Effect of microgravity & space radiation on microbes

Sustainable wastewater treatment and reuse in space

Exploring the vast extraterrestrial space is an inevitable trend with continuous human development. Water treatment and reuse are crucial in the limited and closed space that is available in spaceships or long-term use space bases that will be established in the foreseeable future. Dedicated water treatment technologies have experienced iterative development for more than 60 years since the first manned spaceflight was successfully launched. Herein, we briefly review the related wastewater characteristics and the history of water treatment in space stations, and we focus on future challenges and perspectives, aiming at providing insights for optimizing wastewater treatment technologies and closing the water cycle in future.

Development and implementation of a simulated microgravity setup for edible cyanobacteria

Regenerative life support systems for space crews recycle waste into water, food, and oxygen using different organisms. The European Space Agency's MELiSSA program uses the cyanobacterium Limnospira indica PCC8005 for air revitalization and food production. Before space use, components' compatibility with reduced gravity was tested. This study introduced a ground analog for microgravity experiments with oxygenic cyanobacteria under continuous illumination, using a random positioning machine (RPM) setup. L. indica PCC8005 grew slower under low-shear simulated microgravity, with proteome analysis revealing downregulation of ribosomal proteins, glutamine synthase, and nitrate uptake transporters, and upregulation of gas vesicle, photosystem I and II, and carboxysome proteins. Results suggested inhibition due to high oxygen partial pressure, causing carbon limitation when cultivated in low-shear simulated microgravity. A thicker stagnant fluid boundary layer reducing oxygen release in simulated microgravity was observed. These findings validate this RPM setup for testing the effects of non-terrestrial gravity on photosynthetic microorganisms.

Adaptation to space conditions of novel bacterial species isolated from the International Space Station revealed by functional gene annotations and comparative genome analysis

BACKGROUND

The extreme environment of the International Space Station (ISS) puts selective pressure on microorganisms unintentionally introduced during its 20+ years of service as a low-orbit science platform and human habitat. Such pressure leads to the development of new features not found in the Earth-bound relatives, which enable them to adapt to unfavorable conditions.

RESULTS

In this study, we generated the functional annotation of the genomes of five newly identified species of Gram-positive bacteria, four of which are non-spore-forming and one spore-forming, all isolated from the ISS. Using a deep-learning based tool-deepFRI-we were able to functionally annotate close to 100% of protein-coding genes in all studied species, overcoming other annotation tools. Our comparative genomic analysis highlights common characteristics across all five species and specific genetic traits that appear unique to these ISS microorganisms. Proteome analysis mirrored these genomic patterns, revealing similar traits. The collective annotations suggest adaptations to life in space, including the management of hypoosmotic stress related to microgravity via mechanosensitive channel proteins, increased DNA repair activity to counteract heightened radiation exposure, and the presence of mobile genetic elements enhancing metabolism. In addition, our findings suggest the evolution of certain genetic traits indicative of potential pathogenic capabilities, such as small molecule and peptide synthesis and ATP-dependent transporters. These traits, exclusive to the ISS microorganisms, further substantiate previous reports explaining why microbes exposed to space conditions demonstrate enhanced antibiotic resistance and pathogenicity.

CONCLUSION

Our findings indicate that the microorganisms isolated from ISS we studied have adapted to life in space. Evidence such as mechanosensitive channel proteins, increased DNA repair activity, as well as metallopeptidases and novel S-layer oxidoreductases suggest a convergent adaptation among these diverse microorganisms, potentially complementing one another within the context of the microbiome. The common genes that facilitate adaptation to the ISS environment may enable bioproduction of essential biomolecules need during future space missions, or serve as potential drug targets, if these microorganisms pose health risks. Video Abstract.

Flow structure of okra mucilage in rotating wall vessel system

The rotating-wall vessel (RWV) bioreactor, a 3D suspension culture system, faces challenges related to non-uniform tissue growth during the incubation of bone and heart tissues. Okra mucilage, an extract from okra pods with non-Newtonian rheological properties, has shown potential as a plasma replacement agent and has no induced cytotoxic effects. In this study, we investigated the flow structure of okra mucilage in rotating wall vessel system. By modifying the RWV and adding okra mucilage, we analyzed the flow structure using a high-speed camera and particle image velocimetry (PIV). Our results showed that okra mucilage creates a concentric circle-shaped rigid-like rotation at all rotation speeds (1-50 rpm). The high viscosity of okra mucilage resulted in a low terminal velocity for microparticles and quick response to rotational movements. These findings suggest that okra mucilage has the potential to enhance the uniformity of tissue growth in RWV systems by stabilizing the flow structure and reducing microparticle sedimentation.

Radiotolerance of N-cycle bacteria and their transcriptomic response to low-dose space-analogue ionizing irradiation

The advancement of regenerative life support systems (RLSS) is crucial to allow long-distance space travel. Within the Micro-Ecological Life Support System Alternative (MELiSSA), efficient nitrogen recovery from urine and other waste streams is vital to produce liquid fertilizer to feed food and oxygen production in subsequent photoautotrophic processes. This study explores the effects of ionizing radiation on nitrogen cycle bacteria that transform urea to nitrate. In particular, we assess the radiotolerance of Comamonas testosteroni, Nitrosomonas europaea, and Nitrobacter winogradskyi after exposure to acute γ-irradiation. Moreover, a comprehensive whole transcriptome analysis elucidates the effects of spaceflight-analogue low-dose ionizing radiation on the individual axenic strains and on their synthetic community o. This research sheds light on how the spaceflight environment could affect ureolysis and nitrification processes from a transcriptomic perspective.

