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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS2001

Abiotic Versus Biotic Weathering Of Olivine As Possible Biosignatures

We are investigating the weathering of silicate minerals by both purely inorganic, and biologically mediated processes using field-emission scanning electron microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDS). By resolving surface textures and chemical compositions of weathered surfaces at the sub-micron scale we hope to be able to distinguish abiotic from biotic weathering processes and so establish a new biosignature applicable to the study of astromaterials including but not limited to the Martian meteorites. Sterilized olivine grains (San Carlos, Arizona) no more than 1-2 mm in their longest dimension were optically assayed to be uniform in color and free of inclusions were selected as weathering subjects. Prior to all experiments surface morphologies and Fe/Mg ratios were determined for each grain using FE-SEM and EDS. Experiments were divided into two categories abiotic and biotic and were compared with "naturally" weathered samples. For the preliminary experiments, two trials (open and closed to the ambient laboratory environment) were performed under abiotic conditions, and three trials under biotic conditions (control, day 1 and day 2). The open system abiotic trials used sterile grains heated at 98 C and 200 C for both 24 and 48 hours in 1L double distilled de-ionized water. The closed system abiotic trials were conducted under the same conditions but in a sealed two layer steel/Teflon "bomb" apparatus. The biotic trials used sterile grains mounted in a flow-through device attached to a wellhead on the Columbia River aquifer. Several discolored, altered, grains were selected to document "natural" weathering surface textures for comparison with the experimental samples. Preliminary results indicate there are qualitative differences in weathered surface textures among all the designed experiments. The olivine grains in abiotic trials displayed etching, pitting, denticulate margins, dissolution and clay formation. The scale of the features ranged from tens to a few microns with textures that remained relatively sharp and were crystallographically controlled. These results were comparable to that observed in the "naturally" weathered comparison/reference grains. Chemical analysis by EDS indicates these textures correlated with the relative loss of Mg and Fe cations by diffusional processes. In contrast the biotic results indicated changes in the etching patterns on the scale of hundreds of nm, which are neither sharp nor crystallographically controlled (nanoetching). Organisms, organic debris and/or extracellular polymeric substances (biofilm) were often in close proximity or direct contact with the nanoetching. While there are many poorly constrained variables in natural weathering experiments to contend with, such as the time scale, the chemistry of the fluids and degree of biologic participation, some preliminary observations can be made: (1) certain distinct surface textures appear correlated with the specific processes giving rise to these textures; (2) the process of diffusing cations can produce many similar styles of surface textural changes; and (3) the main difference between abiotic and biotically produced weathering is the scale (microns versus nanometers) and the style (crystallographically versus noncrystallographically controlled) of the textural features. Further investigation into nanosize scale surface textures should attempt to quantify both textures and chemical changes of the role of microorganisms in the weathering of silicates. Additional experiments addressing nanoscale textures of shock features for comparison with the current data set.

Longazo, Teresa G.↗
NASA NTRS1995

Fossilization Processes in Thermal Springs

To create a comparative framework for the study of ancient examples, we have been carrying out parallel studies of the microbial biosedimentology, taphonomy and geochemistry of modem and sub-Recent thermal spring deposits. One goal of the research is the development of integrated litho- and taphofacies models for siliceous and travertline sinters. Thermal springs are regarded as important environments for the origin and early evolution of life on Earth, and we seek to utilize information from the fossil record to reconstruct the evolution of high temperature ecosystems. Microbial contributions to the fabric of thermal spring sinters occur when population growth rates keep pace with, or exceed rates of inorganic precipitation, allowing for the development of continuous biofilms or mats. In siliceous thermal springs, microorganisms are typically entombed while viable. Modes of preservation reflect the balance between rates of organic matter degradation, silica precipitation and secondary infilling. Subaerial sinters are initially quite porous and permeable and at temperatures higher than about 20 C, organic materials are usually degraded prior to secondary infilling of sinter frameworks. Thus, organically-preserved microfossils are rare and fossil information consists of characteristic biofabrics formed by the encrustation and underplating of microbial mat surfaces. This probably accounts for the typically low total organic carbon values observed in thermal spring deposits. In mid-temperature, (approx. 35 - 59 C) ponds and outflows, the surface morphology of tufted Phormidium mats is preserved through mat underplating by thin siliceous: crusts. Microbial taxes lead to clumping of ceils and/or preferred filament orientations that together define higher order composite fabrics in thermal spring stromatolites (e.g. network, coniform, and palisade). At lower temperatures (less than 35 C), Calothrix mats cover shallow terracette pools forming flat carpets or pustular surfaces that produce palisade and "shrub" fabrics, respectively. At finer scales, composite fabrics are seen to consist distinctive associations of microstructures formed by the encrustation of individual cells and filaments. Composite fabrics survive the diagenetic transitions from primary opaline silica to quartz and are known from subaerial thermal spring deposits as old as Lower Carboniferous. However, fossil microorganisms tend to be rare in older deposits, and are usually preserved only where cells or sheaths have been stained by iron oxides. In subaqueous mineralizing springs at lower temperatures, early infilling leads to a more rapid and complete reduction in porosity and permeability. This process, along with the slower rates of microbial degradation at lower temperatures, creates a more favorable situation for organic matter preservation. Application of this taphonomic model to the Rhynie Chert, previously interpreted as subaerial, suggest it was probably deposited in a subaqueous spring setting at lower temperatures.

