Extreme Ionizing-Radiation-Resistant Bacterium

There is a growing concern that desiccation and extreme radiation-resistant, non-spore-forming microorganisms associated with spacecraft surfaces can withstand space environmental conditions and subsequent proliferation on another solar body. Such forward contamination would jeopardize future life detection or sample return technologies. The prime focus of NASA s planetary protection efforts is the development of strategies for inactivating resistance-bearing microorganisms. Eradification techniques can be designed to target resistance-conferring microbial populations by first identifying and understanding their physiologic and biochemical capabilities that confers its elevated tolerance (as is being studied in Deinococcus phoenicis, as a result of this description). Furthermore, hospitals, food, and government agencies frequently use biological indicators to ensure the efficacy of a wide range of radiation- based sterilization processes. Due to their resistance to a variety of perturbations, the non-spore forming D. phoenicis may be a more appropriate biological indicator than those currently in use. The high flux of cosmic rays during space travel and onto the unshielded surface of Mars poses a significant hazard to the survival of microbial life. Thus, radiation-resistant microorganisms are of particular concern that can survive extreme radiation, desiccation, and low temperatures experienced during space travel. Spore-forming bacteria, a common inhabitant of spacecraft assembly facilities, are known to tolerate these extreme conditions. Since the Viking era, spores have been utilized to assess the degree and level of microbiological contamination on spacecraft and their associated spacecraft assembly facilities. Members of the non-spore-forming bacterial community such as Deinococcus radiodurans can survive acute exposures to ionizing radiation (5 kGy), ultraviolet light (1 kJ/sq m), and desiccation (years). These resistive phenotypes of Deinococcus enhance the potential for transfer, and subsequent proliferation, on another solar body such as Mars and Europa. These organisms are more likely to escape planetary protection assays, which only take into account presence of spores. Hence, presences of extreme radiation-resistant Deinococcus in the cleanroom facility where spacecraft are assembled pose a serious risk for integrity of life-detection missions. The microorganism described herein was isolated from the surfaces of the cleanroom facility in which the Phoenix Lander was assembled. The isolated bacterial strain was subjected to a comprehensive polyphasic analysis to characterize its taxonomic position. This bacterium exhibits very low 16SrRNA similarity with any other environmental isolate reported to date. Both phenotypic and phylogenetic analyses clearly indicate that this isolate belongs to the genus Deinococcus and represents a novel species. The name Deinococcus phoenicis was proposed after the Phoenix spacecraft, which was undergoing assembly, testing, and launch operations in the spacecraft assembly facility at the time of isolation. D. phoenicis cells exhibited higher resistance to ionizing radiation (cobalt-60; 14 kGy) than the cells of the D. radiodurans (5 kGy). Thus, it is in the best interest of NASA to thoroughly characterize this organism, which will further assess in determining the potential for forward contamination. Upon the completion of genetic and physiological characteristics of D. phoenicis, it will be added to a planetary protection database to be able to further model and predict the probability of forward contamination

Hardy Bacterium Isolated From Two Geographically Distinct Spacecraft Assembly Cleanroom Facilities

Earlier studies have confirmed that a tenacious hardy bacterial population manages to persist and survive throughout a spacecraft assembly process. The widespread detection of these organisms underscores the challenges in eliminating them completely. Only comprehensive and repetitive microbial diversity studies of geographically distinct cleanroom facilities will bolster the understanding of planetary protection relevant microbes. Extensive characterizations of the physiological traits demonstrated by cleanroom microbes will aid NASA in gauging the forward contamination risk that hardy bacteria (such as Tersicoccus phoenicis) pose to spacecraft. This study reports on the isolation and identification of two gram-positive, non-motile, non-spore-forming bacterial strains from the spacecraft assembly facilities at Kennedy Space Center, Florida, USA and Centre Spatial Guyanais, Kourou, French Guiana. DNA-DNA relatedness values between the novel strains indicates that these novel strains were indeed members of a same species. Phylogenetic evidence derived from a 16S ribosomal DNA analysis indicated that both the novel strains are less closely related to all other Arthrobacter species

Detecting biochemical evidence for life with the signs of life detector (solid) in an anaerobic microorganism under fossilization conditions

The definitive detection of biosignatures in the context of astrobiological missions to Mars is not without difficulty. Could it be possible to detect biomarkers from an extinct form of life in a very ancient material? The traces of some microorganisms can be well preserved thanks to rapid mineralization of the organisms and cementation of the sediments in which they occur [1]. Thus biosignatures could be indicators of either extant or extinct life, the search for which is one of the main objectives of Mars exploration [1]. The central motivation of the MASE project (Mars Analogues for Space Exploration) is to gain knowledge about the habitability of Mars by the study of the adaptation of anaerobic life forms to extreme environments, their environmental context, and the methods used to detect their biosignatures. Within this background a fundamental target of MASE project is to improve and optimize methods for biosignature detection in samples with low biomass from certain Mars analogue sites. In this context we applied antibody multiarray competitive immunoassay to follow the evolution of specific biochemical signatures from a culture under fossilization conditions. An antibody multiarray competitive immunoassay for the simultaneous detection of compounds of a wide range of molecular sizes or whole spores and cells [2] [3] has revealed as suitable option to achieve this MASE purpose. It consists in a rapid strategy to detect a huge set of different epitopes in extracted samples by a sandwich multiarray immunoassay in a slide or LDChip (Life Detector Chip) where huge range of different antibodies are coated. In this report, we present the results from an experiment in which we followed the biochemical signatures from a growing culture of an isolate of Yersinia sp. in fresh media and in a culture growing under fossilization conditions in silica and gypsum. A decrease in the signal of relative fluorescence of antibody-antigen binding (biomarkers detected) is observed when comparing an untreated Yersinia sp. culture and those induced to mineralization at different time points

