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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

The occurrence of denitrification in extremely halophilic bacteria

The ability of Halobacterium vallismortis, Halobacterium mediterranei and Halobacterium marismortui (Ginzburg strain) to grow anaerobically and denitrify was determined. Each organism grew anaerobically only in the presence of nitrate. H. marismortui produced nitrite and dinitrogen from nitrate during exponential growth. However, as the culture entered stationary phase, dinitrogen production ceased and nitrous oxide was detected. H. vallismortis produced nitrous oxide and dinitrogen during exponential growth, with dinitrogen production ceasing at the onset of stationary phase. H. mediterranei produced dinitrogen during exponential growth and did not produce nitrous oxide. These results confirm the occurrence of denitrification in the halobacteria.

Mancinelli, R. L.↗
NASA NTRS1990

Survival of pathogenic bacteria under nutrient starvation conditions

The survival of opportunistic pathogenic microorganisms in water, under nutrient-limiting conditions, has been investigated in order to ascertain whether human pathogens can survive within a water-distribution system of the kind proposed for the NASA Space Station. Cultures of a strain of pseudomonas aeruginosa and two strains of staphylococcus aureus were incubated at 10, 25, or 37 C, and samples at 1 day, 1 week, 1 month, and six weeks. While neither of the staphylococcus strains tested were detected after 1 week of starvation, the pseudomonas strain can survive in deionized water at all three temperatures.

Boyle, Michael↗
NASA NTRS1993

Optimization of 15 parameters influencing the long-term survival of bacteria in aquatic systems

NASA is presently engaged in the design and development of a water reclamation system for the future space station. A major concern in processing water is the control of microbial contamination. As a means of developing an optimal microbial control strategy, studies were undertaken to determine the type and amount of contamination which could be expected in these systems under a variety of changing environmental conditions. A laboratory-based Taguchi optimization experiment was conducted to determine the ideal settings for 15 parameters which influence the survival of six bacterial species in aquatic systems. The experiment demonstrated that the bacterial survival period could be decreased significantly by optimizing environmental conditions.

Obenhuber, D. C.↗
NASA NTRS1993

Stable isotopes as tracers of methane dynamics in Everglades marshes with and without active populations of methane oxidizing bacteria

The stable carbon isotopic composition of CH4 is used to study the processes that affect it during transport through plants from sediment to the atmosphere. The enhancement of CH4 flux from Cladium and Eleocharis over the flux from open water or clipped sites indicated that these plants served as gas conduits between the sediments and the atmosphere. Lowering of the water table below the sediment surface caused an Everglades sawgrass marsh to shift from emission of CH4 to consumption of atmospheric CH4. Cladium transported gases passively mainly via molecular diffusion and/or effusion instead of actively via bulk flow. Stable isotropic data gave no evidence that CH4 oxidation was occurring in the rhizosphere of Cladium. Both CH4 stable carbon isotope and flux data indicated a lack of CH4 oxidation at the sediment-water interface in Everglades marl soils and its presence in peat soils where 40 to 92 percent of the flux across the sediment-water interface was oxidized.

Happell, James D.↗
NASA NTRS1997

Workshop on Viability of Halophilic Bacteria in Salt Deposits

The significance of finding viable extreme halophiles in halites associated with Permian-aged sedimentary deposits is considered. Issues related to the microbiology and geochemistry of the halite environment are addressed. Recommendations that related the significance of this phenomenon to NASA's interest in planetary exploration and the early evolution of life are provided.

Source record↗
NASA NTRS1998

An Advanced Approach to Simultaneous Monitoring of Multiple Bacteria in Space

The utility of a novel microarray-based microbial analyzer was demonstrated by the rapid detection, imaging, and identification of a mixture of microorganisms found in a waste water sample from the Lunar-Mars Life Support Test Project through the synergistic combination of: (1) judicious RNA probe selection via algorithms developed by University of Houston scientists; (2) tuned surface chemistries developed by Baylor College of Medicine scientists to facilitate hybridization of rRNA targets to DNA probes under very low salt conditions, thereby minimizing secondary structure; and (3) integration of the microarray printing and detection/imaging instrumentation by Genometrix to complete the quantitative analysis of microorganism mixtures.

Eggers, M.↗
NASA NTRS1998

An Advanced Approach to Simultaneous Monitoring of Multiple Bacteria in Space

This interim report describes progress on the development of spacecraft-compatible methods of nucleic acid preparation and cleanup. Grantee found that performance of a widely-known protocol could be greatly enhanced by the addition of a sizing step to eliminate acids. Testing of alternative adsorptive methods is underway. Grantee also confirmed and extended observation of precipitation of DNA by condensing agents such a spermine at low ionic strength.

