Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “bacterial”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS2005

Surface characteristics of spacecraft components affect the aggregation of microorganisms and may lead to different survival rates of bacteria on Mars landers

Layers of dormant endospores of Bacillus subtilis HA101 were applied to eight different spacecraft materials and exposed to martian conditions of low pressure (8.5 mbar), low temperature (-10 degrees C), and high CO(2) gas composition and irradiated with a Mars-normal ultraviolet (UV-visible- near-infrared spectrum. Bacterial layers were exposed to either 1 min or 1 h of Mars-normal UV irradiation, which simulated clear-sky conditions on equatorial Mars (0.1 tau). When exposed to 1 min of Mars UV irradiation, the numbers of viable endospores of B. subtilis were reduced three to four orders of magnitude for two brands of aluminum (Al), stainless steel, chemfilm-treated Al, clear-anodized Al, and black-anodized Al coupons. In contrast, bacterial survival was reduced only one to two orders of magnitude for endospores on the non-metal materials astroquartz and graphite composite when bacterial endospores were exposed to 1 min of Mars UV irradiation. When bacterial monolayers were exposed to 1 h of Mars UV irradiation, no viable bacteria were recovered from the six metal coupons listed above. In contrast, bacterial survival was reduced only two to three orders of magnitude for spore layers on astroquartz and graphite composite exposed to 1 h of Mars UV irradiation. Scanning electron microscopy images of the bacterial monolayers on all eight spacecraft materials revealed that endospores of B. subtilis formed large aggregates of multilayered spores on astroquartz and graphite composite, but not on the other six spacecraft materials. It is likely that the formation of multilayered aggregates of endospores on astroquartz and graphite composite is responsible for the enhanced survival of bacterial cells on these materials.

Mars↗
NASA NTRS2000

A Robust Biomarker

Polymers of bacterial origin, either through cell secretion or the degraded product of cell lysis, form isolated mucoidal strands as well as well-developed biofilms on interfaces. Biofilms are structurally and compositionally complex and are readily distinguishable from abiogenic films. These structures range in size from micrometers to decimeters, the latter occurring as the well-known, mineralised biofilms called stromatolites. Compositionally bacterial polymers are greater than 90 % water, with while the majority of the macromolecules forming the framework of the polymers consisting of polysaccharides (with and some nucteic acids and proteins). These macromolecules contain a vaste amount of functional groups, such as carboxyls, hydroxyls, and phosphoryls which are implicated in cation-binding. It is the elevated metal- binding capacity which provides the bacterial polymer with structural support and also helps to preserves it for up to 3.5 b.y. in the terrestrial rock record. The macromolecules, thus, can become rapidly mineralised and trapped in a mineral matrix. Through early and late diagenesis (bacterial degradation, burial, heat, pressure and time) they break down, losing the functional groups and, gradually, their hydrogen atoms. The degraded product is known as "kerogen". With further diagenesis and metamorphism, all the hydrogen atoms are lost and the carbonaceous matter becomes graphite. until the remnant carbonaceous material become graphitised. This last sentence reads a bit as if ALL these macromolecules break down and end up as graphite., but since we find 441 this is not true for all of the macromolecules. We have traced fossilised polymer and biofilms in rocks from throughout Earth's history, to rocks as old as the oldest being 3.5 b.y.-old. Furthermore, Time of Flight Secondary Ion Mass Spectrometry has been able to identify individual macromolecules of bacterial origin, the identities of which are still being investigated, in all the samples containing fossil biofilm, including the 3.5 b.y..-old carbonaceous cherts from South Africa and Australia. As a result of the unique compositional, structural and "mineralisable" properties of bacterial polymer and biofilms, we conclude that bacterial polymers and biofilms constitute a robust and reliable biomarker for life on Earth and could be a potential biomarker for extraterrestrial life.

