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NASA NTRS1988

Does iron inhibit cryptoendolithic microbial communities?

Photosynthetic activity of three cryptoendolithic microbial communities was studied under controlled conditions in the laboratory. In two of these communities, the dominant organisms were lichens, collected from Linnaeus Terrace and from Battleship Promontory. The third community, dominated by cyanobacteria, was collected from Battleship Promontory. Both sites are in the ice-free valleys of southern Victoria Land. Previous efforts have shown how physical conditions can influence metabolic activity in endolithic communities (Kappen and Friedmann 1983; Kappen, Friedmann, and Garty 1981; Vestal, Federle, and Friedmann 1984). Biological activity can also be strongly influenced by the chemical environment. Inorganic nutrients such as nitrate, ammonia, and phosphate are often limiting factors, so their effects on photosynthetic carbon-14 bicarbonate incorporation were investigated. Iron and manganese are two metals present in Linnaeus Terrace and Battleship Promontory sandstones, and their effects on photosynthesis were also studied. The results may add to our understanding of biogeochemical interactions within this unique microbial community.

Non-NASA Center↗

NASA NTRS1989

Effect of iodine disinfection products on higher plants

Iodine is used to disinfect potable water on United States spacecraft. Iodinated potable water will likely be used to grow plants in space. Little is known about the effects of iodine disinfection products on plants. Seeds of select higher plants were germinated in water iodinated using the Shuttle Microbial Check Valve, and water to which measured amounts of iodine was added. Percent germination was decreased in seeds of most species germinated in iodinated water. Beans were most affected. Germination rates, determined from germination half-times, were decreased for beans germinated in iodinated water, and water to which iodide was added. Development was retarded and rootlets were conspicuously absent in bean and several other plant species germinated in iodinated water. Iodide alone did not elicit these responses. Clearly iodine disinfection products can affect higher plants. These effects must be carefully considered for plant experimentation and cultivation in space, and in design and testing of closed environmental life support systems.

Janik, D.↗

NASA NTRSDate not supplied

VEG-05 Tomato Crop Testing on the International Space Station

Production of fresh, nutritious, and tasty produce for astronauts during spaceflight may provide health-promoting, bioavailable nutrients, enhance the dietary experience, and reduce menu fatigue as we move into longer-duration missions. Growing and caring for plants may also reduce the psychological stresses associated with spaceflight and enhance connection to Earth. A diversity of crops will be required to provide nutrition, variety, and resiliency, however requirements for consistent growth under spaceflight environmental conditions remain unclear. VEG-05 is part of a series of experiments with pick-and-eat salad crops to better define best practices for crop production in space. VEG-05 and predecessor experiments VEG-04A and VEG-04B, grew salad crops in the Veggie vegetable production facilities on the International Space Station using different lighting treatments. In VEG-05 we grew ‘Red Robin’ dwarf cherry tomatoes under two different red: blue lighting spectra. Light can impact the growth habit, yield, nutritional composition, microbial levels, and even flavor attributes within crops, and our goal was to assess these characteristics in ‘Red Robin’ tomatoes during VEG-05. Considerable pre-flight verification testing was performed prior to launch in Nov. 2022. Prior to the flight and ground experiments, lighting in both Veggie units on ISS was measured and lights were standardized between flight and ground hardware. VEG-05 flight operations ran between December 2022 and March 2023, with a ground control initially 48 hours delayed. Due to environmental challenges of very low humidity during the first week of the experiment, seed germination was low for both flight and ground plants. The flight experiment ultimately had 4 - 5 plants per treatment out of the planned 6 plants, but the initial ground control had only three plants in one treatment and none in the other, so this ground control was restarted at the beginning of Feb. 2023 and ran through May, with successful growth of all 12 plants. Both flight and ground control ran 100 days, with harvests of fruit at day 83, day 90, and day 100. Flight plants had uneven growth, and following the early drying events, excess water was frequently observed, which led to a variety of plant stress responses including uneven plant growth, excess adventitious root formation, flower and fruit abortion, and visible microbial growth. In total, from the five surviving red-rich lighted plants, only 5 ripe fruit were produced, and from the four surviving blue-rich lighted plants, 10 fruit were produced with only 6 of these ripe by day 100. Because of the small fruit number and the unsatisfactory growth, crew members were not allowed to consume the tomatoes, and all fruit, as well as large branches with leaves, samples of the adventitious roots, two plant rooting pillows from each treatment, microbial sampling swabs, and some water samples were returned for analysis. Because of the small sample sizes and factors affecting growth on the ISS, objectives of assessing light quality effect (red: blue light treatments) will not be achieved. Revised objectives of this study include to compare stressed flight plants with normal ground plants to determine the impact of plant overwatering stress in space on food safety and the plant microbial community, to determine nutrient content changes in fruit and leaves from stressed plants, and to evaluate stress metabolism changes in returned tissue by transcriptomic analysis. Postflight analysis is underway with the following analyses being conducted: A. culturable microbiology and food safety as well as molecular microbial community analysis of 1. ripe fruit, 2. leaves, stems, and adventitious roots, 3. pillow components (roots, wicks, and substrates), 4. swabs, and 5. water samples from root mats before and after growth. B. transcriptomics of leaf tissue and adventitious roots, and C. elemental analysis of leaf tissue. If sufficient tissue remains elemental analyses will also be conducted on fruit. While not generating the desired information on spaceflight growth responses of healthy crops, our team is hopeful that these analyses will shed light on tomato responses to stress in this environment as plant overwatering stress is a mission-relevant condition that could occur in future space crop growth systems. This research was co-funded by the Human Research Program and Space Biology (MTL#1075) in the ILSRA 2015 NRA call.