Space aquatic chemistry: A roadmap for drinking water treatment in microgravity

Rapid advancement in aerospace technology has successfully enabled long-term life and economic activities in space, particularly in Low Earth Orbit (LEO), extending up to 2000 km from the mean sea level. However, the sustainance of the LEO Economy and its Environmental Control and Life Support System (ECLSS) still relies on a regular cargo supply of essential commodities (e.g., water, food) from Earth, for which there still is a lack of adequate and sustainable technologies. One key challenge in this context is developing water treatment technologies and standards that can perform effectively under microgravity conditions. Solving this technical challenge will be a milestone in providing a scientific basis and the necessary support mechanisms for establishing permanent bases in outer space and beyond. To identify clues towards solving this challenge, we looked back at relevant scientific research exploring novel technologies and standards for deep space exploration, also considering feedback for enhancing these technologies on land. Synthesizing our findings, we share our outlook for the future of drinking water treatment in microgravity. We also bring up a new concept for space aquatic chemistry, considering the closed environment of engineered systems operating in microgravity.

Whole transcriptome analysis highlights nutrient limitation of nitrogen cycle bacteria in simulated microgravity

Regenerative life support systems (RLSS) will play a vital role in achieving self-sufficiency during long-distance space travel. Urine conversion into a liquid nitrate-based fertilizer is a key process in most RLSS. This study describes the effects of simulated microgravity (SMG) on Comamonas testosteroni, Nitrosomonas europaea, Nitrobacter winogradskyi and a tripartite culture of the three, in the context of nitrogen recovery for the Micro-Ecological Life Support System Alternative (MELiSSA). Rotary cell culture systems (RCCS) and random positioning machines (RPM) were used as SMG analogues. The transcriptional responses of the cultures were elucidated. For CO2-producing C. testosteroni and the tripartite culture, a PermaLifeTM PL-70 cell culture bag mounted on an in-house 3D-printed holder was applied to eliminate air bubble formation during SMG cultivation. Gene expression changes indicated that the fluid dynamics in SMG caused nutrient and O2 limitation. Genes involved in urea hydrolysis and nitrification were minimally affected, while denitrification-related gene expression was increased. The findings highlight potential challenges for nitrogen recovery in space.

Combined effect of simulated microgravity and low-dose ionizing radiation on structure and antibiotic resistance of a synthetic community model of bacteria isolated from spacecraft assembly room

Understanding the structural and antibiotic resistance changes of microbial communities in space environments is critical for identifying potential pathogens that may pose health risks to astronauts and for preventing and controlling microbial contamination. The research to date on microbes under simulated space factors has primarily been carried out on single bacterial species under the individual effects of microgravity or low-dose radiation. However, microgravity (MG) and low-dose ionizing radiation (LDIR) coexist in the actual spacecraft environment, and microorganisms coexist as communities in the spacecraft environment. Thus, the microbial response to the real changes present during space habitation has not been adequately explored. To address this knowledge gap, we compared the dynamics of community composition and antibiotic resistance of synthetic bacterial communities under simulated microgravit, low-dose ionizing radiation, and the conditions combined, as it occurs in spacecraft. To ensure representative bacteria were selected, we co-cultured of 12 bacterial strains isolated from spacecraft cleanrooms. We found that the weakened competition between communities increased the possibility of species coexistence, community diversity, and homogeneity. The number of Bacilli increased significantly, while different species under the combined conditions showed various changes in abundance compared to those under the individual conditions. The resistance of the synthetic community to penicillins increased significantly under low doses of ionizing radiation but did not change significantly under simulated microgravity or the combined conditions. The results of functional predictions revealed that antibiotic biosynthesis and resistance increased dramatically in the community under space environmental stress, which confirmed the results of the drug sensitivity assays. Our results show that combined space environmental factors exert different effects on the microbial community structure and antibiotic resistance, which provides new insights into our understanding of the mechanisms of evolution of microorganisms in spacecraft, and is relevant to effective microbial pollution prevention and control strategies.

Microbial biomanufacturing for space-exploration-what to take and when to make

As renewed interest in human space-exploration intensifies, a coherent and modernized strategy for mission design and planning has become increasingly crucial. Biotechnology has emerged as a promising approach to increase resilience, flexibility, and efficiency of missions, by virtue of its ability to effectively utilize in situ resources and reclaim resources from waste streams. Here we outline four primary mission-classes on Moon and Mars that drive a staged and accretive biomanufacturing strategy. Each class requires a unique approach to integrate biomanufacturing into the existing mission-architecture and so faces unique challenges in technology development. These challenges stem directly from the resources available in a given mission-class-the degree to which feedstocks are derived from cargo and in situ resources-and the degree to which loop-closure is necessary. As mission duration and distance from Earth increase, the benefits of specialized, sustainable biomanufacturing processes also increase. Consequentially, we define specific design-scenarios and quantify the usefulness of in-space biomanufacturing, to guide techno-economics of space-missions. Especially materials emerged as a potentially pivotal target for biomanufacturing with large impact on up-mass cost. Subsequently, we outline the processes needed for development, testing, and deployment of requisite technologies. As space-related technology development often does, these advancements are likely to have profound implications for the creation of a resilient circular bioeconomy on Earth.