Westall, F.↗
NASA NTRS1985

Microbial biomass and productivity in seagrass beds

Different methods for measuring the rates of processes mediated by bacteria in sediments and the rates of bacterial cell production have been compared. In addition, net production of the seagrass Zostera capricorni and bacterial production have been compared and some interrelationships with the nitrogen cycle discussed. Seagrass productivity was estimated by measuring the plastochrone interval using a leaf stapling technique. The average productivity over four seasons was 1.28 +/- 0.28 g C m-2 day-1 (mean +/- standard deviation, n = 4). Bacterial productivity was measured five times throughout a year using the rate of tritiated thymidine incorporated into DNA. Average values were 33 +/- 12 mg C m-2 day-1 for sediment and 23 +/- 4 for water column (n = 5). Spatial variability between samples was greater than seasonal variation for both seagrass productivity and bacterial productivity. On one occasion, bacterial productivity was measured using the rate of 32P incorporated into phospholipid. The values were comparable to those obtained with tritiated thymidine. The rate of sulfate reduction was 10 mmol SO4(-2) m-2 day-1. The rate of methanogenesis was low, being 5.6 mg CH4 produced m-2 day-1. A comparison of C flux measured using rates of sulfate reduction and DNA synthesis indicated that anaerobic processes were predominant in these sediments. An analysis of microbial biomass and community structure, using techniques of phospholipid analysis, showed that bacteria were predominant members of the microbial biomass and that of these, strictly anaerobic bacteria were the main components. Ammonia concentration in interstitial water varied from 23 to 71 micromoles. Estimates of the amount of ammonia required by seagrass showed that the ammonia would turn over about once per day. Rapid recycling of nitrogen by bacteria and bacterial grazers is probably important.

NASA Program CELSS↗
NASA NTRS1978

Survival and reversion of a stable L form in soil

The stable L form of Agromyces ramosus reverted to a bacterial form when incubated in sterilized soil. The cellular and colonial morphology of this bacterial form resembled that of the original parent bacterial form. The two forms differed, however, in that the revertant maintained its bacterial form when transferred onto a low-salt (NaCl) medium but was virtually completely induced into the L-form state on a high-salt medium. The original parent bacterial form was not sensitive to salt. The possibility is discussed that an L-form - bacterial-form cycle for this bacterium might occur naturally in soil. This cycle would be mediated by fluctuations in local salt concentrations in the soil.

Horwitz, A. H.↗
NASA NTRS1973

Method of detecting and counting bacteria in body fluids

A novel method is reported for determining bacterial levels in urine samples, which method depends on the quantitative determination of bacterial adenosine triphosphate (ATP) in the presence of non-bacterial ATP. After the removal of non-bacterial ATP, the bacterial ATP is released by cell rupture and is measured by an enzymatic bioluminescent assay using an enzyme obtained from the firefly.

Chappelle, E. W.↗
NASA NTRS2003

Survival of endospores of Bacillus subtilis on spacecraft surfaces under simulated martian environments: implications for the forward contamination of Mars

Experiments were conducted in a Mars simulation chamber (MSC) to characterize the survival of endospores of Bacillus subtilis under high UV irradiation and simulated martian conditions. The MSC was used to create Mars surface environments in which pressure (8.5 mb), temperature (-80, -40, -10, or +23 degrees C), gas composition (Earth-normal N2/O2 mix, pure N2, pure CO2, or a Mars gas mix), and UV-VIS-NIR fluence rates (200-1200 nm) were maintained within tight limits. The Mars gas mix was composed of CO2 (95.3%), N2 (2.7%), Ar (1.7%), O2 (0.2%), and water vapor (0.03%). Experiments were conducted to measure the effects of pressure, gas composition, and temperature alone or in combination with Mars-normal UV-VIS-NIR light environments. Endospores of B. subtilis, were deposited on aluminum coupons as monolayers in which the average density applied to coupons was 2.47 x 10(6) bacteria per sample. Populations of B. subtilis placed on aluminum coupons and subjected to an Earth-normal temperature (23 degrees C), pressure (1013 mb), and gas mix (normal N2/O2 ratio) but illuminated with a Mars-normal UV-VIS-NIR spectrum were reduced by over 99.9% after 30 sec exposure to Mars-normal UV fluence rates. However, it required at least 15 min of Mars-normal UV exposure to reduce bacterial populations on aluminum coupons to non-recoverable levels. These results were duplicated when bacteria were exposed to Mars-normal environments of temperature (-10 degrees C), pressure (8.5 mb), gas composition (pure CO2), and UV fluence rates. In other experiments, results indicated that the gas composition of the atmosphere and the temperature of the bacterial monolayers at the time of Mars UV exposure had no effects on the survival of bacterial endospores. But Mars-normal pressures (8.5 mb) were found to reduce survival by approximately 20-35% compared to Earth-normal pressures (1013 mb). The primary implications of these results are (a) that greater than 99.9% of bacterial populations on sun-exposed surfaces of spacecraft are likely to be inactivated within a few tens of seconds to a few minutes on the surface of Mars, and (b) that within a single Mars day under clear-sky conditions bacterial populations on sun-exposed surfaces of spacecraft will be sterilized. Furthermore, these results suggest that the high UV fluence rates on the martian surface can be an important resource in minimizing the forward contamination of Mars. c2003 Elsevier Inc. All rights reserved.

