Continued Environmental Microbiology Monitoring of the International Space Station (ISS) Veggie Unit Used for In-Flight, Crop-Based Food Systems
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The International Space Station is a closed environment where rotating sets of Crewmembers live and work. This environment is monitored to ensure occupants’ health and safety during their spaceflight residency by routine Environmental Health System (EHS) collection of microbial samples including air, surface, and water. The microbial samples are collected, enumerated, and analyzed quarterly to monitor on-board system contamination and potential risks to crew health. Quarterly monitoring of the microorganisms in the ISS environment supports crew safety and contributes to a large set of microbial concentration and diversity data. The current in-inflight microbial requirements were developed using this historical data collected by the routine environmental monitoring. These in-flight microbial requirements have been established to maintain the health and safety of the spacecraft environment. This study leverages quarterly operational EHS sampling by collecting additional microbial samples from the surface of the Veggie plant production system on ISS. These samples will yield microbial concentration and diversity that can be compared and analyzed with nominal surface samples from the vehicle. The data collected in this study will aid in the development of requirements for spaceflight-based food production systems. Continued surface sampling of the internal and external surfaces of the Veggie system, along with collaboration from both Johnson Space Center (JSC) & Kennedy Space Center (KSC) scientists studying the microbiome of the veggie-crop systems, will be implemented as part of the future development of crop-based food system requirements for the ISS and beyond.
We developed and tested a tool to collect aseptic samples during extravehicular activity or space walks. This tool can withstand the extreme temperature (-92 – 90 ˚C) and pressure variations without compromising the sterility of the collection device or the integrity of the sample. Results from ground testing the tool demonstrate that external surfaces of space suits are not sterile and that a wide variety of human associated bacteria and some fungi can survive at least seven hours of exposure to vacuum. These bacteria include non-spore forming organisms like Staphylococcus that are not normally considered extremophiles We plan to use this tool to characterize the exterior of the International Space Station. We expect the results of this work to guide the planetary protection requirements and contamination control strategy for crewed missions to Mars. This tool could also be used to monitor contamination associated with the Artemis missions to the moon or collect aseptic samples robotically in environments that are not suitable for human exploration.
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Crewmembers live and work in a closed environment that is monitored to ensure their health and safety. Quarterly monitoring of the microorganisms in the International Space Station (ISS) environment supports crew safety and contributes to a large set of environmental microbial data from the air, surface, and water samples that are collected. This study leverages quarterly operational Environmental Health System (EHS) sampling by collecting additional microbial samples from the surface of the station’s Veggie plant production system. Longer exploration missions may require spaceflight-based systems for growth of plants, and this investigation is expected to provide additional data to help establish requirements to protect these systems, plants, and crew, mitigating adverse microbial exposure.
NASA maintains nine separate cleanrooms at the Johnson Space Center to curate and preserve astromaterials samples. Routine microbial monitoring of the surfaces in these cleanrooms began in 20181. Until recently, materials compatibility requirements prevented monitoring airborne biological particles in all but one of these cleanrooms. New astromaterials collections from carbon rich asteroids are more susceptible to biological degradation than previous collections. Therefore, it is important to monitor the bioburden in the air and on surfaces in these labs. Establishing a comprehensive microbial monitoring program will help inform the monitoring and curation plans for Mars sample return which will include samples that are extremely biologically sensitive. In April of 2022 we began routinely collecting air samples in seven of the nine curation cleanrooms (Meteorite ISO 7 equivalent, Lunar ISO 6 equivalent, Stardust, Hayabusa2, OSIRIS-REx ISO 5 equivalent, and Genesis ISO 4 equivalent) using a sampling device that collects airborne biological particles on an electret filter instead conventional sampler that collect cells in a liquid media or onto organic rich Petri dishes. Electret is a generic term for electrostatically charged media. The charge on these materials increases particle trapping when compared to non-charged filters of similar thickness. N95 respirators also use electret filters. This dry sample collection method allows us to meet materials requirements for all the curation labs and reduces the risk of inadvertently introducing contamination as part of our monitoring effort. This method also allows us to preserve a portion of each sample for DNA extraction and next generation sequencing. DNA sequencing helps us to characterize the portion of the cleanroom microbiome that we cannot culture. We will present the results of our first 8 months of monitoring, compare these results to particle counts in the labs and to measurements made directly onto Petri dishes when possible. We will also make recommendations for modifications to the sampling method to improve sampling efficiency and preserve diversity.
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The astromaterials curation office at the NASA Johnson Space Center is responsible for curating and allocating all of the extraterrestrial samples collected by NASA. This includes lunar samples, meteorites, cometary material, asteroid samples and individual atoms of the solar wind. Some of these collections are susceptible to biological alteration by terrestrial microbes. I will describe the microbial monitoring of the clean rooms used to store these samples and the ecology we find therein. This research is helping NASA design better cleanrooms for even more sensitive samples like those currently being collected on Mars. I will also discuss our group’s research on improved identification methods, biological alteration of meteorites, and efforts to sample microbes on the outside of the International Space Station.
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