Gioia D. Massa↗

NASA NTRS2005

Planetary Protection Issues in the Human Exploration of Mars

This workshop report, long delayed, is the first 21st century contribution to what will likely be a series of reports examining the effects of human exploration on the overall scientific study of Mars. The considerations of human-associated microbial contamination were last studied in a 1990 workshop ("Planetary Protection Issues and Future Mars Missions," NASA CP-10086, 1991), but the timing of that workshop allowed neither a careful examination of the full range of issues, nor an appreciation for the Mars that has been revealed by the Mars Global Surveyor and Mars Pathfinder missions. Future workshops will also have the advantage of Mars Odyssey, the Mars Exploration Rover missions, and ESA's Mars Express, but the Pingree Park workshop reported here had both the NCR's (1992) concern that "Missions carrying humans to Mars will contaminate the planet" and over a decade of careful study of human exploration objectives to guide them and to reconcile. A daunting challenge, and one that is not going to be simple (as the working title of this meeting, "When Ecologies Collide?" might suggest), it is clear that the planetary protection issues will have to be addressed to enable human explorers to safely and competently extend out knowledge about Mars, and its potential as a home for life whether martian or human.

Criswell, Marvin E.↗

NASA NTRS2008

Purifying Nucleic Acids from Samples of Extremely Low Biomass

A new method is able to circumvent the bias to which one commercial DNA extraction method falls prey with regard to the lysing of certain types of microbial cells, resulting in a truncated spectrum of microbial diversity. By prefacing the protocol with glass-bead-beating agitation (mechanically lysing a much more encompassing array of cell types and spores), the resulting microbial diversity detection is greatly enhanced. In preliminary studies, a commercially available automated DNA extraction method is effective at delivering total DNA yield, but only the non-hardy members of the bacterial bisque were represented in clone libraries, suggesting that this method was ineffective at lysing the hardier cell types. To circumvent such a bias in cells, yet another extraction method was devised. In this technique, samples are first subjected to a stringent bead-beating step, and then are processed via standard protocols. Prior to being loaded into extraction vials, samples are placed in micro-centrifuge bead tubes containing 50 micro-L of commercially produced lysis solution. After inverting several times, tubes are agitated at maximum speed for two minutes. Following agitation, tubes are centrifuged at 10,000 x g for one minute. At this time, the aqueous volumes are removed from the bead tubes and are loaded into extraction vials to be further processed via extraction regime. The new method couples two independent methodologies in such as way as to yield the highest concentration of PCR-amplifiable DNA with consistent and reproducible results and with the most accurate and encompassing report of species richness.

