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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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25 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Kinetic studies on the control of the bean rust fungus (Uromyces phaseoli L.) by an inhibitor of polyamine biosynthesis

alpha-Difluoromethylornithine (DFMO), a specific and irreversible inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase, effectively inhibits mycelial growth of several phytopathogenic fungi on defined media in vitro and provides systemic protection of bean plants against infection by Uromyces phaseoli L. race 0 (MV Rajam, AW Galston 1985 Plant Cell Physiol 26: 683-692; MV Rajam et al. 1985 Proc Natl Acad Sci USA 82: 6874-6878). We now find that application of 0.5 millimolar DFMO to unifoliolate leaves of Pinto beans up to 3 days after inoculation with uredospores of U. phaseoli completely inhibits the growth of the pathogen, while application 4 or 5 days after inoculation results in partial protection against the pathogen. Spores do not germinate on the surface of unifoliolate leaves treated with DFMO 1 day before infection, but addition of spermidine to the DFMO treatments partially reverses the inhibitory effect. The titer of polyamines in bean plants did not decline after DFMO treatment; rather, putrescine and spermidine contents actually rose, probably due to the known but paradoxical stimulation of arginine decarboxylase activity by DFMO.

Non-NASA Center↗
NASA NTRS2013

Microbial Monitoring of the International Space Station

Humans living and working in the harsh environment of space present many challenges for habitability engineers and microbiologists. Spacecraft must provide an internal environment in which physical (gas composition, pressure, temperature, and humidity), chemical, and biological environmental parameters are maintained at safe levels. Microorganisms are ubiquitous and will accompany all human-occupied spacecraft, but if biological contamination were to reach unacceptable levels, long-term human space flight would be impossible. Prevention of microbiological problems, therefore, must have a high priority. Historically, prevention of infectious disease in the crew has been the highest priority, but experience gained from the NASA-Mir program showed that microbial contamination of vehicle and life-support systems, such as biofouling of water and food, are of equal importance. The major sources of microbiological risk factors for astronauts include food, drinking water, air, surfaces, payloads, research animals, crew members, and personnel in close contact with the astronauts. In our efforts to eliminate or mitigate the negative effects of microorganisms in spacecraft, the National Aeronautics and Space Administration (NASA) implemented comprehensive microbial analyses of the major risk factors. This included the establishment of acceptability requirements for food, water, air, surfaces, and crew members. A robust monitoring program was then implemented to verify that the risks were within acceptable limits. Prevention of microbiological problems is preferred over mitigation of problems during flight, and preventive steps must begin very early in the design phase. Spacecraft development must include requirements to control free water from humidity, condensate, hygiene activities, and other releases. If water is available, microbes are likely to grow because sufficient nutrients are potentially available. Materials selected for the spacecraft must not promote or support microbial growth. Air filtration can dramatically reduce the number of airborne bacteria, fungi, and particulates in spacecraft breathing air. Waterborne bacteria can be reduced to acceptable levels by thermal inactivation of bacteria during water processing, along with a residual biocide, and filtration at the point of use can ensure safety. System design must include onboard capability to achieve recovery of the system from contamination. Robust housekeeping procedures that include periodic cleaning and disinfection will prevent high levels of microbial growth on surfaces. Food for consumption in space must be thoroughly tested for excessive microbial content and pathogens before launch. Thorough preflight examination of flight crews, consumables, payloads, and the environment can greatly reduce pathogens in spacecraft. Many of the lessons learned from the Space Shuttle and previous programs were applied in the early design phase of the International Space Station, resulting in the safest space habitat to date. This presentation describes the monitoring program for the International Space Station and will summarize results from preflight and on-orbit monitoring.