Bacillus subtilis/growth & development/physiology/↗
NASA NTRS2020

Prokaryotic and Fungal Characterization of the Facilities Used to Assemble, Test, and Launch the OSIRIS-REx Spacecraft

To characterize the ATLO (Assembly, Test, and Launch Operations) environment of the OSIRIS-REx spacecraft, we analyzed 17 aluminum witness foils and two blanks for bacterial, archaeal, fungal, and arthropod DNA. Under NASA’s Planetary Protection guidelines, OSIRIS-REx is a Category II outbound, Category V unrestricted sample return mission. As a result, it has no bioburden restrictions. However, the mission does have strict organic contamination requirements to achieve its primary objective of returning pristine carbonaceous asteroid regolith to Earth. Its target, near-Earth asteroid (101955) Bennu, is likely to contain organic compounds that are biologically available. Therefore, it is useful to understand what organisms were present during ATLO as part of the larger contamination knowledge effort—even though it is unlikely that any of the organisms will survive the multi-year deep space journey. Even though these samples of opportunity were not collected or preserved for DNA analysis, we successfully amplified bacterial and archaeal DNA (16S rRNA gene) from 16 of the 17 witness foils containing as few as 7 ± 3 cells per sample. Fungal DNA (ITS1) was detected in 12 of the 17 witness foils. Despite observing arthropods in some of the ATLO facilities, arthropod DNA (COI gene) was not detected. We observed 1,009 bacterial and archaeal sOTUs (sub-operational taxonomic units, 100% unique) and 167 fungal sOTUs across all of our samples (25–84 sOTUs per sample). The most abundant bacterial sOTU belonged to the genus Bacillus. This sOTU was present in blanks and may represent contamination during sample handling or storage. The sample collected from inside the fairing just prior to launch contained several unique bacterial and fungal sOTUs that describe previously uncharacterized potential for contamination during the final phase of ATLO. Additionally, fungal richness (number of sOTUs) negatively correlates with the number of carbon-bearing particles detected on samples. The total number of fungal sequences positively correlates with total amino acid concentration. These results demonstrate that it is possible to use samples of opportunity to characterize the microbiology of low-biomass environments while also revealing the limitations imposed by sample collection and preservation methods not specifically designed with biology in mind.

Aaron B. Regberg↗
NASA NTRS1994

Influence of antiorthostatic suspension on resistance to murine Listeria monocytogenes infection

The present study was designed to evaluate the influence of antiorthostatic suspension, a ground-based modeling system employed to simulate certain aspects of weightlessness that occur during space flight, on the capacity of mice to resist infection with the facultative intracellular bacterial pathogen Listeria monocytogenes. Female BDF1 mice were suspended by the tail in the orthostatic or antiorthostatic position and were infected with a sublethal dose of virulent L. monocytogenes at various times during the suspension. It was found that suspension did not influence the kinetics of bacterial growth in vivo if the infection was started concurrently with the suspension. However, mice that were antiorthostatically suspended 2, 4, or 7 days before the onset of infection exhibited an enhanced capacity to eliminate the challenge infection. Suspending mice on day 2 of the infection did not alter the kinetics of bacterial growth. Finally, the enhancement of resistance to the primary Listeria infection was accompanied by failure of the mice to generate long-term protective immunological memory to the challenge organism. Collectively, these results indicate that the stress of antiorthostatic suspension can influence the capacity of mice to resist bacterial infection.