La Duc, Myron↗

NASA NTRS2004

Microbial Response to Microgravity and Other Low Shear Environments

Microbial existence and survival requires the ability to sense and respond to environmental changes, including changes in physical forces. This is because microbes inhabit an amazingly diverse range of ecological niches and therefore must constantly adapt to a wide variety of changing environmental conditions, including alterations in temperature, pH, nutrient availability, oxygen levels, and osmotic pressure gradients. Microbes sense their environment through a variety of sensors and receptors which serve to integrate the different signals into the appropriate cellular response(s) that is optimal for survival. While numerous environmental stimuli have been examined for their effect on microorganisms, effects due to changes in mechanical and/or physical forces are also becoming increasingly apparent. Recently, several important studies have demonstrated a key role for microgravity and the low fluid shear dynamics associated with microgravity in the regulation of microbial gene expression, physiology and pathogenesis. The mechanosensory response of microorganisms to these environmental signals, which are relevant to those encountered during microbial life cycles on Earth, may provide insight into their adaptations to physiologically relevant conditions and may ultimately lead to eludicidation of the mechanisms important for mechanosensory transduction in living cells. This review summarizes the recent and potential future research trends aimed at understanding the effect of changes in mechanical forces that occur in microgravity and other low shear environments on different microbial parameters. The results of these studies provide an important step towards understanding how microbes integrate information from multiple mechanical stimuli to an appropriate physiological response.

Nickerson, C.↗

NASA NTRS1973

Effects of space vacuum and solar ultraviolet irradiation (254 nanometers) on the colony forming ability of Bacillus subtilis spores

Bacillus subtilis spores are highly resistant to harsh environments. Therefore, in the Apollo 16 Microbial Response to Space Environment Experiment (M191), these spores were exposed to space vacuum or solar ultraviolet irradiation, or both, to estimate the change of survival for terrestrial organisms in space. The survival of the spores was determined in terms of colony-forming ability. Comparison of the flight results with results of simulation experiments on earth applying high vacuum or ultraviolet irradiation, or both, revealed no remarkable difference. Simultaneous exposure to both these space factors resulted in a synergistic effect (that is, an ultraviolet supersensitivity). Therefore, the change of survival in space is assumed to depend on the degree of protection against solar ultraviolet irradiation.

Buecker, H.↗

NASA NTRSDate not supplied

Retrospectives: Current State of Knowledge on the Intersection of Spaceflight Stressors and Microbial Risks to Crew and Craft

OVERVIEW The spaceflight environment has several unique stressors that affect the health of both the crew and the spacecraft. An area of continued, albeit incomplete, study is the interaction of these stressors on microbial populations inherent to both astronauts and spacecraft surfaces and systems. A primary concern is the potential for the spaceflight environment to perturb the phenotype of these populations towards negative outcomes for crew and craft. In order to effectively mitigate these potential risks, they must first be characterized. We performed a retrospective literature analysis to assess the current state of knowledge regarding the affects of ionizing radiation and elevated CO2 on relevant microbial populations. The results of these retrospectives will guide next steps in the decisions of what (if any) further studies should be pursued and to guide decisions of the need for countermeasures. STRESSORS Ionizing radiation. The health risk involved with increased exposure to cosmic radiation has been studied in crew for 35+ years, with human health and cancer risk being the main focus. However, space radiation could also affect both the resident microorganisms aboard the ISS and the normal, healthy astronaut microbiomes that are of direct concern for crew health. A retrospective review of over 250 publications was accomplished looking at the impact of cumulative ionizing radiation doses lower than 3 Gy (chronic or acute) on microbial populations. Elevated CO2. The health risk involved with elevated atmospheric CO2 in spacecraft, primarily focusing on human toxicological risks, is understudied. The current Spaceflight Maximum Allowance Concentration for 24-hour average CO2 is 0.4% (3 mm Hg), which is significantly higher than terrestrial levels (0.04%). Whether these elevated ambient CO2 levels aboard spacecraft influence the diversity and phenotypic responses of the resident microbial communities from both the spacecraft environment (air, surface, water) and crew members (gut, nasal, skin microbiomes) is not known. A retrospective review was accomplished looking at the impact of chronic CO2 exposure up to 0.7% (5 mm Hg) for up to 6 months and acute exposure up to 2.6% (20 mm Hg) for up to 24 hours. CONCLUSIONS: MICROBIOME OF THE BUILT ENVIRONMENT The microbiome of the built spacecraft environment has been sampled consistently over the course of human spaceflight and significant advancements have been made in identifying microbial populations on the ISS. The dominant source of microbes on spacecraft surfaces are human-derived. Once in the spacecraft built environment, the extreme environment selects for features that enhance survival. While efforts to understand potential antibiotic resistance and pathogenicity of ISS isolates is robust, there is little to no understanding of which spaceflight environmental stressors, to include ionizing radiation or elevated CO2, drive the evolutionary trajectory of spacecraft-associated microbial populations. CONCLUSIONS: MICROBE-HOST INTERACTIONS The host-microbiome field has emerged as an important factor in human health on Earth as well in spaceflight. The field is struggling with the complexity of the system under investigation as there is substantial taxonomic and functional heterogeneity in these communities, making it difficult to establish clear stimulus-response dynamics. Taxonomic characterization is the norm; however, the functional role of each community member is key to linking environmental perturbations to potential dysbiosis. For both ionizing radiation and elevated CO2, the likely target of the perturbation is the host tissue, not the microbes themselves.. Any resulting changes to the microbial community composition and/or function is likely a result of adapting to those changes in the host physiology. RECOMMENDATIONS Emphasize functional characterization as opposed to taxonomic characterization of microbial communities. Increase the number of investigations using chronic, spaceflight-relevant doses of ionizing radiation. MoBE studies should move away from observational studies towards predictive modeling of community dynamics. Continue to develop scale-down models, such as tissues-on-a-chip & defined microbial communities. Focus on the crew response to elevated CO2 over MoBE considerations. Assess how direct contact with the hypercapnic environment affects skin microbiome dynamics.