Pierson, Duane L.↗
NASA NTRS2015

Veggie ISS Validation Test Results and Produce Consumption

The Veggie vegetable production system flew to the International Space Station (ISS) in the spring of 2014. The first set of plants, Outredgeous red romaine lettuce, was grown, harvested, frozen, and returned to Earth in October. Ground control and flight plant tissue was sub-sectioned for microbial analysis, anthocyanin antioxidant phenolic analysis, and elemental analysis. Microbial analysis was also performed on samples swabbed on orbit from plants, Veggie bellows, and plant pillow surfaces, on water samples, and on samples of roots, media, and wick material from two returned plant pillows. Microbial levels of plants were comparable to ground controls, with some differences in community composition. The range in aerobic bacterial plate counts between individual plants was much greater in the ground controls than in flight plants. No pathogens were found. Anthocyanin concentrations were the same between ground and flight plants, while antioxidant and phenolic levels were slightly higher in flight plants. Elements varied, but key target elements for astronaut nutrition were similar between ground and flight plants. Aerobic plate counts of the flight plant pillow components were significantly higher than ground controls. Surface swab samples showed low microbial counts, with most below detection limits. Flight plant microbial levels were less than bacterial guidelines set for non-thermostabalized food and near or below those for fungi. These guidelines are not for fresh produce but are the closest approximate standards. Forward work includes the development of standards for space-grown produce. A produce consumption strategy for Veggie on ISS includes pre-flight assessments of all crops to down select candidates, wiping flight-grown plants with sanitizing food wipes, and regular Veggie hardware cleaning and microbial monitoring. Produce then could be consumed by astronauts, however some plant material would be reserved and returned for analysis. Implementation of this plan is a step toward developing pick-and-eat food production to supplement the packaged diet on ISS and for future exploration missions where plants could make up a larger portion of the diet. Supported by NASA Space Biology Program.

Food Safety↗
NASA NTRS2011

Characterization of Volume F Trash from the Three FY11 STS Missions: Trash Weights and Categorization and Microbial Characterization

The project reported here provides microbial characterization support to the Waste Management Systems (WMS) element of NASA's Life Support and Habitation Systems (LSHS) program. Conventional microbiological methods were used to detect and enumerate microorganisms in STS Volume F Compartment trash for three shuttle missions: STS 133, 134, and 135. This trash was usually made available within 2 days of landing at KSC. The Volume F bag was weighed, opened and the contents were cataloged and placed into categories: personal hygiene items - inclUding EVA maximum absorbent garments (MAGs) and Elbow packs (daily toilet wipes, etc), drink containers, food waste (and containers), office waste (paper), and packaging materials - plastic film and duct tape. The average wet trash generation rate for the three STS missions was 0.362 % 0.157 kgwet crew 1 d-1 . This was considerably lower and more variable than the average rate for 4 STS missions reported for FY10. Trash subtotals by category: personal hygiene wastes, 56%; drink items, 11 %; food wastes, 18%; office waste, 3%; and plastic film, 12%. These wastes have an abundance of easily biodegraded compounds that can support the growth of microorganisms. Microbial characterization of trash showed that large numbers of bacteria and fungi have taken advantage of this readily available nutrient source to proliferate. Exterior and interior surfaces of plastic film bags containing trash were sampled and counts of cultivatable microbes were generally low and mostly occurred on trash bundles within the exterior trash bags. Personal hygiene wastes, drink containers, and food wastes and packaging all contained high levels of, mostly, aerobic heterotrophic bacteria and lower levels of yeasts and molds. Isolates from plate count media were obtained and identified .and were mostly aerobic heterotrophs with some facultative anaerobes. These are usually considered common environmental isolates on Earth. However, several pathogens were also isolated: Staphylococcus aureus and Escherichia coli.

Strayer, Richard F.↗
NASA NTRS2011

Methods of Antimicrobial Coating of Diverse Materials

Methods of coating diverse substrate materials with antimicrobial agents have been developed. Originally intended to reduce health risks to astronauts posed by pathogenic microorganisms that can grow on surfaces in spacecraft, these methods could also be used on Earth for example, to ensure sterility of surgical inserts and other medical equipment. The methods involve, generally, chemical preparation of substrate surfaces to enable attachment of antimicrobial molecules to the substrate surfaces via covalent bonds. Substrate materials that have been treated successfully include aluminum, glass, a corrosion-resistant nickel alloy, stainless steel, titanium, and poly(tetrafluoroethylene). Antimicrobial agents that have been successfully immobilized include antibiotics, enzymes, bacteriocins, bactericides, and fungicides. A variety of linkage chem istries were employed. Activity of antimicrobial coatings against gram-positive bacteria, gram-negative bacteria, and fungi was demonstrated. Results of investigations indicate that the most suitable combination of antimicrobial agent, substrate, and coating method depends upon the intended application.