Farmer, Jack D.↗
NASA NTRS2002

Microbial Weathering of Olivine

Controlled microbial weathering of olivine experiments displays a unique style of nanoetching caused by biofilm attachment to mineral surfaces. We are investigating whether the morphology of biotic nanoetching can be used as a biosignature. Additional information is contained in the original extended abstract.

McKay, D. S.↗
NASA NTRS2002

Second International Conference on Near-Field Optical Analysis: Photodynamic Therapy and Photobiology Effects

The International NASA/DARPA Photobiology Conference held at the Johnson Space Center in Houston/TX demonstrated where low level laser therapy (LLLT), respectively low intensity light activated biostimulation (LILAB) and nanotechnological applications employing photobiomodulation techniques will presumably go in the next ten years. The conference was a continuation of the 1st International Conference on Nearfield Optical Analysis organized by Andrei Sommer (ENSOMA Lab, University of Ulm, Germany) in November 2000 at Castle Reisenburg, Germany, which started with a group of ten scientists from eight different countries. The 1st conference was co-sponsored by the American Chemical Society to evaluate the molecular mechanism of accelerated and normal wound healing processes. The 2nd conference was co-sponsored by DARPA, NASA-JSC and the Medical College of Wisconsin. Despite the short time between events, the 2nd conference hosted 40 international experts form universities, research institutes, agencies and the industry. The materials published here are expected to become milestones forming a novel platform in biomedical photobiology. The multidisciplinary group of researchers focused on LLLT/LILAB-applications under extreme conditions expected to have beneficial effects particularly in space, on submarines, and under severe battlefield conditions. The group also focused on novel technologies with possibilities allowing investigating the interaction of light with biological systems, molecular mechanisms of wound healing, bone regeneration, nerve regeneration, pain modulation, as well as biomineralization and biofilm formulation processes induced by nanobacteria.

Bulgher, Debra L.↗
NASA NTRS2003

Records of our Early Biosphere Illuminate our Origins and Guide our Search for Life Beyond Earth