Eggers, Mitch↗
NASA NTRS1998

Mineralization of Bacteria in Terrestrial Basaltic Rocks: Comparison With Possible Biogenic Features in Martian Meteorite Allan Hills 84001

The identification of biogenic features altered by diagenesis or mineralization is important in determining whether specific features in terrestrial rocks and in meteorites may have a biogenic origin. Unfortunately, few studies have addressed the formation of biogenic features in igneous rocks, which may be important to these phenomena, including the controversy over possible biogenic features in basaltic martian meteorite ALH84001. To explore the presence of biogenic features in igneous rocks, we examined microcosms growing in basaltic small-scale experimental growth chambers or microcosms. Microbial communities were harvested from aquifers of the Columbia River Basalt (CRB) group and grown in a microcosm containing unweathered basalt chips and groundwater (technique described in. These microcosms simulated natural growth conditions in the deep subsurface of the CRB, which should be a good terrestrial analog for any putative martian subsurface ecosystem that may have once included ALH84001. Here we present new size measurements and photomicrographs comparing the putative martian fossils to biogenic material in the CRB microcosms. The range of size and shapes of the biogenic features on the CRB microcosm chips overlaps with and is similar to those on ALH84001 chips. Although this present work does not provide evidence for the biogenicity of ALH84001 features, we believe that, based on criteria of size, shape, and general morphology, a biogenic interpretation for the ALH84001 features remains plausible.

Thomas-Keprta, K. L.↗
NASA NTRS1999

Looking for Fossil Bacteria in Martian Materials

The rationale for looking for prokaryote fossils in Martian materials is based on our present understanding of the environmental evolution of that planet in comparison to the history of the terrestrial environments and the development and evolution of life on Earth. On Earth we have clear, albeit indirect, evidence of life in 3.8 b.y.-old rocks from Greenland and the first morphological fossils in 3.3-3.5 b.y.-old cherts from South Africa and Australia. In comparison, Mars, being smaller, probably cooled down after initial aggregation faster than the Earth. Consequently, there could have been liquid water on its surface earlier than on Earth. With a similar exogenous and endogenous input of organics and life-sustaining nutrients as is proposed for the Earth, life could have arisen on that planet, possibly slightly earlier dm it did on Earth. Whereas on Earth liquid water has remained at the surface of the planet since about 4.4 b.y. (with some possible interregnums caused by planet-sterilising impacts before 3.8. b.y. and perhaps a number of periods of a totally frozen Earth, this was not the case with Mars. Although it is not known exactly when surficial water disappeared from the surface, there would have been sufficient time for life to have developed into something similar to the terrestrial prokaryote stage. However, given the earlier environmental deterioration, it is unlikely that it evolved into the eukaryote stage and even evolution of oxygenic photosynthesis may not have been reached. Thus, the impetus of research is on single celled life simnilar to prokaryotes. We are investigating a number of methods of trace element analysis with respect to the Early Archaean microbial fossils. Preliminary neutron activation analysis of carbonaceous layers in the Early Archaean cherts from South Africa and Australia shows some partitioning of elements such as As, Sb, Cr with an especial enrichment of lanthanides in a carbonaceous-rich banded iron sediment . More significantly, preliminary TOF-SIMS investigations of organics in the cherts reveals the presence of a biomarker, which appears to be a derivative of bacterial polymer, in the carbonaceous parts of the rocks. We conclude that a combination of morphological, isotope and biogeochemical methods can be used to successfully identify signs of life in terrestrial material, and that these methods will be useful in searching for signs of life in extraterrestrial materials.

Westall, F.↗
NASA NTRS1999

Possible Bacteria in Nakhla

Mars Agueous Alteration Nakhla contains alteration products in an extensive network of which fill cracks, veins, and void spaces, composed of smectite, although in some cases they are amorphous and gel-like. Strong evidence presented show that these alteration products developed on Mars: some veins are offset by impact faulting of olivine followed by annealing of the olivine, and veins near the fusion crust show partial vesicle development suggesting heating and volatile liberation. The smectite-containing cracks and veins are interpreted as low temperature aqueous alteration on Mars. We have been studying these veins with optical microscopy and high resolution SEM.

McKay, David S., Jr.↗
NASA NTRS1999

Identifying Fossil Bacteria in Martian Materials

Within the next decade, robotic missions are going to Mars with the search for evidence for extant and extinct life as at least one of the mission objectives. Moreover, the first Martian samples will be returned to Earth in 2008. It is therefore imperative that we can be certain that we can identify life in Martian rocks. In this paper we will not be discussing extant life but will concentrate on fossil life.