Experimentally Created Magnetic Force in Microbiological Space and On-Earth Studies: Perspectives and Restrictions

Magnetic force and gravity are two fundamental forces affecting all living organisms, including bacteria. On Earth, experimentally created magnetic force can be used to counterbalance gravity and place living organisms in conditions of magnetic levitation. Under conditions of microgravity, magnetic force becomes the only force that moves bacteria, providing an acceleration towards areas of the lowest magnetic field and locking cells in this area. In this review, we consider basic principles and experimental systems used to create a magnetic force strong enough to balance gravity. Further, we describe how magnetic levitation is applied in on-Earth microbiological studies. Next, we consider bacterial behavior under combined conditions of microgravity and magnetic force onboard a spacecraft. At last, we discuss restrictions on applications of magnetic force in microbiological studies and the impact of these restrictions on biotechnological applications under space and on-Earth conditions.

Modulation of the nanoscale motion rate of Candida albicans by X-rays

Introduction

Patients undergoing cancer treatment by radiation therapy commonly develop Candida albicans infections (candidiasis). Such infections are generally treated by antifungals that unfortunately also induce numerous secondary effects in the patient. Additional to the effect on the immune system, ionizing radiation influences the vital activity of C. albicans cells themselves; however, the reaction of C. albicans to ionizing radiation acting simultaneously with antifungals is much less well documented. In this study, we explored the effects of ionizing radiation and an antifungal drug and their combined effect on C. albicans.

Methods

The study essentially relied on a novel technique, referred to as optical nanomotion detection (ONMD) that monitors the viability and metabolic activity of the yeast cells in a label and attachment-free manner.

Results and discussion

Our findings demonstrate that after exposure to X-ray radiation alone or in combination with fluconazole, low-frequency nanoscale oscillations of whole cells are suppressed and the nanomotion rate depends on the phase of the cell cycle, absorbed dose, fluconazole concentration, and post-irradiation period. In a further development, the ONMD method can help in rapidly determining the sensitivity of C. albicans to antifungals and the individual concentration of antifungals in cancer patients undergoing radiation therapy.

Impact of simulated microgravity on bioremoval of heavy-metals by Lactobacillus acidophilus ATCC 4356 from water

There are several reports about the effect of gravity removal on some characteristics of microorganisms due to possible change in surface layer thickness and adherence properties. In this study, bioremoval efficiency of Lactobacillus acidophilus ATCC 4356 from water under simulated microgravity conditions was investigated. Furthermore, pretreatment effects (untreated, NaOH, and heat pretreated) of L. acidophilus ATCC 4356 on heavy metal removal was evaluated on microgravity, as our previous research showed impact of pretreatment on adherence properties of probiotics to environmental metals. The results showed that ability of L. acidophilus for arsenic adsorption enhanced following heat-pretreatment in simulated and normal gravity. Moreover, in both conditions of simulated microgravity and normal gravity NaOH-treated L. acidophilus increased the removal of cadmium and lead. In none of the conditions, pretreatment of lactobacillus affects mercury removal. Evaluation of stability of binding of L. acidophilus-heavy metal was investigated to check irreversibility of complex formation between microorganisms and metals in simulated gastrointestinal conditions. Data showed release of heavy metals from complex in normal gravity. Obtained results of this research show the favorable potential of simulated microgravity condition to increase bioremoval capacity of L. acidophilus for heavy metals.

Integrating bioinformatic strategies in spatial life science research

As space exploration programs progress, manned space missions will become more frequent and farther away from Earth, putting a greater emphasis on astronaut health. Through the collaborative efforts of researchers from various countries, the effect of the space environment factors on living systems is gradually being uncovered. Although a large number of interconnected research findings have been produced, their connection seems to be confused, and many unknown effects are left to be discovered. Simultaneously, several valuable data resources have emerged, accumulating data measuring biological effects in space that can be used to further investigate the unknown biological adaptations. In this review, the previous findings and their correlations are sorted out to facilitate the understanding of biological adaptations to space and the design of countermeasures. The biological effect measurement methods/data types are also organized to provide references for experimental design and data analysis. To aid deeper exploration of the data resources, we summarized common characteristics of the data generated from longitudinal experiments, outlined challenges or caveats in data analysis and provided corresponding solutions by recommending bioinformatics strategies and available models/tools.

Conjugation across Bacillus cereus and kin: A review

Horizontal gene transfer (HGT) is a major driving force in shaping bacterial communities. Key elements responsible for HGT are conjugation-like events and transmissible plasmids. Conjugative plasmids can promote their own transfer as well as that of co-resident plasmids. Bacillus cereus and relatives harbor a plethora of plasmids, including conjugative plasmids, which are at the heart of the group species differentiation and specification. Since the first report of a conjugation-like event between strains of B. cereus sensu lato (s.l.) 40 years ago, many have studied the potential of plasmid transfer across the group, especially for plasmids encoding major toxins. Over the years, more than 20 plasmids from B. cereus isolates have been reported as conjugative. However, with the increasing number of genomic data available, in silico analyses indicate that more plasmids from B. cereus s.l. genomes present self-transfer potential. B. cereus s.l. bacteria occupy diverse environmental niches, which were mimicked in laboratory conditions to study conjugation-related mechanisms. Laboratory mating conditions remain nonetheless simplistic compared to the complex interactions occurring in natural environments. Given the health, economic and ecological importance of strains of B. cereus s.l., it is of prime importance to consider the impact of conjugation within this bacterial group.

Unearthing terrestrial extreme microbiomes for searching terrestrial-like life in the Solar System

The possibility of life elsewhere in the universe has fascinated humankind for ages. To the best of our knowledge, life, as we know it, is limited to planet Earth; yet current investigation suggests that life might be more common than previously thought. In this review, we explore extreme terrestrial analogue environments in the search for some notable examples of extreme organisms, including overlooked microbial groups such as viruses, fungi, and protists, associated with limits of life on Earth. This knowledge is integral to provide the foundational principles needed to predict what sort of Earth-like organisms we might find in the Solar System and beyond, and to understand the future and origins of life on Earth.

