Low-energy ion bombardment of frozen bacterial spores and its relevance to interplanetary space

Tuleta, M.; Gabla, L.; Szkarlat, A.

doi:10.1209/epl/i2004-10471-3

Cited by 9 publications

(6 citation statements)

References 39 publications

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“…The flux of ionizing radiation from the sun and galactic cosmic rays are three orders of magnitude higher on the Martian surface as compared to the surface of Earth due to the thin Martian atmosphere and the absence of a global magnetic field (Hassler et al, 2014 ). Nevertheless, ionizing radiation from the sun only poses a minor challenge for B. subtilis and D. radiodurans , and a cover that would protect against UV radiation would also shield from the charged particles in the solar wind (Tuleta et al, 2005 ; Paulino-Lima et al, 2011 ). Protection against galactic cosmic rays, mainly high-energy particles, requires much thicker shielding.…”

Section: Introductionmentioning

confidence: 99%

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

et al. 2017

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The habitability of Mars is determined by the physical and chemical environment. The effect of low water availability, temperature, low atmospheric pressure and strong UV radiation has been extensively studied in relation to the survival of microorganisms. In addition to these stress factors, it was recently found that silicates exposed to simulated saltation in a Mars-like atmosphere can lead to a production of reactive oxygen species. Here, we have investigated the stress effect induced by quartz and basalt abraded in Mars-like atmospheres by examining the survivability of the three microbial model organisms Pseudomonas putida, Bacillus subtilis, and Deinococcus radiodurans upon exposure to the abraded silicates. We found that abraded basalt that had not been in contact with oxygen after abrasion killed more than 99% of the vegetative cells while endospores were largely unaffected. Exposure of the basalt samples to oxygen after abrasion led to a significant reduction in the stress effect. Abraded quartz was generally less toxic than abraded basalt. We suggest that the stress effect of abraded silicates may be caused by a production of reactive oxygen species and enhanced by transition metal ions in the basalt leading to hydroxyl radicals through Fenton-like reactions. The low survivability of the usually highly resistant D. radiodurans indicates that the effect of abraded silicates, as is ubiquitous on the Martian surface, would limit the habitability of Mars as well as the risk of forward contamination. Furthermore, the reactivity of abraded silicates could have implications for future manned missions, although the lower effect of abraded silicates exposed to oxygen suggests that the effects would be reduced in human habitats.

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Section: Introductionmentioning

confidence: 99%

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

et al. 2017

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“…It is also a highly relevant parameter in the study of interplanetary transport of microbes either by natural impact processes (i.e., lithopanspermia) or as a consequence of human spaceflight activities (i.e., planetary protection) (reviewed in NASA, 2005;Nicholson, 2009;Nicholson et al, 2009;Horneck et al, 2010). In both cases, cosmic radiation constitutes the environmental space parameter that may limit microbial survival over long periods (Horneck, 1993;Koike and Oshima, 1993;Tuleta et al, 2005;Nicholson, 2009;Nicholson et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

Multifactorial Resistance ofBacillus subtilisSpores to High-Energy Proton Radiation: Role of Spore Structural Components and the Homologous Recombination and Non-Homologous End Joining DNA Repair Pathways

Moeller

Reitz

et al. 2012

Astrobiology

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The space environment contains high-energy charged particles (e.g., protons, neutrons, electrons, a-particles, heavy ions) emitted by the Sun and galactic sources or trapped in the radiation belts. Protons constitute the majority (87%) of high-energy charged particles. Spores of Bacillus species are one of the model systems used for astro-and radiobiological studies. In this study, spores of different Bacillus subtilis strains were used to study the effects of high energetic proton irradiation on spore survival. Spores of the wild-type B. subtilis strain [mutants deficient in the homologous recombination (HR) and non-homologous end joining (NHEJ) DNA repair pathways and mutants deficient in various spore structural components such as dipicolinic acid (DPA), a/b-type small, acidsoluble spore protein (SASP) formation, spore coats, pigmentation, or spore core water content] were irradiated as air-dried multilayers on spacecraft-qualified aluminum coupons with 218 MeV protons [with a linear energy transfer (LET) of 0.4 keV/lm] to various final doses up to 2500 Gy. Spores deficient in NHEJ-and HR-mediated DNA repair were significantly more sensitive to proton radiation than wild-type spores, indicating that both HR and NHEJ DNA repair pathways are needed for spore survival. Spores lacking DPA, a/b-type SASP, or with increased core water content were also significantly more sensitive to proton radiation, whereas the resistance of spores lacking pigmentation or spore coats was essentially identical to that of the wild-type spores. Our results indicate that a/b-type SASP, core water content, and DPA play an important role in spore resistance to high-energy proton irradiation, suggesting their essential function as radioprotectants of the spore interior.

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“…The major contribution to the mortality of spores is from exposure at low pressure during the first 30 min, before the freezing of the cellular content. Higher survival rates of the order of 90 % have been observed at 10 -6 Pa and 150 K and in all cases the water of spores is in icy phase (Tuleta et al, 2005). During the dehydration state the osmotic pressure of the cytoplasm is increasing, the freezing temperature is lowering and the icy state is inhibited.…”

Section: Spores At 10 -4 Pa and 10 Kmentioning

confidence: 95%

Interplanetary survival probability of Aspergillus terreus spores under simulated solar vacuum ultraviolet irradiation

Sarantopoulou¹,

Gomoiu²,

Kollia³

et al. 2011

Planetary and Space Science

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This work is a part of ESA/EU SURE project aiming to quantify the survival probability of fungal spores in space under solar irradiation in the vacuum ultraviolet (VUV) (110-180 nm) spectral region. The contribution and impact of VUV photons, vacuum, low temperature and their synergies, on the survival probability of Aspergillus terreus spores is measured at simulated space conditions on Earth. To simulate the solar VUV irradiation, the spores are irradiated with a continuous discharge VUV hydrogen photon source and a molecular fluorine laser, at low and high photon intensities at 10 15 photon m -2 s -1 and 3.9 x 10 27 photons pulse -1 m -2 s -1 respectively. The survival probability of spores is independent from the intensity and the fluence of photons, within certain limits, in agreement with previous studies. The spores are shielded from a thin carbon layer, which is formed quickly on the external surface of the proteinaceous membrane at higher photon intensities at the start of the VUV irradiation. Extrapolated the results in space conditions, for an interplanetary direct transfer orbit from Mars to Earth, the spores will be irradiated with 3.3 x 10 21 solar VUV photons m -2 . This photon fluence is equivalent to the irradiation of spores on Earth with 54 laser pulses with an experimental ~92% survival probability, disregarding the contribution of space vacuum and low temperature, or to continuous solar VUV irradiation for 38 days in space near the Earth with an extrapolated ~61% survival probability. The experimental results indicate that the damage of spores is mainly from the dehydration stress in vacuum. The high survival probability after 4 days in vacuum (~34 %), is due to the exudation of proteins on the external membrane, preventing thus further dehydration of spores. In addition, the survival probability is increasing to (~54%) at 10 K with 0.12 K/s cooling and heating rate.

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Low-energy ion bombardment of frozen bacterial spores and its relevance to interplanetary space

Cited by 9 publications

References 39 publications

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

Silicates Eroded under Simulated Martian Conditions Effectively Kill Bacteria—A Challenge for Life on Mars

Multifactorial Resistance ofBacillus subtilisSpores to High-Energy Proton Radiation: Role of Spore Structural Components and the Homologous Recombination and Non-Homologous End Joining DNA Repair Pathways

Interplanetary survival probability of Aspergillus terreus spores under simulated solar vacuum ultraviolet irradiation

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