A scientific "mission of exploration to early Earth" will help us chart the distribution of life elsewhere. We must discriminate between attributes of biospheres that are universal versus those attributes that represent principally the outcomes of long-term survival specifically on Earth. In addition to the basic physics and chemistry of matter, the geologic evolution of rocky habitable planets and their climates might be similar elsewhere in the Universe. Certain key agents that drive long-term environmental change (e.g., stellar evolution, impacts, geothermal heat flow, tectonics, etc.) can help us to reconstruct ancient climates and to compare their evolution among populations of Earth- like planets. Early Earth was tectonically more active than today and therefore it exhaled reduced chemical species into the more oxidized surface environment at greater rates. This tectonic activity thus sustained oxidation-reduction reactions that provided the basis for the development of biochemical pathways that harvest chemical energy ("bioenergetics"). Most examples of bioenergetics today that extract energy by reacting oxidized and reduced chemicals in the environment were likely more pervasive among our microbial ancestors than are the presently known examples of photosynthesis. The geologic rock record indicates that, as early as 3.5 billion years ago (3.5 Ga), microbial biofilms were widespread within the coastal environments of small continents and tectonically unstable volcanic islands. Non oxygen-producing (non-oxygenic) photosynthesis preceded oxygenic photosynthesis, but all types of photosynthesis contributed substantially to the long-term increase in global primary biological productivity. Evidence of photosynthesis is tentative by 3.5 Ga and compelling by 2.7 Ga. Evidence of oxygenic photosynthesis is strong by 2.7 Ga and compelling by 2.3 Ga. These successive innovations transformed life from local communities that survived principally by catalyzing chemical equilibration to a globally dominant agent that created and sustained widespread chemical disequilibria in the environment and shallow crust. Major biogeochemical perturbations ca. 2.3 to 2.0 Ga, 1.3 Ga, and also 0.8 to 0.6 Ga, contributed to the irreversible oxidation of the global environment and perhaps also triggered evolutionary innovations (e.g., the development of multi-cellular biota) that became the foundations of our modern biosphere. Understanding the nature and timing of this ascent of life is crucial for discerning our o m beginnings. This understanding also empowers OUT search for the origins, evolution and distribution of life elsewhere in our solar system and beyond.

DesMarais, David J.↗
NASA NTRS1985

Precision and sensitivity of the measurement of 15N enrichment in D-alanine from bacterial cell walls using positive/negative ion mass spectrometry

Sensitive detection of cellular components from specific groups of microbes can be utilized as 'signatures' in the examination of microbial consortia from soils, sediments or biofilms. Utilizing capillary gas chromatography/mass spectrometry and stereospecific derivatizing agents, D-alanine, a component localized in the prokaryotic (bacterial) cell wall, can be detected reproducibly. Enrichments of D-[15N]alanine determined in E. coli grown with [15N]ammonia can be determined with precision at 1.0 atom%. Chemical ionization with methane gas and the detection of negative ions (M - HF)- and (M - F or M + H - HF)- formed from the heptafluorobutyryl D-2 butanol ester of D-alanine allowed as little as 8 pg (90 fmol) to be detected reproducibly. This method can be utilized to define the metabolic activity in terms of 15N incorporation at the level of 10(3)-10(4) cells, as a function of the 15N-14N ratio.

Non-NASA Center↗
NASA NTRS1996

Engineering strategies for the design of plant nutrient delivery systems for use in space: approaches to countering microbiological contamination

Microbiological contamination of crops within space-based plant growth research chambers has been postulated as a potentially significant problem. Microbial infestations; fouling of Nutrient Delivery System (NDS) fluid loops; and the formation of biofilms have been suggested as the most obvious and important manifestations of the problem. Strict sanitation and quarantine procedures will reduce, but not eliminate, microbial species introduced into plant growth systems in space habitats. Microorganisms transported into space most likely will occur as surface contaminants on spacecraft components, equipment, the crew, and plant-propagative materials. Illustrations of the potential magnitude of the microbiological contamination issue will be drawn from the literature and from documentation of laboratory and commercial field experience. Engineering strategies for limiting contamination and for the development of countermeasures will be described. Microbiological control technologies and NDS hardware will be discussed. Configurations appropriate for microgravity research facilities, as well as anticipated bio-regenerative life support system implementations, will be explored. An efficiently designed NDS, capable of adequately meeting the environmental needs of crop plants in space, is considered to be critical in both the research and operational domains. Recommended experiments, tests, and technology developments, structured to allow the development of prudent engineering solutions also will be presented.

NASA Discipline Number 61-10↗
NASA NTRS2004

New Evidence for the Presence of Indigenous Microfossils in Carbonaceous Chondrites

We present additional evidence for the presence of indigenous microfossils in carbonaceous meteorites scanning electron micrograph studies of freshly fractured interior surfaces of pristine samples of the Murchison CM2 carbonaceous meteorite have revealed forms in-situ that are recognizable as biofilms as well as complex and highly structured forms similar to calcareous and siliceous microfossils. Some of the forms encountered are very well-preserved and exhibit complex associated microstructures similar to bacterial flagella. New images will be presented of forms recently encountered in carbonaceous meteorites and they will be compared with those of known microbial extremophiles. KEYWORDS: carbonaceous chondrites, Murchison, microfossils, extremophiles