Spaceflight Changes the Production and Bioactivity of Secondary Metabolites in Beauveria bassiana

Studies on microorganism response spaceflight date back to 1960. However, nothing conclusive is known concerning the effects of spaceflight on virulence and environmental tolerance of entomopathogenic fungi; thus, this area of research remains open to further exploration. In this study, the entomopathogenic fungus Beauveria bassiana (strain SB010) was exposed to spaceflight (ChangZheng 5 space shuttle during 5 May 2020 to 8 May 2020) as a part of the Key Research and Development Program of Guangdong Province, China, in collaboration with the China Space Program. The study revealed significant differences between the secondary metabolite profiles of the wild isolate (SB010) and the spaceflight-exposed isolate (BHT021, BH030, BHT098) of B. bassiana. Some of the secondary metabolites/toxins, including enniatin A2, brevianamide F, macrosporin, aphidicolin, and diacetoxyscirpenol, were only produced by the spaceflight-exposed isolate (BHT021, BHT030). The study revealed increased insecticidal activities for of crude protein extracts of B. bassiana spaceflight mutants (BHT021 and BH030, respectively) against Megalurothrips usitatus 5 days post application when compared crude protein extracts of the wild isolate (SB010). The data obtained support the idea of using space mutation as a tool for development/screening of fungal strains producing higher quantities of secondary metabolites, ultimately leading to increased toxicity/virulence against the target insect host.

Phenotypic and transcriptional changes in Escherichia coli K12 in response to simulated microgravity on the EagleStat, a new 2D microgravity analog for bacterial studies

Understanding the impacts of microgravity on bacteria is vital for successful long duration space missions. In this environment, bacteria have been shown to become more virulent, more resistant to antibiotics and to regulate biofilm formation. Since the study of these phenomena under true microgravity is cost- and time challenging, the use of ground-based analogs might allow researchers to test hypotheses before planning and executing experiments in the space environment. We designed and developed a 2D clinostat with capabilities robust enough for bacterial studies to allow for multiple simultaneous replicates of treatment and control conditions, thus permitting the generation of growth curves, in a single run. We used computational fluid dynamics (CFD), biofilm growth measurement and differential gene expression analysis on Escherichia coli cultures grown to late exponential phase (24 h) to validate the system's ability to simulate microgravity conditions. The CFD model with a rotational speed of 8 rpm projected cells growing homogeneously distributed along the tube, while the static condition showed the accumulation of the cells at the bottom of the container. These results were empirically validated with cultures on nutrient broth. Additionally, crystal violet assays showed that higher biofilm biomass grew on the internal walls of the gravity control tubes, compared to the simulated microgravity treatment. In contrast, when cells from both treatments were grown under standard conditions, those exposed to simulated microgravity formed significantly more biofilms than their gravity counterparts. Consistent with this result, transcriptome analysis showed the upregulation of several gene families related to biofilm formation and development such as cells adhesion, aggregation and regulation of cell motility, which provides a potential transcriptional explanation for the differential phenotype observed. Our results show that when operated under parameters for simulated microgravity, our 2D clinostat creates conditions that maintain a proportion of the cells in a constant free-falling state, consistent with the effect of microgravity. Also, the high-throughput nature of our instrument facilitates, significantly, bacterial experiments that require multiple sampling timepoints and small working volumes, making this new instrument extremely efficient.

Wound Healing Effects of Dracontomelon dao on Bacterial Infection Wounds in Rats and Its Potential Mechanisms under Simulated Space Environment

Dracontomelon dao (D. dao) is the leaves of Dracontomelon duperreanum Pierre (D. dao auct. non (Blanco) Merr. and Rolfe; D. sinense Stopf.). As a valuable traditional Chinese medicine from Anacardiaceae, D. dao has a long history of treating bedsores, skin ulcers, and other infection diseases. In addition, the volatile oil from D. dao leaves exhibits antitumor effects. However, these reported studies only focused on evaluating the antimicrobial efficacy on model strains in vitro, without paying attention to the antimicrobial activity and anti-inflammatory effects in vivo. This study was aimed to provide evidence of antimicrobial activity and anti-inflammatory and proangiogenesis activities of Dracontomelon dao (D. dao) on the skin of rats under simulated space environment. The weightlessness model of rats in space environment was established. Then, rats were given D. dao for 15 days. Wound healing effects of D. dao on histopathology and inflammatory cytokines in E. coli-induced wound infection in weightless rats were analyzed. Furthermore, the molecular biology technology was performed to evaluate the wound healing effects of D. dao on the relative protein level of NF-κB as well as PI3K/Akt signaling pathways. Immunohistochemistry was used for the protein expression of VEGFA. The wound healing effects of D. dao on bacterially infected wounds in rats were manifested by lowering the size of the wound and significantly increasing the shrinkage rate of the wound. D. dao had effect on alleviating histological damage of skin tissue and downregulation inflammatory cytokines level. In addition, the results indicated that D. dao has a regulatory effect on inflammation and angiogenesis and could regulate the relative protein level of MAPK/NF-κB as well as PI3K/AKT signaling pathways. The current study highlighted the crucial role of D. dao in relieving skin tissue injury in E. coli-induced wound infection in weightless rats by regulating the MAPK/NF-κB as well as PI3K/AKT signaling pathways. This study could provide a new agent for the treatment of bacterial infected wounds in simulated space environment.