NASA Discipline Regulatory Physiology↗
NASA NTRS1977

Application of firefly luciferase assay for adenosine triphosphate (ATP) to antimicrobial drug sensitivity testing

The development of a rapid method for determining microbial susceptibilities to antibiotics using the firefly luciferase assay for adenosine triphosphate (ATP) is documented. The reduction of bacterial ATP by an antimicrobial agent was determined to be a valid measure of drug effect in most cases. The effect of 12 antibiotics on 8 different bacterial species gave a 94 percent correlation with the standard Kirby-Buer-Agar disc diffusion method. A 93 percent correlation was obtained when the ATP assay method was applied directly to 50 urine specimens from patients with urinary tract infections. Urine samples were centrifuged first to that bacterial pellets could be suspended in broth. No primary isolation or subculturing was required. Mixed cultures in which one species was predominant gave accurate results for the most abundant organism. Since the method is based on an increase in bacterial ATP with time, the presence of leukocytes did not interfere with the interpretation of results. Both the incubation procedure and the ATP assays are compatible with automation.

Picciolo, G. L.↗
NASA NTRS1992

Light scattering by marine heterotrophic bacteria

Mie theory is applied to estimate scattering by polydispersions of marine heterotrophic bacteria, and a simple expression is derived for the bacterial scattering coefficient. The error incurred in deriving bacterial optical properties by use of the van de Hulst approximations is computed. The scattering properties of natural bacterial assemblages in three marine environments, Georges Bank, Northeast Channel, and Sargasso Sea, are assessed by applying Mie theory to field data on bacterial size and abundance. Results are used to examine the potential contribution of bacteria to the scattering properties of seawater. The utility of using pigment data to predict the magnitude of scattering by bacteria is discussed.

Ulloa, Osvaldo↗
NASA NTRS1999

Effects of Space Flight, Clinorotation, and Centrifugation on the Growth and Metabolism of Escherichia Coli

Previous experiments have shown that space flight stimulates bacterial growth and metabolism. An explanation for these results is proposed, which may eventually lead to improved terrestrial pharmaceutical production efficiency. It is hypothesized that inertial acceleration affects bacterial growth and metabolism by altering the transport phenomena in the cells external fluid environment. It is believed that this occurs indirectly through changes in the sedimentation rate acting on the bacteria and buoyancy-driven convection acting on their excreted by-products. Experiments over a broad range of accelerations consistently supported this theory. Experiments at I g indicated that higher concentrations of excreted by products surrounding bacterial cells result in a shorter lag phase. Nineteen additional experiments simulated 0 g and 0.5 g using a clinostat, and achieved 50 g, 180 g, and 400 g using a centrifuge. These experiments showed that final cell density is inversely related to the level of acceleration. The experiments also consistently showed that acceleration affects the length of the lag phase in a non-monotonic, yet predictable, manner. Additional data indicated that E. coli metabolize glucose less efficiently at hypergravity, and more efficiently at hypogravity. A space-flight experiment was also performed. Samples on orbit had a statistically significant higher final cell density and more efficient metabolism than did ground controls. These results. which were similar to simulations of 0 g using a clinostat, support the theory that gravity only affects bacterial growth and metabolism indirectly, through changes in the bacteria's fluid environment.

Brown, Robert B.↗
NASA NTRS2004

Microbial Characterization During the Early Habitation of the International Space Station

An evaluation of the microbiota from air, water, and surface samples provided a baseline of microbial characterization onboard the International Space Station (ISS) to gain insight into bacterial and fungal contamination during the initial stages of construction and habitation. Using 16S genetic sequencing and rep-PCR, 63 bacterial strains were isolated for identification and fingerprinted for microbial tracking. Of the bacterial strains that were isolated and fingerprinted, 19 displayed similarity to each other. The use of these molecular tools allowed for the identification of bacteria not previously identified using automated biochemical analysis and provided a clear indication of the source of several ISS contaminants. Strains of Bradyrhizobium and Sphingomonas unable to be identified using sequencing were identified by comparison of rep-PCR DNA fingerprints. Distinct DNA fingerprints for several strains of Methylobacterium provided a clear indication of the source of an ISS water supply contaminant. Fungal and bacterial data acquired during monitoring do not suggest there is a current microbial hazard to the spacecraft, nor does any trend indicate a potential health risk. Previous spacecraft environmental analysis indicated that microbial contamination will increase with time and will require continued surveillance. Copyright 2004 Springer-Verlag.