Akse, James R.↗
NASA NTRS2026

Does the International Space Station Leak DNA? Preliminary Results from the ISS External Microorganisms Payload

Existing crewed spacecraft like the ISS (International Space Station) leak by design. The ISS routinely releases gas to maintain life support systems and when astronauts exit the station to perform space walks. The chemical component of this leakage is well characterized, but the biological components are not. The ISS is not subject to planetary protection requirements, but planned missions to Mars will use similar systems and will be subject to planetary protection requirements. If detectable microorganisms are escaping through vents and or airlocks we may need to redesign our crewed habitats to minimize this type of contamination. To test the hypothesis that microorganisms from inside ISS are detectable on exterior surfaces an astronaut used the ISS External Microorganisms sampling kit (Rucker et al. 2018) to sample exterior surfaces of the ISS during an EVA (Extra Vehicular Activity) in January of 2025. These samples were returned to Earth for DNA extraction and sequencing. We successfully, extracted and sequenced bacterial, fungal and viral DNA from these samples that was not present in the negative controls. These results should help NASA refine the planetary protection requirements for crewed missions. Methods: The samples were collected using sterile, DNA free, buccal swabs (23 mm. diameter) housed in custom canisters. Each canister uses a 0.2 μm Teflon filter to maintain sterility as the caddy, holding 8 swabs moves in and out of vacuum. The astronaut sampled the: 1) airlock vestibule, 2) airlock thermal cover, 3) a gap in the micrometeorite shielding near the airlock, 4) a handrail near the airlock, 5) the Carbon Dioxide Removal Assembly vent, and 6) the Vacuum Exhaust System vent. The seventh swab was exposed to vacuum during the EVA without touching it to a surface. The eighth swab, a negative control, was not opened until the caddy returned to Earth. DNA was extracted from the swabs using a QIamp UCP Pathogen kit and prepared for sequencing on an Aviti (Element Biosciences) sequencer (Arslan et al. 2024). The resulting sequences were analyzed using the EDGE Bioinformatics platform (Li et al. 2017). The sequences were analyzed individually using tools like BLAST, GOTTCHA2, Kraken2, and PanGIA. The data were also assembled into metagenome assembled genomes) using tools like CONCOCT, MaxBin2 and MetaBAT2. Results: We successfully extracted and sequenced bacterial, archaeal, fungal and viral DNA from all seven samples. The handrail swab had the lowest number of reads (768,651) and the airlock thermal cover had the highest number of reads (8,819,230). These samples contain DNA from human associated bacteria (e.g. Crynebacterium riegelii ), fungi (.e.g. Penicillium rubens ), and viruses (e.g Alphapapillomavirus ). Conclusion: Preliminary interpretation suggest that the airlock and the space suits themselves are the largest sources of contaminant DNA. Most if not all of the DNA is from organisms known to be present inside the ISS. Vents attached to life support systems may be a lesser source of biological contamination. Further analysis should help NASA address planetary protection knowledge gaps for crewed missions.

Aaron B Regberg↗
NASA NTRS2012

Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment

The determination of risk from infectious disease during spaceflight missions is composed of several factors including both the concentration and characteristics of the microorganisms to which the crew are exposed. Thus, having a good understanding of the microbial ecology aboard spacecraft provides the necessary information to mitigate health risks to the crew. While preventive measures are taken to minimize the presence of pathogens on spacecraft, medically significant organisms have been isolated from both the Mir and International Space Station (ISS). Historically, the method for isolation and identification of microorganisms from spacecraft environmental samples depended upon their growth on culture media. Unfortunately, only a fraction of the organisms may grow on a specific culture medium, potentially omitting those microorganisms whose nutritional and physical requirements for growth are not met. To address this bias in our understanding of the ISS environment, the Surface, Water, and Air Biocharacterization (SWAB) Flight Experiment was designed to investigate and develop monitoring technology to provide better microbial characterization. For the SWAB flight experiment, we hypothesized that environmental analysis using non-culture-based technologies would reveal microorganisms, allergens, and microbial toxins not previously reported in spacecraft, allowing for a more complete health assessment. Key findings during this experiment included: a) Generally, advanced molecular techniques were able to reveal a few organisms not recovered using culture-based methods; however, there is no indication that current monitoring is "missing" any medically significant bacteria or fungi. b) Molecular techniques have tremendous potential for microbial monitoring, however, sample preparation and data analysis present challenges for spaceflight hardware. c) Analytical results indicate that some molecular techniques, such as denaturing gradient gel electrophoresis (DGGE), can be much less sensitive than culture-based methods. d) More sensitive molecular techniques, such as quantitative polymerase chain reaction (QPCR), were able to identify viral DNA from ISS environments, suggesting potential transfer of the organism between crewmembers. In addition, the hardware selected for this experiment represented advances for next-generation sample collection. The advanced nature of this collection hardware was noted, when the Sartorius MD8 Air Port air sampler from the SWAB experiment remained on board ISS at the request of JAXA investigators, who intend to use it in completion of their microbial ecology experiment.

Castro, V. A.↗