Fungi are key players in extreme ecosystems

Extreme environments on Earth are typically devoid of macro life forms and are inhabited predominantly by highly adapted and specialized microorganisms. The discovery and persistence of these extremophiles provides tools to model how life arose on Earth and inform us on the limits of life. Fungi, in particular, are among the most extreme-tolerant organisms with highly versatile lifestyles and stunning ecological and morphological plasticity. Here, we overview the most notable examples of extremophilic and stress-tolerant fungi, highlighting their key roles in the functionality and balance of extreme ecosystems. The remarkable ability of fungi to tolerate and even thrive in the most extreme environments, which preclude most organisms, have reshaped current concepts regarding the limits of life on Earth.

The Impacts of Microgravity on Bacterial Metabolism

The inside of a space-faring vehicle provides a set of conditions unlike anything experienced by bacteria on Earth. The low-shear, diffusion-limited microenvironment with accompanying high levels of ionizing radiation create high stress in bacterial cells, and results in many physiological adaptations. This review gives an overview of the effect spaceflight in general, and real or simulated microgravity in particular, has on primary and secondary metabolism. Some broad trends in primary metabolic responses can be identified. These include increases in carbohydrate metabolism, changes in carbon substrate utilization range, and changes in amino acid metabolism that reflect increased oxidative stress. However, another important trend is that there is no universal bacterial response to microgravity, as different bacteria often have contradictory responses to the same stress. This is exemplified in many of the observed secondary metabolite responses where secondary metabolites may have increased, decreased, or unchanged production in microgravity. Different secondary metabolites in the same organism can even show drastically different production responses. Microgravity can also impact the production profile and localization of secondary metabolites. The inconsistency of bacterial responses to real or simulated microgravity underscores the importance of further research in this area to better understand how microbes can impact the people and systems aboard spacecraft.

Growth Behavior and Transcriptome Profile Analysis of Proteus mirabilis Strain Under Long- versus Short-Term Simulated Microgravity Environment

Spaceflight missions affect the behavior of microbes that are inevitably introduced into space environments and may impact astronauts’ health. Current studies have mainly focused on the biological characteristics and molecular mechanisms of microbes after short-term or long-term spaceflight, but few have compared the impact of various lengths of spaceflight missions on the characteristics of microbes. Researchers generally agree that microgravity (MG) is the most critical factor influencing microbial physiology in space capsules during flight missions. This study compared the growth behavior and transcriptome profile of Proteus mirabilis cells exposed to long-term simulated microgravity (SMG) with those exposed to short-term SMG. The results showed that long-term SMG decreased the growth rate, depressed biofilm formation ability, and affected several transcriptomic profiles, including stress response, membrane transportation, metal ion transportation, biological adhesion, carbohydrate metabolism, and lipid metabolism in contrast to short-term SMG. This study improved the understanding of long-term versus short-term SMG effects on P. mirabilis behavior and provided relevant references for analyzing the influence of P. mirabilis on astronaut health during spaceflights.

Multimode Representation of the Magnetic Field for the Analysis of the Nonlinear Behavior of Solar Activity as a Driver of Space Weather

Estimating and predicting space weather is important to the space industry and space missions. The driver of space weather, especially near the Earth, is solar activity, the study of which is an important task. In particular, there is a direction of problems based on models of solar magnetic field generation that require research. In our work, we build a nonlinear dynamic system of equations that describes the behavior of the solar magnetic field harmonics based on the alpha-omega dynamo model. We found that, at the beginning of the magnetic field generation process, when the dynamo number significantly exceeds the threshold, the most rapidly growing waves are in the lead. Then, over time, these waves stop growing quite quickly. In this case, the initially slowly increasing harmonics of the magnetic field become the leaders, which then make the main contribution to the process of magnetic field generation.

Aerospace Technology Improves Fermentation Potential of Microorganisms

It is highly possible to obtain high-quality microbial products in appreciable amounts, as aerospace technology is advancing continuously. Genome-wide genetic variations in microorganisms can be triggered by space microgravity and radiation. Mutation rate is high, mutant range is wide, and final mutant character is stable. Therefore, space microorganism breeding is growing to be a new and promising area in microbial science and has greatly propelled the development of fermentation technology. Numerous studies have discovered the following improvements of fermentation potential in microorganisms after exposure to space: (1) reduction in fermentation cycle and increase in growth rate; (2) improvement of mixed fermentation species; (3) increase in bacterial conjugation efficiency and motility; (4) improvement of the bioactivity of various key enzymes and product quality; (5) enhancement of multiple adverse stress resistance; (6) improvement of fermentation metabolites, flavor, appearance, and stability. Aerospace fermentation technology predominantly contributes to bioprocessing in a microgravity environment. Unlike terrestrial fermentation, aerospace fermentation keeps cells suspended in the fluid medium without significant shear forces. Space radiation and microgravity have physical, chemical, and biological effects on mutant microorganisms by causing alternation in fluid dynamics and genome, transcriptome, proteome, and metabolome levels.

Antimicrobial and Aging Properties of Ag-, Ag/Cu-, and Ag Cluster-Doped Amorphous Carbon Coatings Produced by Magnetron Sputtering for Space Applications

Inside a spacecraft, the temperature and humidity, suitable for the human crew onboard, also creates an ideal breeding environment for the proliferation of bacteria and fungi; this can present a hazard to human health and create issues for the safe running of equipment. To address this issue, wear-resistant antimicrobial thin films prepared by magnetron sputtering were developed, with the aim to coat key internal components within spacecrafts. Silver and copper are among the most studied active bactericidal materials, thus this work investigated the antibacterial properties of amorphous carbon coatings, doped with either silver, silver and copper, or with silver clusters. The longevity of these antimicrobial coatings, which is heavily influenced by metal diffusion within the coating, was also investigated. With a conventional approach, amorphous carbon coatings were prepared by cosputtering, to generate coatings that contained a range of silver and copper concentrations. In addition, coatings containing silver clusters were prepared using a separate cluster source to better control the metal particle size distribution in the amorphous carbon matrix. The particle size distributions were characterized by grazing-incidence small-angle X-ray scattering (GISAXS). Antibacterial tests were performed under both terrestrial gravity and microgravity conditions, to simulate the condition in space. Results show that although silver-doped coatings possess extremely high levels of antimicrobial activity, silver cluster-doped coatings are equally effective, while being more long-lived, despite containing a lower absolute silver concentration.

