Examinando por Autor "Rettberg, P."

Mostrando 1 - 3 de 3

Acceso Abierto
Impact of Simulated Martian Conditions on (Facultatively) Anaerobic Bacterial Strains from Different Mars Analogue Sites.
(Multidisciplinary Digital Publishing Institute (MDPI), 2020-01-15) Beblo Vranesevic, K.; Bohmeier, M.; Schleumer, S.; Rabbow, E.; Perras, A. K.; Moissi Eichinger, C.; Schwendner, P.; Cockell, C. S.; Vannier, P.; Marteinsson, V. T.; Monaghan, E. P.; Riedo, A.; Ehrenfreund, P.; García Descalzo, L.; Gómez, F.; Malki, M.; Amils, R.; Gaboyer, F.; Hickman-Lewis, K.; Westall, F.; Cabezas, P.; Walter, N.; Rettberg, P.; Rettberg, P. [0000-0003-4439-2395]; García Descalzo, L. [0000-0002-0083-6786]; Cabezas, P. [0000-0002-6336-4093]; Marteinsson, V. [0000-0001-8340-821X]; Gómez, F. [0000-0001-9977-7060]
Five bacterial (facultatively) anaerobic strains, namely Buttiauxella sp. MASE-IM-9, Clostridium sp. MASE-IM-4, Halanaerobium sp. MASE-BB-1, Trichococcus sp. MASE-IM-5, and Yersinia intermedia MASE-LG-1 isolated from different extreme natural environments were subjected to Mars relevant environmental stress factors in the laboratory under controlled conditions. These stress factors encompassed low water activity, oxidizing compounds, and ionizing radiation. Stress tests were performed under permanently anoxic conditions. The survival rate after addition of sodium perchlorate (Na-perchlorate) was found to be species-specific. The inter-comparison of the five microorganisms revealed that Clostridium sp. MASE-IM-4 was the most sensitive strain (D-10-value (15 min, NaClO4) = 0.6 M). The most tolerant microorganism was Trichococcus sp. MASE-IM-5 with a calculated D-10-value (15 min, NaClO4) of 1.9 M. Cultivation in the presence of Na-perchlorate in Martian relevant concentrations up to 1 wt% led to the observation of chains of cells in all strains. Exposure to Na-perchlorate led to a lowering of the survival rate after desiccation. Consecutive exposure to desiccating conditions and ionizing radiation led to additive effects. Moreover, in a desiccated state, an enhanced radiation tolerance could be observed for the strains Clostridium sp. MASE-IM-4 and Trichococcus sp. MASE-IM-5. These data show that anaerobic micro-organisms from Mars analogue environments can resist a variety of Martian-simulated stresses either individually or in combination. However, responses were species-specific and some Mars-simulated extremes killed certain organisms. Thus, although Martian stresses would be expected to act differentially on microorganisms, none of the expected extremes tested here and found on Mars prevent the growth of anaerobic microorganisms.
Acceso Abierto
Implementing bioburden reduction and control on the deliquescent hydrogel of the HABIT/ExoMars 2022 instrument.
(Elsevier BV, 2020-04-21) Mathanlal, Thasshwin; Nazarious, Miracle Israel; Vakkada Ramachandran, A.; Zorzano, María Paz; Martín Torres, Javier; Rettberg, P.; Rettberg, P. [0000-0003-4439-2395]; Zorzano, M. P. [0000-0002-4492-9650]; Martín Torres, J. [0000-0001-6479-2236]; Vakkada Ramachandran, A. [0000-0003-0499-6370]; Unidad de Excelencia Científica María de Maeztu Centro de Astrobiología del Instituto Nacional de Técnica Aeroespacial y CSIC, MDM-2017-0737
The HabitAbility: Brines, Irradiation and Temperature (HABIT) instrument will be part of the ExoMars 2022 mission (ESA/Roscosmos) and will be the first European In-situ Resource Utilization (ISRU) instrument capable of producing liquid water on Mars. HABIT is composed by two modules: Environmental Package (EnvPack) and Brine Observation Transition To Liquid Experiment (BOTTLE). EnvPack will help to study the current habitability conditions on Mars investigating the air and surface thermal ranges and Ultraviolet (UV) irradiance; and BOTTLE is a container with four independent vessels housing deliquescent salts, which are known to be present on Mars, where the liquid water will be produced after deliquescence. In order to prevent capillarity of deliquescent or hydrated salts, a mixture of deliquescent salts with Super Absorbent Polymer (SAP) based on polyacrylamide is utilized. This mixture has deliquescent and hydrogel properties and can be reused by applying a thermal cycle, complying thus with the purpose of the instrument. A High Efficiency Particulate Air (HEPA) grade filter made of polytetrafluroethylene (PTFE) porous membrane sandwiched between spunbounded nonwoven fabric stands as a physical barrier allowing interaction between the gaseous molecules of the Martian atmosphere and the salt mixtures, and at the same time preventing the passage of any potential biological contamination from the cells to the outside or vice-versa. In addition to the physical barrier, a strict bioburden reduction and analysis procedure is applied to the hardware and the contained salt mixtures adhering to the European Cooperation for Space Standardization protocol of microbial examination of flight hardware (ECSS-Q-ST-70-55C). The deliquescent salts and the SAP products need to be properly treated independently to adhere to the planetary protection protocols. In this manuscript, we describe the bioburden reduction process utilized to sterilize the salt mixtures in BOTTLE and the assays adopted to validate the sterilization. We also describe the construction of a low-cost, portable ISO 7 cleanroom tent, exclusively designed for planetary protection tests. The sterilization process involves Dry Heat Microbial Reduction (DHMR) of the deliquescent salts and the SAP mixtures. The performance of SAP after DHMR is validated to ensure its working efficiency after sterilization. A slightly modified version of the standard swab assay is used in the validation process and a comparison is made between samples exposed to a thermal shock treatment and those without thermal shock, to determine the best assay to be applied for future space hardware utilizing such salt mixtures for planetary investigation and In-Situ Resource Utilization (ISRU). The demonstration of the compatibility of these products with the processes commonly required for space applications has implications for the future exploration of Mars.
Acceso Abierto
Taxonomic and functional analyses of intact microbial communities thriving in extreme, astrobiology-relevant, anoxic sites
(Spring Nature Research Journals, 2021-02-18) Kristin Bashir, A.; Wink, L.; Duller, S.; Schwendner, P.; Cockell, C.; Rettberg, P.; Mahnert, A.; Beblo Vranesevic, K.; Bohmeier, M.; Rabbow, E.; Gaboyer, F.; Westall, F.; Walter, N.; Cabezas, P.; García Descalzo, L.; Gómez, F.; Malki, M.; Amils, R.; Ehrenfreund, P.; Monaghan, E. P.; Vannier, P.; Marteinsson, V. T.; Erlacher, A.; Tanski, G.; Strauss, J.; Bashir, M.; Riedo, A.; Moissi Eichinger, C.; European Commission (EC); Swiss National Science Foundation (SNSF); Moissi Eichinger, C. [0000-0001-6755-6263]
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. 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. 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. 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.