Hoover, Richard B.↗
NASA NTRS2001

The release of alginate lyase from growing Pseudomonas syringae pathovar phaseolicola

Pseudomonas syringae pathovar phaseolicola, which produces alginate during stationary growth phase, displayed elevated extracellular alginate lyase activity during both mid-exponential and late-stationary growth phases of batch growth. Intracellular activity remained below 22% of the total activity during exponential growth, suggesting that alginate lyase has an extracellular function for this organism. Extracellular enzyme activity in continuous cultures, grown in either nutrient broth or glucose-simple salts medium, peaked at 60% of the washout rate, although nutrient broth-grown cultures displayed more than twice the activity per gram of cell mass. These results imply that growth rate, nutritional composition, or both initiate a release of alginate lyase from viable P. syringae pv. phaseolicola, which could modify its entrapping biofilm.

Polysaccharide-Lyases/secretion↗
NASA NTRS1997

Fungal degradation of fiber-reinforced composite materials

As described in a previous report, a fungal consortium isolated from degraded polymeric materials was capable of growth on presterilized coupons of five composites, resulting in deep penetration into the interior of all materials within five weeks. Data describing the utilization of composite constituents as nutrients for the microflora are described in this article. Increased microbial growth was observed when composite extract was incubated with the fungal inoculum at ambient temperatures. Scanning electron microscopic observation of carbon fibers incubated with a naturally developed population of microorganisms showed the formation of bacterial biofilms on the fiber surfaces, suggesting possible utilization of the fiber chemical sizing as carbon and energy sources. Electrochemical impedance spectroscopy was used to monitor the phenomena occurring at the fiber-matrix interfaces. Significant differences were observed between inoculated and sterile panels of the composite materials. A progressive decline in impedance was detected in the inoculated panels. Several reaction steps may be involved in the degradation process. Initial ingress of water into the resin matrix appeared to be followed by degradation of fiber surfaces, and separation of fibers from the resin matrix. This investigation suggested that composite materials are susceptible to microbial attack by providing nutrients for growth.

Environmental Microbiology↗
NASA NTRS2004

Response of graywater recycling systems based on hydroponic plant growth to three classes of surfactants

Anionic (sodium laureth sulfate, SLES), amphoteric (cocamidopropyl betaine, CAPB) and nonionic (alcohol polyethoxylate, AE) surfactants were added to separate nutrient film technique (NFT) hydroponic systems containing dwarf wheat (Triticum aestivum cv. USU Apogee) in a series of 21 day trials. Surfactant was added either in a (1). temporally dynamic mode (1-3 g surfactant m(-2) growing area d(-1)) as effected by automatic addition of a 300 ppm surfactant solution to meet plant water demand, or (2). continuous mode (2 g surfactant m(-2) growing area d(-1)) as effected by slow addition (10 mLh(-1)) of a 2000 ppm surfactant solution beginning at 4d after planting. SLES showed rapid primary degradation in both experiments, with no accumulation 24 h after initial addition. CAPB and AE were degraded less rapidly, with 30-50% remaining 24 h after initial addition, but CAPB and AE levels were below detection limit for the remainder of the study. No reductions in vegetative growth of wheat were observed in response to SLES, but biomass was reduced 20-25% with CAPB and AE. Microbial communities associated with both the plant roots and wetted hardware surfaces actively degraded the surfactants, as determined by monitoring surfactant levels following pulse additions at day 20 (with plants) and day 21 (after plant removal). In order to test whether the biofilm communities could ameliorate phytotoxicity by providing a microbial community acclimated for CAPB and AE decay, the continuous exposure systems were planted with wheat seeds after crop removal at day 21. Acclimation resulted in faster primary degradation (>90% within 24h) and reduced phytotoxicity. Overall, the studies indicate that relatively small areas (3-5m(2)) of hydroponic plant systems can process per capita production of mixed surfactants (5-10 g x person(-1)d(-1)) with minimal effects on plant growth.