The smallest space miners: principles of space biomining

As we aim to expand human presence in space, we need to find viable approaches to achieve independence from terrestrial resources. Space biomining of the Moon, Mars and asteroids has been indicated as one of the promising approaches to achieve in-situ resource utilization by the main space agencies. Structural and expensive metals, essential mineral nutrients, water, oxygen and volatiles could be potentially extracted from extraterrestrial regolith and rocks using microbial-based biotechnologies. The use of bioleaching microorganisms could also be applied to space bioremediation, recycling of waste and to reinforce regenerative life support systems. However, the science around space biomining is still young. Relevant differences between terrestrial and extraterrestrial conditions exist, including the rock types and ores available for mining, and a direct application of established terrestrial biomining techniques may not be a possibility. It is, therefore, necessary to invest in terrestrial and space-based research of specific methods for space applications to learn the effects of space conditions on biomining and bioremediation, expand our knowledge on organotrophic and community-based bioleaching mechanisms, as well as on anaerobic biomining, and investigate the use of synthetic biology to overcome limitations posed by the space environments.

Biological and Mechanical Characterization of the Random Positioning Machine (RPM) for Microgravity Simulations

The rapid improvement of space technologies is leading to the continuous increase of space missions that will soon bring humans back to the Moon and, in the coming future, toward longer interplanetary missions such as the one to Mars. The idea of living in space is charming and fascinating; however, the space environment is a harsh place to host human life and exposes the crew to many physical challenges. The absence of gravity experienced in space affects many aspects of human biology and can be reproduced in vitro with the help of microgravity simulators. Simulated microgravity (s-μg) is applied in many fields of research, ranging from cell biology to physics, including cancer biology. In our study, we aimed to characterize, at the biological and mechanical level, a Random Positioning Machine in order to simulate microgravity in an in vitro model of Triple-Negative Breast Cancer (TNBC). We investigated the effects played by s-μg by analyzing the change of expression of some genes that drive proliferation, survival, cell death, cancer stemness, and metastasis in the human MDA-MB-231 cell line. Besides the mechanical verification of the RPM used in our studies, our biological findings highlighted the impact of s-μg and its putative involvement in cancer progression.

Development of Nitrogen Recycling Strategies for Bioregenerative Life Support Systems in Space

To enable long-distance space travel, the development of a highly efficient and robust system to recover nutrients from waste streams is imperative. The inability of the current physicochemical-based environmental control and life support system (ECLSS) on the ISS to produce food in situ and to recover water and oxygen at high enough efficiencies results in the need for frequent resupply missions from Earth. Therefore, alternative strategies like biologically-based technologies called bioregenerative life support systems (BLSSs) are in development. These systems aim to combine biological and physicochemical processes, which enable in situ water, oxygen, and food production (through the highly efficient recovery of minerals from waste streams). Hence, minimalizing the need for external consumables. One of the BLSS initiatives is the European Space Agency's (ESA) Micro-Ecological Life Support System Alternative (MELiSSA). It has been designed as a five-compartment bioengineered system able to produce fresh food and oxygen and to recycle water. As such, it could sustain the needs of a human crew for long-term space exploration missions. A prerequisite for the self-sufficient nature of MELiSSA is the highly efficient recovery of valuable minerals from waste streams. The produced nutrients can be used as a fertilizer for food production. In this review, we discuss the need to shift from the ECLSS to a BLSS, provide a summary of past and current BLSS programs and their unique approaches to nitrogen recovery and processing of urine waste streams. In addition, compartment III of the MELiSSA loop, which is responsible for nitrogen recovery, is reviewed in-depth. Finally, past, current, and future related ground and space demonstration and the space-related challenges for this technology are considered.

Advances in space microbiology

Microbial research in space is being conducted for almost 50 years now. The closed system of the International Space Station (ISS) has acted as a microbial observatory for the past 10 years, conducting research on adaptation and survivability of microorganisms exposed to space conditions. This adaptation can be either beneficial or detrimental to crew members and spacecraft. Therefore, it becomes crucial to identify the impact of two primary stress conditions, namely, radiation and microgravity, on microbial life aboard the ISS. Elucidating the mechanistic basis of microbial adaptation to space conditions aids in the development of countermeasures against their potentially detrimental effects and allows us to harness their biotechnologically important properties. Several microbial processes have been studied, either in spaceflight or using devices that can simulate space conditions. However, at present, research is limited to only a few microorganisms, and extensive research on biotechnologically important microorganisms is required to make long-term space missions self-sustainable.

Rad-Bio-App: a discovery environment for biologists to explore spaceflight-related radiation exposures

In addition to microgravity, spaceflight simultaneously exposes biology to a suite of other stimuli. For example, in space, organisms experience ionizing radiation environments that significantly differ in both quality and quantity from those normally experienced on Earth. However, data on radiation exposure during space missions is often complex to access and to understand, limiting progress towards defining how radiation affects organisms against the unique background of spaceflight. To help address this challenge, we have developed the Rad-Bio-App. This web-accessible database imports radiation metadata from experiments archived in NASA’s GeneLab data repository, and then allows the user to explore these experiments both in the context of their radiation exposure and through their other metadata and results. Rad-Bio-App provides an easy-to-use, graphically-driven environment to enable both radiation biologists and non-specialist researchers to visualize, and understand the impact of ionizing radiation on various biological systems in the context of spaceflight.