Fungi/genetics↗
NASA NTRS2005

Keeping the Air Clean and Safe: An Anthrax Smoke Detector

Scientists at work in the Planetary Protection division at NASA s Jet Propulsion Laboratory (JPL) sterilize everything before blasting it to the Red Planet. They take great pains to ensure that all spacecraft are void of bacterial life, especially the microscopic bacteria that can live hundreds of years in their spore states. No one is quite sure what Earthly germs would do on Mars, but scientists agree that it is safest to keep the Martian terrain as undisturbed as possible. Errant Earth germs would also render useless the instruments placed on exploration rovers to look for signs of life, as the life that they registered would be life that came with them from Earth. A team at JPL, headed by Dr. Adrian Ponce, developed a bacterial spore-detection system that uses a simple and robust chemical reaction that visually alerts Planetary Protection crews. It is a simple air filter that traps micron-sized bacterial spores and then submits them to the chemical reaction. When the solution is then viewed under an ultraviolet light, the mixture will glow green if it is contaminated by bacteria. Scientists can then return to the scrubbing and cleaning stages of the sterilization process to remove these harmful bacteria. The detection system is the space-bound equivalent of having your hands checked for cleanliness before being allowed to the table; and although intended to keep terrestrial germs from space, this technology has awesome applications here on Mother Earth. The bacterial spore-detection unit can recognize anthrax and other harmful, spore-forming bacteria and alert people of the impending danger. As evidenced in the anthrax mailings of fall 2001 in the United States, the first sign of anthrax exposure was when people experienced flu-like symptoms, which unfortunately, can take as much as a week to develop after contamination. Anthrax cost 5 people their lives and infected 19 others; and the threat of bioterrorism became a routine concern, with new threats popping up nearly everyday. The attacks threatened the safety that so many Americans took for granted, as the very air that people breathed became suspect. Any building with a circulation system, where large groups congregate, was now a potential target.

Source record↗
NASA NTRS2008

Gastrointestinal Physiology During Head Down Tilt Bedrest in Human Subjects

Introduction: Gastrointestinal (GI) motility plays a key role in the physiology and function of the GI tract. It directly affects absorption of medications and nutrients taken by mouth, in addition to indirectly altering GI physiology by way of changes in the microfloral composition and biochemistry of the GI tract. Astronauts have reported nausea, loss of appetite and constipation during space flight all of which indicate a reduction in GI motility and function similar to the one seen in chronic bed rest patients. The purpose of this study is to determine GI motility and bacterial proliferation during -6 degree head down tilt bed rest (HTD). Methods: Healthy male and female subjects between the ages of 25-40 participated in a 60 day HTD study protocol. GI transit time (GITT) was determined using lactulose breath hydrogen test and bacterial overgrowth was measured using glucose breath hydrogen test. H. Pylori colonization was determined using C13-urea breath test (UBIT#). All three tests were conducted on 9 days before HDT, and repeated on HDT days 2, 28, 58, and again on day 7 after HDT. Results: GITT increased during HTD compared to the respective ambulatory control values; GITT was significantly lower on day 7 after HTD. A concomitant increase in bacterial colonization was also noticed during HDT starting after approximately 28 days of HDT. However, H. Pylori proliferation was not recorded during HDT as indicated by UBIT#. Conclusion: GITT significantly decreased during HDT with a concomitant increase in the proliferation of GI bacterial flora but not H. pylori.