retrospective↗

NASA NTRSDate not supplied

Retrospectives: Intersection of Spaceflight Stressors and Microbial Risk to Crew and Craft

OVERVIEW The spaceflight environment has several unique stressors that affect the health of both the crew and the spacecraft. An area of continued, albeit incomplete, study is the interaction of these stressors on microbial populations inherent to both astronauts and spacecraft surfaces and systems. A primary concern is the potential for the spaceflight environment to perturb the phenotype of these populations towards negative outcomes for crew and craft. In order to effectively mitigate these potential risks, they must first be characterized. We performed a retrospective literature analysis to assess the current state of knowledge regarding the affects of ionizing radiation and elevated CO2 on relevant microbial populations. The results of these retrospectives will guide next steps in the decisions of what (if any) further studies should be pursued and to guide decisions of the need for countermeasures. STRESSORS Ionizing radiation. The health risk involved with increased exposure to cosmic radiation has been studied in crew for 35+ years, with human health and cancer risk being the main focus. However, space radiation could also affect both the resident microorganisms aboard the ISS and the normal, healthy astronaut microbiomes that are of direct concern for crew health. A retrospective review of over 250 publications was accomplished looking at the impact of cumulative ionizing radiation doses lower than 3 Gy (chronic or acute) on microbial populations. Elevated CO2. The health risk involved with elevated atmospheric CO2 in spacecraft, primarily focusing on human toxicological risks, is understudied. The current Spaceflight Maximum Allowance Concentration for 24-hour average CO2 is 0.4% (3 mm Hg), which is significantly higher than terrestrial levels (0.04%). Whether these elevated ambient CO2 levels aboard spacecraft influence the diversity and phenotypic responses of the resident microbial communities from both the spacecraft environment (air, surface, water) and crew members (gut, nasal,skin microbiomes) is not known. A retrospective review was accomplished looking at the impact of chronic CO2 exposure up to 0.7% (5 mm Hg) for up to 6 months and acute exposure up to 2.6% (20 mm Hg) for up to 24 hours. CONCLUSIONS: MICROBIOME OF THE BUILT ENVIRONMENT The microbiome of the built spacecraft environment has been sampled consistently over the course of human spaceflight and significant advancements have been made in identifying microbial populations on the ISS. The dominant source of microbes on spacecraft surfaces are human-derived. Once in the spacecraft built environment,the extreme environment selects for features that enhance survival. While efforts to understand potential antibiotic resistance and pathogenicity of ISS isolates is robust, there is little to no understanding of which spaceflight environmental stressors, to include ionizing radiation or elevated CO2, drive the evolutionary trajectory of spacecraft-associated microbial populations. CONCLUSIONS: MICROBE-HOST INTERACTIONS The host-microbiome field has emerged as an important factor in human health on Earth as well in spaceflight. The field is struggling with the complexity of the system under investigation as there is substantial taxonomic and functional heterogeneity in these communities, making it difficult to establish clear stimulus-response dynamics.Taxonomic characterization is the norm; however, the functional role of each community member is key to linking environmental perturbations to potential dysbiosis. For both ionizing radiation and elevated CO2, the likely target of the perturbation is the host tissue, not the microbes themselves.. Any resulting changes to the microbial community composition and/or function is likely a result of adapting to those changes in the host physiology. RECOMMENDATIONS Emphasize functional characterization as opposed to taxonomic characterization of microbial communities.Increase the number of investigations using chronic, spaceflight-relevant doses of ionizing radiation. MoBE studies should move away from observational studies towards predictive modeling of community dynamics. Continue to develop scale-down models, such as tissues-on-a-chip & defined microbial communities. Focus on the crew response to elevated CO2 over MoBE considerations. Assess how direct contact with the hypercapnic environment affects skin microbiome dynamics.