Stability of Antimicrobial Drug Molecules in Different Gravitational and Radiation Conditions in View of Applications during Outer Space Missions

The evolution of different antimicrobial drugs in terrestrial, microgravity and hypergravity conditions is presented within this review, in connection with their implementation during human space exploration. Drug stability is of utmost importance for applications in outer space. Instabilities may be radiation-induced or micro-/hypergravity produced. The antimicrobial agents used in space may have diminished effects not only due to the microgravity-induced weakened immune response of astronauts, but also due to the gravity and radiation-altered pathogens. In this context, the paper provides schemes and procedures to find reliable ways of fighting multiple drug resistance acquired by microorganisms. It shows that the role of multipurpose medicines modified at the molecular scale by optical methods in long-term space missions should be considered in more detail. Solutions to maintain drug stability, even in extreme environmental conditions, are also discussed, such as those that would be encountered during long-duration space exploratory missions. While the microgravity conditions may not be avoided in space, the suggested approaches deal with the radiation-induced modifications in humans, bacteria and medicines onboard, which may be fought by novel pharmaceutical formulation strategies along with radioprotective packaging and storage.

Microbial Pathogenicity in Space

After a less dynamic period, space exploration is now booming. There has been a sharp increase in the number of current missions and also of those being planned for the near future. Microorganisms will be an inevitable component of these missions, mostly because they hitchhike, either attached to space technology, like spaceships or spacesuits, to organic matter and even to us (human microbiome), or to other life forms we carry on our missions. Basically, we never travel alone. Therefore, we need to have a clear understanding of how dangerous our "travel buddies" can be; given that, during space missions, our access to medical assistance and medical drugs will be very limited. Do we explore space together with pathogenic microorganisms? Do our hitchhikers adapt to the space conditions, as well as we do? Do they become pathogenic during that adaptation process? The current review intends to better clarify these questions in order to facilitate future activities in space. More technological advances are needed to guarantee the success of all missions and assure the reduction of any possible health and environmental risks for the astronauts and for the locations being explored.

Effects of Simulated Microgravity on the Proteome and Secretome of the Polyextremotolerant Black Fungus Knufia chersonesos

Black fungi are a group of melanotic microfungi characterized by remarkable polyextremotolerance. Due to a broad ecological plasticity and adaptations at the cellular level, it is predicted that they may survive in a variety of extreme environments, including harsh niches on Earth and Mars, and in outer space. However, the molecular mechanisms aiding survival, especially in space, are yet to be fully elucidated. Based on these premises, the rock-inhabiting black fungus Knufia chersonesos (Wt) and its non-melanized mutant (Mut) were exposed to simulated microgravity-one of the prevalent features characterizing space conditions-by growing the cultures in high-aspect-ratio vessels (HARVs). Qualitative and quantitative proteomic analyses were performed on the mycelia and supernatant of culture medium (secretome) to assess alterations in cell physiology in response to low-shear simulated microgravity (LSSMG) and to ultimately evaluate the role of cell-wall melanization in stress survival. Differential expression was observed for proteins involved in carbohydrate and lipid metabolic processes, transport, and ribosome biogenesis and translation via ribosomal translational machinery. However, no evidence of significant activation of stress components or starvation response was detected, except for the scytalone dehydratase, enzyme involved in the synthesis of dihydroxynaphthalene (DNH) melanin, which was found to be upregulated in the secretome of the wild type and downregulated in the mutant. Differences in protein modulation were observed between K. chersonesos Wt and Mut, with several proteins being downregulated under LSSMG in the Mut when compared to the Wt. Lastly, no major morphological alterations were observed following exposure to LSSMG. Similarly, the strains' survivability was not negatively affected. This study is the first to characterize the response to simulated microgravity in black fungi, which might have implications on future astrobiological missions.

Decreased Biofilm Formation Ability of a Multidrug-Resistant Pseudomonas aeruginosa Strain After Exposure to a Simulated Microgravity Environment

Background: The refractory infection induced by multidrug-resistant (MDR) Pseudomonas aeruginosa has become one of the most urgent problems in hospitals. The biofilms formed by P. aeruginosa increase its resistance to antibiotics. A simulated microgravity (SMG) environment provides a platform to understand the factors affecting biofilm formation in bacteria. Objectives: This study aimed to investigate the SMG effects on MDR P. aeruginosa biofilm formation and explore the relevant mechanisms. Methods: In this study, a clinostat was used to simulate a microgravity (MG) environment. The motility and biofilm formation ability of MDR P. aeruginosa were observed using the swimming test and the crystal violet staining method, respectively. The underlying mechanism of phenotypic changes was further investigated by comparative transcriptomic analysis. Results: Multidrug-resistant P. aeruginosa grown under the SMG condition exhibited decreased swimming motility and biofilm formation ability compared to those under the normal gravity (NG) condition. Further analysis revealed that the decreased swimming motility and biofilm formation ability could be attributed to the downregulated expression of genes responsible for flagellar synthesis (flhB, fliQ, and fliR) and type IV pili biogenesis (pilDEXY1Y2VW). Conclusions: This is the first study to perform experiments on MDR P. aeruginosa under the SMG condition. It will be beneficial to understand the mechanism of MDR P. aeruginosa biofilm formation and develop new treatment strategies for infectious diseases induced by MDR P. aeruginosa in the future.

