems. Strong sorptive interactions can occur for most actinide oxidation states but are likely a factor in the stabilization of lower-valent species when more than one oxidation state can persist under anaerobic microbiologically-active conditions. These results for microbiologically active systems are interpreted in the context of their overall importance in defining the potential migration of multivalent actinides in the subsurface.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2011

Genomic and Expression Analyses of Cold-Adapted Microorganisms.

Contents 7.1 Introduction 7.2 Ecological evidence of bacterial adaptation to cold 7.2.1 Characteristics of cold environments and implications for microbial ecology 7.2.2 Ecological adaptation in Exiguobacterium spp. and Psychrobacter spp. 7.3 Gene Expression Responses to the Cold 7.3.1 Fundamentals of Gene Expression Responses to Cold 7.3.2 Acclimation for Life in Cold Habitats 7.3.2.1 Translation and Chaperone Proteins: Safeguarding the functional units of cellular physiology 7.3.2.2 Carbon and Energy metabolism: resource efficiency over long generation times 7.3.2.3 Amino Acid Biosynthesis: Species-specific responses to species-specific deficiencies 7.3.2.4 Compatible solutes: a concomitant response in cryoenvironments 7.3.2.5 Membrane fluidity: A major role in the overall metabolic rate at temperature 7.3.2.6 The cell wall at low temperature: A poorly understood growth rate determinant 7.3.2.7 Transporters: The balance between local nutrient uptake and depletion 7.3.2.8 Genome plasticity. The potential role of transposases and repeated sequences. 7.4 Protein adaptations to cold 7.4.1 The low temperature challenge 7.4.2 The stability activity relationship 7.4.3 Structural features of cold adapted enzymes. 7.4.4 Hydrophobic interactions 7.4.5 Electrostatic interactions 7.4.5.1 Arginine 7.4.5.2 Acidic residues 7.4.6 Structural elements 7.4.6.1 -helices and -sheets 7.4.6.2 Proline and Glycine 7.4.6.3 Disordered regions 7.5 Comparison of cold- and warm-adapted Exiguobacterium strains 7.5.1 Phylogeny reflects adaptations to environmental conditions 7.5.2 Genomic comparison of two strains 7.6 Summary and future directions

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Remediation of Irradiated Graphite Using Microorganisms Isolated from Oil Contaminated Soil - 19643

The deployment of nuclear energy globally is hindered by the fear cleared by nuclear reactor disasters such as the Chernobyl and Fukushima reactor meltdowns. Additionally, accumulation of radioactive waste globally will, in the near future, present a significant threat to humans and the environment. Notably, the majority of nuclear waste from the energy generation industry is generated as Low Level Waste (LLW) in which the small radioactive component renders the bulk of the waste unsuitable for conventional treatment and disposal. In the case of radioactive graphite, the small radioactive component comprising radiocarbon-14 (C-14) and metallic pollutants can be removed to allow safe disposal or reuse as of the graphite. In the current study, mixed-cultures of organisms isolated from oil contaminated sites showed potential of selective bioaccumulation of C-14 from a powdered C-12/C-14 graphite matrix. The study was conducted in a continuously mixed reactor (growth vessel) constructed from Pyrex panels (30 cm x 20 cm x 15 cm) with finely ground graphite as the principal carbon source (1500-2000 mg.L{sup -1}) and spikes of glucose (500 mg.L{sup -1} every 48 hours). The growth vessel was connected to a biofilter unit by submersible pump where particulate matter was isolated for further analysis. Results showed that approximately 68% more C-14 was released from ignited dry cells than from respiration product. C-14 accumulated in cells corrected using a trap filter system, with a marked decrease of C-14 in carbon dioxide than vegetative suspended cells in the main tank. The only mechanism that could account for the differential C-14 distribution between the liquid medium and cells was possible fractionation during uptake of carbon compounds. The discriminating factor suggested in this study is the kinetic isotope effect (KIE) which allows heavier atoms to have different affinities for reaction sites on catalysis and biocatalysis. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

Rapid quantification of alcohol production in microorganisms based on nanostructure-initiator mass spectrometry (NIMS)

We described a mass spectrometry-based assay to rapidly quantify the production of primary alcohols directly from cell cultures. This novel assay used the combination of TEMPO-based oxidation chemistry and oxime ligation, followed by product analysis based on Nanostructure-Initiator Mass Spectrometry. This assay enables quantitative monitor both C5 to C18 alcohols as well as glucose and gluconate in the growth medium to support strain characterization and optimization. We find that this assay yields similar results to gas chromatography for isoprenol production but required much less acquisition time per sample. We applied this assay to gain new insights into P. Putida's utilization of alcohols and find that this strain largely could not grow on heptanol and octanol.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