Countermeasures↗

NASA NTRSDate not supplied

Endogenous Microbial Survival in Brewed Tea

Loose-leaf bagged tea is a commonly requested beverage item that comprises up to 7% of the microbiological samples from the space food systems. As loose-leaf tea blends often contain herbs and spices that frequently have high microbial loads, they have a high failure rate as defined by the microbiological standards outlined in NASA-STD-3001, which are more stringent than the limits set for industry. Between April 2019 and September 2022, 54.8% of loose-leaf teas submitted for microbiological testing have failed, necessitating the evaluation of a variety of brands and lot numbers of each requested tea type to meet crew preference requests, which are typically specific, resulting in excess labor and material costs to provide a single product for spaceflight consumption. Attempts to identify specific brands or ingredients that are less likely to produce a failure have been unsuccessful, as to date, no trends in those measures have been identified. We have, however, noticed a trend in types of teas (spiced and herbal) which are more likely to fail. Of additional concern, hot water available for brewing tea on ISS is dispensed at a lower temperature than the CDC recommended brewing temperature. In a study we previously reported, we found that that brewing water temperature may not have a significant impact on the number of aerobic bacteria in chamomile tea, as there were no significant differences in the total microbial load between tea brewed with boiling, ISS-like, or room temperature waters. It did appear that ISS temperature water was similarly effective to boiling water against a pathogenic bacterial species. In this study, we aim to assess whether the total number of aerobic bacteria of other high-fail-rate tea types is similarly unaffected when brewing tea in room temperature or boiling water. Data from this study and the previous study, as well as additional analysis of every tea product that has been tested as part of the normal food system since April 2019, will be used to determine the expected typical microbial load for loose-leaf teas, which we will compare to existing industry limits so that we can recommend a new microbiological limit for loose-leaf teas that accurately reflects the true risk of consuming brewed teas in spaceflight.

space flight food↗

NASA NTRS1977

Planetary quarantine

Those areas of future missions which will be impacted by planetary quarantine (PQ) constraints were identified. The specific objectives for this reporting period were (1) to perform an analysis of the effects of PQ on an outer planet atmospheric probe, and (2) to prepare a quantitative illustration of spacecraft microbial reduction resulting from exposure to space environments. The Jupiter Orbiter Probe mission was used as a model for both of these efforts.