Exploration of space to achieve scientific breakthroughs

Living organisms adapt to changing environments using their amazing flexibility to remodel themselves by a process called evolution. Environmental stress causes selective pressure and is associated with genetic and phenotypic shifts for better modifications, maintenance, and functioning of organismal systems. The natural evolution process can be used in complement to rational strain engineering for the development of desired traits or phenotypes as well as for the production of novel biomaterials through the imposition of one or more selective pressures. Space provides a unique environment of stressors (e.g., weightlessness and high radiation) that organisms have never experienced on Earth. Cells in the outer space reorganize and develop or activate a range of molecular responses that lead to changes in cellular properties. Exposure of cells to the outer space will lead to the development of novel variants more efficiently than on Earth. For instance, natural crop varieties can be generated with higher nutrition value, yield, and improved features, such as resistance against high and low temperatures, salt stress, and microbial and pest attacks. The review summarizes the literature on the parameters of outer space that affect the growth and behavior of cells and organisms as well as complex colloidal systems. We illustrate an understanding of gravity-related basic biological mechanisms and enlighten the possibility to explore the outer space environment for application-oriented aspects. This will stimulate biological research in the pursuit of innovative approaches for the future of agriculture and health on Earth.

Growth of Lactobacillus reuteri DSM17938 Under Two Simulated Microgravity Systems: Changes in Reuterin Production, Gastrointestinal Passage Resistance, and Stress Genes Expression Response

Extreme factors such as space microgravity, radiation, and magnetic field differ from those that occur on Earth. Microgravity may induce and select some microorganisms for physiological, metabolic, and/or genetic variations. This study was conducted to determine the effects of simulated microgravity conditions on the metabolism and gene expression of the probiotic bacterium Lactobacillus reuteri DSM17938. To investigate microbial response to simulated microgravity, two devices-the rotating wall vessel (RWV) and the random positioning machine (RPM)-were used. Microbial growth, reuterin production, and resistance to gastrointestinal passage were assessed, and morphological characteristics were analyzed by scanning electron microscopy. The expression of some selected genes that are responsive to stress conditions and to bile salts stress was evaluated through real-time quantitative polymerase chain reaction assay. Monitoring of bacterial growth, cell size, and shape under simulated microgravity did not reveal differences compared with 1 × g controls. On the contrary, an enhanced production of reuterin and a greater tolerance to the gastrointestinal passage were observed. Moreover, some stress genes were upregulated under RWV conditions, especially after 24 h of treatment, whereas RPM conditions seemed to determine a downregulation over time of the same stress genes. These results show that simulated microgravity could alter some physiological characteristics of L. reuteri DSM17938 with regard to tolerance toward stress conditions encountered on space missions and could be useful to elucidate the adaptation mechanisms of microbes to the space environment.

Introducing Vibrio natriegens as a Microbial Model Organism for Microgravity Research

Microbial contamination of human-tended spacecraft is unavoidable, making the study of microbial growth under space conditions essential for the preservation of astronauts' health and equipment integrity. Previous studies suggested that spaceflight conditions, such as microgravity, cause a range of physiological microbial alterations including increased growth yields and decreased antibiotic susceptibility. Because of its fast generation time, Vibrio natriegens could be used as a model organism for a variety of studies where generation time is a critical factor. In this study, V. natriegens was used as a tool to study growth characteristics by determining the viable cell number and antibiotic susceptibility under simulated microgravity using a 2-D clinostat (60 rpm) to establish a test system that resolves changes in microbial growth on a solid surface (agar) under microgravity. The data show that V. natriegens biomass increases significantly after 24 h at 37°C under simulated microgravity. The final cell population after cultivation under simulated microgravity was 60-fold greater than when cultivated under normal terrestrial gravity (1 × g). No change in susceptibility to the antibiotic rifampicin after cultivation under simulated microgravity or normal gravity was detected. These data show that V. natriegens is a new and innovative model organism for microbial microgravity research.

Increased growth rate and amikacin resistance of Salmonella enteritidis after one-month spaceflight on China's Shenzhou-11 spacecraft

China launched the Tiangong-2 space laboratory in 2016 and will eventually build a basic space station by the early 2020s. These spaceflight missions require astronauts to stay on the space station for more than 6 months, and they inevitably carry microbes into the space environment. It is known that the space environment affects microbial behavior, including growth rate, biofilm formation, virulence, drug resistance, and metabolism. However, the mechanisms of these alternations have not been fully elucidated. Therefore, it is beneficial to monitor microorganisms for preventing infections among astronauts in a space environment. Salmonella enteritidis is a Gram-negative bacterial pathogen that commonly causes acute gastroenteritis in humans. In this study, to better understand the effects of the space environment on S. enteritidis, a S. enteritidis strain was taken into space by the Shenzhou-11 spacecraft from 17 October 2016 to 18 November 2016, and a ground simulation with similar temperature conditions was simultaneously performed as a control. It was found that the flight strain displayed an increased growth rate, enhanced amikacin resistance, and some metabolism alterations compared with the ground strain. Enrichment analysis of proteome revealed that the increased growth rate might be associated with differentially expressed proteins involved in transmembrane transport and energy production and conversion assembly. A combined transcriptome and proteome analysis showed that the amikacin resistance was due to the downregulation of the oppA gene and oligopeptide transporter protein OppA. In conclusion, this study is the first systematic analysis of the phenotypic, genomic, transcriptomic, and proteomic variations in S. enteritidis during spaceflight and will provide beneficial insights for future studies on space microbiology.