Hydroponics↗
NASA NTRS2005

Use of a Novel Rover-mounted Fluorescence Imager and Fluorescent Probes to Detect Biological Material in the Atacama Desert in Daylight

We have developed an imaging system, the Fluorescence Imager (FI), for detecting fluorescence signals from sparse microorganisms and biofilms during autonomous rover exploration. The fluorescence signals arise both from naturally occurring chromophores, such as chlorophyll of cyanobacteria and lichens, and from fluorescent probes applied to soil and rocks. Daylight imaging has been accomplished by a novel use of a high-powered flashlamp synchronized to a CCD camera. The fluorescent probes are cell permanent stains that have extremely low intrinsic fluorescence (quantum yields less than 0.01) and a large fluorescence enhancement (quantum yields greater than 0.4) when bound to the target. Each probe specifically targets either carbohydrates, proteins, nucleic acids or membrane lipids, the four classes of macromolecules found in terrestrial life. The intent of the probes is to interrogate the environment for surface and endolithic life forms.

Weinstein, S.↗
NASA NTRS2005

Microbiological Characterization and Concerns of the International Space Station Internal Active Thermal Control System

Since January 1999, the chemical the International Space Station Thermal Control System (IATCS) and microbial state of (ISS) Internal Active fluid has been monitored by analysis of samples returned to Earth. Key chemical parameters have changed over time, including a drop in pH from the specified 9.5 +/- 0.5 ta = 58.4, an increase in the level of total inorganic carbon (TIC), total organic carbon (TOC) and dissolved nickel (Ni) in the fluid, and a decrease in the phosphate (PO,) level. In addition, silver (AS) ion levels in the fluid decreased rapidly as Ag deposited on internal metallic surfaces of the system. The lack of available Ag ions coupled with changes in the fluid chemistry has resulted in a favorable environment for microbial growth. Counts of heterotrophic bacteria have increased from less than 10 colony-forming units (CFUs)/l00 mL to l0(exp 6) to l0(exp 7) CFUs/100 mL. The increase of the microbial population is of concern because uncontrolled microbiological growth in the IATCS can contribute to deterioration in the performance of critical components within the system and potentially impact human health if opportunistic pathogens become established and escape into the cabin atmosphere. Micro-organisms can potentially degrade the coolant chemistry; attach to surfaces and form biofilms; lead to biofouling of filters, tubing, and pumps; decrease flow rates; reduce heat transfer; initiate and accelerate corrosion; and enhance mineral scale formation. The micro- biological data from the ISS IATCS fluid, and approaches to addressing the concerns, are summarized in this paper.

Roman, Monsi C.↗
NASA NTRS2005

Assessment of Microbiologically Influenced Corrosion Potential in the International Space Station Internal Active Thermal Control System Heat Exchanger Materials: A 6-Momths Study

The fluid in the Internal Active Thermal Control System (IATCS) of the International Space Station (ISS) is water based. The fluid in the ISS Laboratory Module and Node 1 initially contained a mix of water, phosphate (corrosion control), borate (pH buffer), and silver sulfate (Ag2SO4) (microbial control) at a pH of 9.5+/-0.5. Over time, the chemistry of the fluid changed. Fluid changes included a pH drop from 9.5 to 8.3 due to diffusion of carbon dioxide (CO2) through Teflon(reistered Trademark) (DuPont) hoses, increases in dissolved nickel (Ni) levels, deposition of silver (Ag) to metal surfaces, and precipitation of the phosphate (PO4) as nickel phosphate (NiPO4). The drop in pH and unavailability of a antimicrobial has provided an environment conducive to microbial growth. Microbial levels in the fluid have increased from >10 colony-forming units (CFUs)/100 ml to 10(exp 6) CFUs/100 ml. The heat exchangers in the IATCS loops are considered the weakest point in the loop because of the material thickness (=7 mil). It is made of a Ni-based braze filler/CRES 347. Results of a preliminary test performed at Hamilton Sundstrand indicated the possibility of pitting on this material at locations where Ag deposits were found. Later, tests have confirmed that chemical corrosion of the materials is a concern for this system. Accumulation of micro-organisms on surfaces (biofilm) can also result in material degradation and can amplify the damage caused by the chemical corrosion, known as microbiologically influenced corrosion (MIC). This paper will discuss the results of a 6-mo test performed to characterize and quantify the damage from microbial accumulation on the surface of the ISS/ATCS heat exchanger materials. The test was designed to quantify the damage to the materials under worst-case conditions with and without micro-organisms present at pH 8.3 and 9.5.