Source record↗

NASA NTRS2015

Space Biophysics: Accomplishments, Trends, Challenges

Physics and biology are inextricably linked. All the chemical and biological processes of life are dutifully bound to follow the rules and laws of physics. In space, these physical laws seem to turn on their head and biological systems, from microbes to humans, adapt and evolve in myriad ways to cope with the changed physical influences of the space environment. Gravity is the most prominent change in space that influences biology. In microgravity, the physical processes of sedimentation, density-driven convective flow, influence of surface tension and fluid pressure profoundly influence biology at the molecular and cellular level as well as at the whole-body level. Gravity sensing mechanisms are altered, structural and functional components of biology (such as bone and muscle) are reduced and changes in the way fluids and gasses behave also drive the way microbial systems and biofilms grow as well as the way plants and animals adapt. The radiation environment also effects life in space. Solar particle events and high energy cosmic radiation can cause serious damage to DNA and other biomolecules. The results can cause mutation, cellular damage or death, leading to health consequences of acute radiation damage or long-term health consequences such as increased cancer risk. Space Biophysics is the study and utilization of physical changes in space that cause changes in biological systems. The unique physical environment in space has been used successfully to grow high-quality protein crystals and 3D tissue cultures that could not be grown in the presence of unidirectional gravitational acceleration here on Earth. All biological processes that change in space have their root in a biophysical alteration due to microgravity and/or the radiation environment of space. In order to fully-understand the risks to human health in space and to fully-understand how humans, plants, animals and microbes can safely and effectively travel and eventually live for long periods beyond the protective environment of Earth, the biophysical properties underlying these changes must be studied, characterized and understood. This lecture reviews the current state of NASA biophysics research accomplishments and identifies future trends and challenges for biophysics research on the International Space Station and beyond.

Space Biophysics: Accomplishments↗

NASA NTRSDate not supplied

Hydrogen Peroxide as a Method for Bioburden Reduction in Facilities with Strict Materials Requirements.

The cleanrooms used to curate NASA’s Astromaterials samples are carefully monitored for particulate and inorganic contamination. The clean labs also have a very limited set of acceptable materials and cleaning agents to further minimize the potential for contamination. Labs are cleaned primarily with isopropyl alcohol. Astromaterials samples are handled with tools made of stainless steel (304 or 316), Teflon, or aluminum alloy (6061). Although our current collections are not particularly susceptible to biological alteration or organic contamination, this will not be the case for new collections from the OSIRIS-REx mission, Hayabusa2, and from Mars Sample Return. Therefore, it is necessary to develop and test methods to reduce the bioburden in astromaterials cleanrooms without introducing unwanted contaminants. We will report on the results of three case studies where 7.5 wt% hydrogen peroxide was prepared from a stock solution of ultrapure 30 wt% hydrogen peroxide (JT Baker) using curation-grade ultrapure water. We followed CDC (Center for Disease Control) guidelines for using hydrogen peroxide as a high level disinfectant. This solution was used to clean a glovebox prior to processing Apollo samples, as well as surfaces in the Antarctic meteorite processing lab and Stardust lab after facilities monitoring indicated an unwanted increase in bioburden. In all three instances, the culturable bioburden was significantly reduced after a 30 min. exposure to the 7.5% hydrogen peroxide solution without a corresponding increase in inorganic or organic contamination. We observed 77 to 100% reductions in the bioburden recovery rate. In one case study, we also performed amplicon DNA sequencing on samples collected from the surfaces before and after cleaning. We observed a significant change in microbial community composition after peroxide cleaning. These results suggest that routine cleaning with hydrogen peroxide could be an effective way to control bioburden in astromaterials cleanrooms and other facilities with strict contamination control requirements.

A B Regberg↗

NASA NTRSDate not supplied

Hydrogen Peroxide as a Method for Bioburden Reduction in Facilities with Strict Materials Requirements

A B Regberg↗

NASA NTRSDate not supplied

American Society of Plant Biologists Plenary Symposium Overview Presentation

NASA’s Artemis program in collaboration with international space agencies, and various commercial partners, marks the return of humankind to the Moon. Unlike the Apollo lunar missions from fifty years ago, Artemis will set the stage for the continuous presence of humans on the Moon and pave a path for the journey to Mars and beyond. Plants will be an essential component of habitation systems that will enable humans to thrive on both the lunar and Mars surface, as well as space transit vehicles because of their nutritional and psychological benefits. Furthermore, plants will be valued in environmental control and life support systems because they generate oxygen, remove carbon dioxide, and recycle water and waste. However, an in-depth understanding of how plants and their associated microbial communities adapt to the harsh and confined environment of deep space is essential before they can be effectively used for long-duration space missions. This plenary symposium will address challenges and present potential solutions to growing plants in space. The four speakers will cover a broad range of topics, including mechanistic studies on fern resurgence after asteroid-triggered mass extinction events, artificial photosynthesis for space agriculture, and how the plant microbiome and an understanding of plant-pathogen dynamics in microgravity can guide crop production strategies in space.