Vaksman, Z.↗
NASA NTRS2009

Efficacy of Various Chemical Disinfectants on Biofilms Formed in Spacecraft Potable Water System Component

As the provision of potable water is critical for successful habitation of the International Space Station (ISS), life support systems were installed in December 2008 to recycle both humidity from the atmosphere and urine to conserve available water in the vehicle. Pre-consumption testing from the dispensing needle at the Potable Water Dispenser (PWD) indicated that bacterial concentrations exceeded the current ISS specifications of 50 colony forming units (CFU) per ml. Subsequent investigations revealed that a corrugated stainless steel flex hose upstream of the dispensing needle in the PWD was filled with non-sterile water and left at room temperature for over one month before launch. To simulate biofilm formation that was suspected in the flight system, sterile flex hoses were seeded with a consortium of bacterial isolates previously recovered from other ISS water systems, which included Ralstonia pickettii, Burkholderia multivorans, Caulobacter vibrioides., and Cupriavidus pauculus. After 5 days of incubation, these hoses were challenged with various chemical disinfectants including hydrogen peroxide, colloidal silver, and buffered pH solutions to determine the ability of the disinfectants to decrease and maintain bacterial concentrations below ISS specifications. Disinfection efficacy over time was measured by collecting daily heterotrophic plate counts following exposure to the disinfectants. A single flush with either 6% hydrogen peroxide solution or a mixture of 3% hydrogen peroxide and 400 ppb colloidal silver effectively reduced the bacterial concentrations to less than 1 CFU/ml for a period of up to 2 months. Testing results indicated that hydrogen peroxide and mixtures of hydrogen peroxide and colloidal silver have tremendous potential as alternative disinfectants for ISS water systems.

Wong, Willy↗
NASA NTRS2022

Going to Extremes: Architecting Holographic Microscopes for Extreme Environments

Bacterial life exists on earth in extreme environments. These are environments described by large temperature excur- sions, large pressure excursions, and large radiation excursions from the nominal conditions near sea level which are largely populated by humans. These extreme locales represent such places as the ocean ice, the briny pools of Death Valley and deep mines, the acidic hot springs of the High Sierra or Yellowstone, or even the clouds of our upper atmosphere. The preponderance of bacterial life in these extreme environments here on earth suggests that bacterial life might likely exist in the extreme environments of our own solar system, such as the icy moons of Europa or Enceladus. Thus, architecting instruments for detect- ing life in these extreme environments on earth builds confidence that we can architect such instruments for flight missions. In this paper, we discuss our experience with designing digital holo- graphic microscope instruments to enable detection of bacteria in several extreme environments. In particular we discuss three different instruments. The first is our field instrument which is a small, portable instrument for examination of remote sites. The second is submersible instrument which enables exploration of deep aquatic environments and is deployed on a ocean-going drone. The third is a balloon-borne instrument to examine the bacterial content of the upper atmosphere. We will provide a review of each instrument and discuss aspects of instrument engineering for each particular application.

Ramirez, Alex↗
NASA NTRS1973

Automatic instrument for chemical processing to detect microorganism in biological samples by measuring light reactions

An automated apparatus is reported for sequentially assaying urine samples for the presence of bacterial adenosine triphosphate (ATP) that comprises a rotary table which carries a plurality of sample containing vials and automatically dispenses fluid reagents into the vials preparatory to injecting a light producing luciferase-luciferin mixture into the samples. The device automatically measures the light produced in each urine sample by a bioluminescence reaction of the free bacterial adenosine triphosphate with the luciferase-luciferin mixture. The light measured is proportional to the concentration of bacterial adenosine triphosphate which, in turn, is proportional to the number of bacteria present in the respective urine sample.

Kelbaugh, B. N.↗
NASA NTRS1975

A rapid method for the determination of microbial susceptibility using the firefly luciferase assay for adenosine triphosphate (ATP)

Luciferase assay for adenosine triphosphate (ATP) was optimized for pure bacteria in broth in order to evaluate if changes in bacterial ATP content could be used as a rapid measure of antibiotic effect on microorganisms. Broth cultures of log phase bacteria were incubated at 310 K (37 C) for 2.5 hours at antimicrobial concentrations which resulted in the best discrimination between sensitive and resistant strains. Eighty-seven strains of 11 bacterial species were studied for their susceptibility to 12 commonly used antimicrobial agents: ampicillin, Penicillin G, nafcillin, carbenicillin, cephalothin, tetracycline, erythromycin, clindamycin, gentamicin, nitrofurantoin, colistin, and chloramplenicol. The major advantage of the ATP system over existing methods of rapid microbial susceptibility testing is that the assay can be made specific for bacterial ATP.

Vellend, H.↗