Roman, Monsi C.↗
NASA NTRS2004

Microbial Paleontology, Mineralogy and Geochemistry of Modern and Ancient Thermal Spring Deposits and Their Recognition on the Early Earth and Mars"

The vision of this project was to improve our understanding of the processes by which microbiological information is captured and preserved in rapidly mineralizing sedimentary environments. Specifically, the research focused on the ways in which microbial mats and biofilms influence the sedimentology, geochemistry and paleontology of modem hydrothermal spring deposits in Yellowstone national Park and their ancient analogs. Toward that goal, we sought to understand how the preservation of fossil biosignatures is affected by 1) taphonomy- the natural degradation processes that affect an organism from the time of its death, until its discovery as a fossil and 2) diagenesis- longer-term, post-depositional processes, including cementation and matrix recrystallization, which collectively affect the mineral matrix that contains fossil biosignature information. Early objectives of this project included the development of observational frameworks (facies models) and methods (highly-integrated, interdisciplinary approaches) that could be used to explore for hydrothermal deposits in ancient terranes on Earth, and eventually on Mars.

Farmer, Jack D.↗
NASA NTRS2004

Selection of an Alternate Biocide for the ISS Internal Thermal Control System Coolant, Phase 2

The ISS (International Space Station) ITCS (Internal Thermal Control System) includes two internal coolant loops that utilize an aqueous based coolant for heat transfer. A silver salt biocide had previously been utilized as an additive in the coolant formulation to control the growth and proliferation of microorganisms within the coolant loops. Ground-based and in-flight testing demonstrated that the silver salt was rapidly depleted, and did not act as an effective long-term biocide. Efforts to select an optimal alternate biocide for the ITCS coolant application have been underway and are now in the final stages. An extensive evaluation of biocides was conducted to down-select to several candidates for test trials and was reported on previously. Criteria for that down-select included: the need for safe, non-intrusive implementation and operation in a functioning system; the ability to control existing planktonic and biofilm residing microorganisms; a negligible impact on system-wetted materials of construction; and a negligible reactivity with existing coolant additives. Candidate testing to provide data for the selection of an optimal alternate biocide is now in the final stages. That testing has included rapid biocide effectiveness screening using Biolog MT2 plates to determine minimum inhibitory concentration (amount that will inhibit visible growth of microorganisms), time kill studies to determine the exposure time required to completely eliminate organism growth, materials compatibility exposure evaluations, coolant compatibility studies, and bench-top simulated coolant testing. This paper reports the current status of the effort to select an alternate biocide for the ISS ITCS coolant. The results of various test results to select the optimal candidate are presented.

Wilson, Mark E.↗
NASA NTRS2006

Design and Certification of the Extravehicular Activity Mobility Unit (EMU) Water Processing Jumper

The Extravehicular Mobility Units (EMUs) onboard the International Space Station (ISS) experienced a failure due to cooling water contamination from biomass and corrosion byproducts forming solids around the EMU pump rotor. The coolant had no biocide and a low pH which induced biofilm growth and corrosion precipitates, respectively. NASA JSC was tasked with building hardware to clean the ionic, organic, and particulate load from the EMU coolant loop before and after Extravehicular Activity (EVAs). Based on a return sample of the EMU coolant loop, the chemical load was well understood, but there was not sufficient volume of the returned sample to analyze particulates. Through work with EMU specialists, chemists, (EVA) Mission Operations Directorate (MOD) representation, safety and mission assurance, astronaut crew, and team engineers, requirements were developed for the EMU Water Processing hardware (sometimes referred to as the Airlock Coolant Loop Recovery [A/L CLR] system). Those requirements ranged from the operable level of ionic, organic, and particulate load, interfaces to the EMU, maximum cycle time, operating pressure drop, flow rate, and temperature, leakage rates, and biocide levels for storage. Design work began in February 2005 and certification was completed in April 2005 to support a return to flight launch date of May 12, 2005. This paper will discuss the details of the design and certification of the EMU Water Processing hardware and its components

Peterson, Laurie J.↗