The UK Centre for Astrobiology:A Virtual Astrobiology Centre. Accomplishments and Lessons Learned, 2011-2016

Authors thank all those individuals, UK research councils, funding agencies, nonprofit organisations, companies and corporations and UK and non-UK government agencies, who have so generously supported our aspirations and hopes over the last 5 years and supported UKCA projects. They include the STFC, the Engineering and Physical Sciences Research Council (EPSRC), the Natural Environmental Research Council (NERC), the EU, the UK Space Agency, NASA, the European Space Agency (ESA), The Crown Estate, Cleveland Potash and others. The Astrobiology Academy has been supported by the UK Space Agency (UKSA), National Space Centre, the Science and Technology Facilities Council (STFC), Dynamic Earth, The Royal Astronomical Society, The Rotary Club (Shetlands) and the NASA Astrobiology Institute.The UK Centre for Astrobiology (UKCA) was set up in 2011 as a virtual center to contribute to astrobiology research, education, and outreach. After 5 years, we describe this center and its work in each of these areas. Its research has focused on studying life in extreme environments, the limits of life on Earth, and implications for habitability elsewhere. Among its research infrastructure projects, UKCA has assembled an underground astrobiology laboratory that has hosted a deep subsurface planetary analog program, and it has developed new flow-through systems to study extraterrestrial aqueous environments. UKCA has used this research backdrop to develop education programs in astrobiology, including a massive open online course in astrobiology that has attracted over 120,000 students, a teacher training program, and an initiative to take astrobiology into prisons. In this paper, we review these activities and others with a particular focus on providing lessons to others who may consider setting up an astrobiology center, institute, or science facility. We discuss experience in integrating astrobiology research into teaching and education activities.Publisher PDFPeer reviewe

A Low-Diversity Microbiota Inhabits Extreme Terrestrial Basaltic Terrains and Their Fumaroles : Implications for the Exploration of Mars

A major objective in the exploration of Mars is to test the hypothesis that the planet hosted life. Even in the absence of life, the mapping of habitable and uninhabitable environments is an essential task in developing a complete understanding of the geological and aqueous history of Mars and, as a consequence, understanding what factors caused Earth to take a different trajectory of biological potential. We carried out the aseptic collection of samples and comparison of the bacterial and archaeal communities associated with basaltic fumaroles and rocks of varying weathering states in Hawai'i to test four hypotheses concerning the diversity of life in these environments. Using high-throughput sequencing, we found that all these materials are inhabited by a low-diversity biota. Multivariate analyses of bacterial community data showed a clear separation between sites that have active fumaroles and other sites that comprised relict fumaroles, unaltered, and syn-emplacement basalts. Contrary to our hypothesis that high water flow environments, such as fumaroles with active mineral leaching, would be sites of high biological diversity, alpha diversity was lower in active fumaroles compared to relict or nonfumarolic sites, potentially due to high-temperature constraints on microbial diversity in fumarolic sites. A comparison of these data with communities inhabiting unaltered and weathered basaltic rocks in Idaho suggests that bacterial taxon composition of basaltic materials varies between sites, although the archaeal communities were similar in Hawai'i and Idaho. The taxa present in both sites suggest that most of them obtain organic carbon compounds from the atmosphere and from phototrophs and that some of them, including archaeal taxa, cycle fixed nitrogen. The low diversity shows that, on Earth, extreme basaltic terrains are environments on the edge of sustaining life with implications for the biological potential of similar environments on Mars and their exploration by robots and humans.Peer reviewe

MEXEM – Mars Exposed Extremophile Mixture – a space experiment to investigate the capability of anaerobic organisms to survive on Mars