Westall, F.↗
NASA NTRS1998

Beating Back Bacteria

Under a NASA-Johnson Space Center contract, Umpqua Research developed the MCV (Trademark) (Microbial Check Valve) which uses iodinated ion exchange resin used for water purification systems aboard space missions. Using this resin, MRLB International, Inc., developed and commercialized the Dentapure purification cartridge used by dentists nationwide.

Source record↗
NASA NTRS2001

Detecting Pyrolysis Products from Bacteria on Mars

A pyrolysis/sublimation technique was developed to isolate volatile amine compounds from a Mars soil analogue inoculated with approx. 10 billion Escherichia coli cells. In this technique, the inoculated soil is heated to 500 C for several seconds at Martian ambient pressure and the sublimate, collected by a cold finger, then analyzed using high performance liquid chromatography. Methylamine and ethylamine, produced from glycine and alanine decarboxylation, were the most abundant amine compounds detected after pyrolysis of the cells. A heating cycle similar to that utilized in our experiment was also used to release organic compounds from the Martian soil in the 1976 Viking gas chromatography/mass spectrometry (GC/MS) pyrolysis experiment. The Viking GC/MS did not detect any organic compounds of Martian origin above a level of a few parts per billion in the Martian surface soil. Although the Viking GC/MS instruments were not specifically designed to search for the presence of living cells on Mars, our experimental results indicate that at the part per billion level, the degradation products generated from several million bacterial cells per gram of Martian soil would not have been detected.

Glavin, Daniel↗
NASA NTRS2003

Mechanosensitive Ion Channels in Bacteria: Functional Domains and Mechanisms of Gating

The past funding period was productive for the group. The progress in the mechanosensitive channel field was critically affected in the end of 1998 by the solution of the crystal structure of the mycobacterial homolog of MscL by our colleagues from Caltech. Having the structure of TbMscL in the closed state, we developed a detailed homology model of EcoMscL, and related the structural model with the wealth of functional phenomenology available for the E. coli version of the channel (EcoMscL). The biophysical properties of the open MscL helped to model the open conformation and infer the pathway for the entire gating transition. The following experiments provided strong support to the atomic model of the gating process, and allowed to make further predictions. The work has advanced our understanding of tension-driven conformational transitions in membrane-embedded mechanosensory proteins, determine major energetic contributions and set the stage for further exploration of the whole family of mechanosensitive channels. The results have been published in seven experimental and theoretical papers, with three other papers currently in press or in preparation.

Sukharev, Sergei↗
NASA NTRS2004

Hydrophobic Surfaces of Spacecraft Components Enhance the Aggregation of Microorganisms and May Lead to Higher Survival Rates of Bacteria on Mars Landers

In order to minimize the forward contamination of Mars, spacecraft are assembled under cleanroom conditions that require several procedures to clean and sterilize components. Surface characteristics of spacecraft materials may contribute to microbial survival on the surface of Mars by protecting spores from sterilizing agents, including UV irradiation. The primary objective of this study was to evaluate the effects of surface characteristics of several spacecraft materials on the survival of Bacillus subtilis spores under simulated Martian conditions.

Schuerger, Andrew C.↗
NASA NTRS2004

Detecting Pyrolysis Products from Bacteria in a Mars Soil Analogue

One of the primary objectives of the 1976 Viking missions was to determine whether organic compounds, possibly of biological origin, were present in the Martian surface soils. The Viking gas chromatography mass spectrometry (GCMS) instruments found no evidence for any organic compounds of Martian origin above a few parts per billion in the upper 10 cm of surface soil, suggesting the absence of a widely distributed Martian biota. However, it is now known that key organic compounds important to biology, such as amino acids, carboxylic acids and nucleobases, would likely have been missed by the Viking GCMS instruments. In this study, a Mars soil analogue that was inoculated with approx. 10 billion Escherichia coli cells was heated at 500 C under Martian ambient pressure to release volatile organic compounds from the sample. The pyrolysis products were then analyzed for amino acids and nucleobases using high performance liquid chromatography (HPLC) and GCMS. Our experimental results indicate that at the part per billion level, the degradation products generated from several million bacterial cells per gram of Martian soil would not have been detected by the Viking GCMS instruments. Upcoming strategies for Mars exploration will require in-situ analyses by instruments that can assess whether any organic compounds, especially those that might be associated with life, are present in Martian surface samples.

Glavin, D. P.↗