Plant Space Biology↗

NASA NTRS1975

Effects of solar ultraviolet radiations on Bacillus subtilis spores and T-7 bacteriophage

Spores of Bacillus subtilis HA 101 and the DNA polymerase I-defective mutant HA 101 (59)F were exposed to selected wavelengths of solar ultraviolet light and space vacuum during the return of Apollo 16. In addition, coliphage T-7 suspensions were exposed to solar ultraviolet radiation as part of the Microbial Response to Space Environment Experiment. Optical filters were employed to provide different energy levels at wavelengths 254 nm and 280 nm. Dose-response curves for lethal and mutagenic effects were compared with ground-based data. A close parallel was observed between the results of solar radiation and ground tests with spores of the two strains. However, significantly greater inactivation of T-7 bacteriophage was observed after exposure to solar ultraviolet radiation.

Spizizen, J.↗

NASA NTRS2022

Examining the Effects of 4He Exposure on the Gut-Brain Axis

Beyond low earth orbit, space radiation poses significant risks to astronaut health. Previous studies have shown that the microbial composition of the gastrointestinal (GI) microbiome changes upon exposure to high linear energy transfer radiation. Interestingly, radiation-induced shifts in GI microbiota composition are linked to various neuropsychological disorders. Herein, we aimed to study changes in GI microbiota and behaviors of rats exposed to whole-body radiation (0, 5, or 25 cGy 4 He, 250 MeV/n) at approximately 6 months of age. Fecal samples were collected 24 hours prior to 4 He radiation and 24 hours and 7 days post-exposure for quantitative PCR analyses to assess fecal levels of spore-forming bacteria (SFB), Bifidobacterium, Lactobacillus, and Akkermansia. Rats were also tested in the social odor recognition memory (SORM) test at 7 days following 4 He exposure. A subset of rats was euthanized 90 minutes following completion of the SORM test, and GI tissue from small intestine to colon were prepared for examining overall histological changes and immunohistochemical staining for serotonin (5-HT). No notable pathological changes were observed in GI tissues. Akkermansia spp. and SFB were significantly decreased the 25 cGy group at 24 hours and 7 days post-exposure compared to pre-exposure, respectively. Bifidobacterium and Lactobacillus spp. showed no significant changes. 5-HT production was significantly higher in the proximal small intestine and the cecum in the 25 cGy group compared to the sham group. The 25 cGy group exhibited deficits in recognition in SORM testing at 7 days post-exposure. Taken together, these results suggest a connection between GI microbiome 3 composition, serotonin production, and neurobehavioral performance, and that this connection may be disrupted upon exposure to 25 cGy of 4 He ions

Carli B Jones↗

NASA NTRS1985

The cryptoendolithic microbial environment in the Antarctic cold desert: temperature variations in nature

In the Antarctic cold desert, cryptoendolithic microorganisms live under the surface of porous sandstone rocks. During the austral summer, the environment of the near-surface rock layers colonized by organisms is characterized by two kinds of temperature oscillations, both occurring across the freezing point. Low-frequency (diurnal) and large-amplitude (up to about 20 degrees C) oscillations on the sunlit surface of rocks result in a daily freeze-thaw cycle. This is a result of the diurnal changes in the sun altitude and angle with respect to the rock surface. The biological effect of this oscillation is the regulation of the onset and cessation of metabolic activity. The high-frequency (few minutes) oscillations occur only under certain weather conditions (sunny days with light winds) and are superimposed on the low-frequency oscillations. They are caused by the cooling effect of wind gusts on rock surfaces that are much warmer than ambient air temperatures. High-frequency oscillations result in a rapid freeze-thaw cycle on the surface, which, however, does not reach the microbial zone. These high-frequency freeze-thaw oscillations are probably the cause of the abiotic nature of the rock surface. Both oscillations seem to have an effect on rock weathering.

Cold Climate↗