Assessing the habitability of Mars and detecting life, if it ever existed there, depends on knowledge of whether the combined environmental stresses experienced on Mars are compatible with life as we know it and whether a record of that life could ever be detected. So far, only few investigations were performed to understand the combined effect of different environmental stresses on survival and growth of anaerobic and extremophilic organisms. In the space experiment MEXEM (formerly known as MASE-in-SPACE) the hypothesis will be tested that selected terrestrial organisms, enrichment cultures and original samples from extreme Mars-analogue environments on Earth are able to withstand the Martian environ- mental stress factors due to their highly effective cellular and molecular adaptation and repair mechanisms. In addition, artificially fossilized and aged isolates from Mars-analogue environments on Earth will be examined and assessed with respect to their suitability for biosigna- ture identification. MEXEM samples will be (i) oxygen-depleted natural sediment samples, (ii) natural sediments spiked with selected, defined strains representative for the respective analogue site, (iii) individual (facultative) anaerobic / micro-aerophilic species including ciliates and viruses, (iv) defined mixtures of these biological entities, (v) isolated strains from samples collected inside the ISS and (vi) artificially fossilized isolates from the natural environments. Most of these samples and isolates were obtained from Mars-analogue envi- ronments on Earth in the frame of the EC funded project MASE (Grant Agreement 607297) and from the space experiment EXTREMOPHILES (PI C. Moissl-Eichinger). MEXEM will be flown outside on the ISS in the new exobiology facility ESA is building now. It offers the possibility to simulate of the martian environment, in particular the martian UV cl e, which cannot be done in the lab, but also martian atmosphere and pressure in LEO

MICROORGANISMS FROM MARS ANALOGUE ENVIRONMENTS IN EARTH - COULD THEY SURVIVE ON MARS?

Assessing the habitability of Mars and detecting life, if it was ever there, depends on knowledge of whether the combined environmental stresses experienced on Mars are compatible with life and whether a record of that life could ever be detected. Many combinations of Mars relevant stress factors, such as high radiation dose rates and high UV uences combined with high salt concentrations, and low water activity, have not been investigated. In particular, the response of anaerobic organisms to Mars-like stress factors and combinations thereof are not known. In the EC project MASE (Mars Analogues for Space Exploration) we address these limitations by characterising different Mars analogue environments on Earth, isolating microorganisms from these sites and exposing them to Mars relevant stress factors alone and in combination. We want to find out, if these bacteria respond in an additive or synergistic way and if they would be able to survive on Mars. So far, eight only distantly related microorganisms are under detailed investigation, e.g Yersinia sp., Halanaerobium sp., Acidiphilum sp. Desulfovibrio sp.. Unexpectedly, a Yersinia strain turned out to be quite resistant, especially against desicca- tion and oxidising compounds, whereas a Desulfovibrio sp. strain exhibit a relatively high radiation resistance. The future experiments aim at the identification of the underlying cellu- lar and molecular mechanisms and the comparison to other new isolates from Mars analogue environments on Earth in the MASE project

Taxonomic and functional analyses of intact microbial communities thriving in extreme, astrobiology-relevant, anoxic sites

Background: Extreme terrestrial, analogue environments are widely used models to study the limits of life and to infer habitability of extraterrestrial settings. In contrast to Earth’s ecosystems, potential extraterrestrial biotopes are usually characterized by a lack of oxygen. Methods: In the MASE project (Mars Analogues for Space Exploration), we selected representative anoxic analogue environments (permafrost, salt-mine, acidic lake and river, sulfur springs) for the comprehensive analysis of their microbial communities. We assessed the microbiome profile of intact cells by propidium monoazide-based amplicon and shotgun metagenome sequencing, supplemented with an extensive cultivation effort. Results: The information retrieved from microbiome analyses on the intact microbial community thriving in the MASE sites, together with the isolation of 31 model microorganisms and successful binning of 15 high-quality genomes allowed us to observe principle pathways, which pinpoint specific microbial functions in the MASE sites compared to moderate environments. The microorganisms were characterized by an impressive machinery to withstand physical and chemical pressures. All levels of our analyses revealed the strong and omnipresent dependency of the microbial communities on complex organic matter. Moreover, we identified an extremotolerant cosmopolitan group of 34 poly-extremophiles thriving in all sites. Conclusions: Our results reveal the presence of a core microbiome and microbial taxonomic similarities between saline and acidic anoxic environments. Our work further emphasizes the importance of the environmental, terrestrial parameters for the functionality of a microbial community, but also reveals a high proportion of living microorganisms in extreme environments with a high adaptation potential within habitability borders

Mars Analogues for space exploration - from anaerobic field site to culture collection

Astrobiology seeks to understand the limits of life and to determine the physiology of organisms in order to be able to better assess the potential habitability of other worlds and improve our ability to assay them for the presence of life. To successfully achieve this we require representative microorganisms from environments on Earth that in physical and/or chemical conditions approximate to extraterrestrial environments. The most challenging of these environments with respect to the sample collection and follow on isolation and cultivation of microorganisms are anaerobic environments. Here we describe a systematic approach to this challenge and aim to provide a guideline for future fieldwork and sampling campaigns. We selected a number of anaerobic environments based on characteristics that make them analogous to past and present locations on Mars (Icelandic lakes, sulfidic springs, deep hypersaline environments, acidic iron-rich environments, and permafrost). We implemented a culturing approach to enrich organisms from these environments under anaerobic conditions using a defined medium that would allow for all organisms to be grown under identical culturing conditions m future physiological comparisons. We then isolated anaerobic microorganisms, carried out a study of their basic physiology and deposited these organisms in the DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH) culture collection to make them available to astrobiologists and microbiologists. This project represents the first attempt to implement a coordinated effort from the selection of extraterrestrial analog sites through to the isolation and the characterisation of organisms and their deposition within a culture collection