Microorganisms able to tolerate environmental extremes, or extremophiles, are ideal candidates to extend our knowledge on the limitations for terrestrial life, including sporicidal treatments, and on their ability to survive under conditions mimicking space environments. The spore resistance of bacilli isolated from extreme environments, cold (Antarctic soils) and hot (shallow hydrothermal vents of Eolian Islands, Italy), was evaluated towards environmental stressors (wet- and dry-heat, low and high pH values), sporicidal treatments and stresses simulating space-environments (UV-C and X-rays irradiations, desiccations by low pressure, exposition to oxidizing agents and low pressure plasma), as those from the planet surface of Europa (the satellite of Jupiter), Enceladus (the satellite of Saturn) and Mars. Spores from two thermophilic Eolian strains, Bacillus horneckiae SBP3 (SBP3) and B. licheniformis T14, and a psychrophilic Antarctic strain, B. simplex A43, were frequently the most resistant against simulating space conditions as UV-C, X-ray and heavy ions radiation. Despite belonging to the same species, spores from strains Bacillus horneckiae SBP3 and Bacillus horneckiae DSM 23175T responded differently to stresses, which may reflect the adaptation to harsh environmental conditions of the Eolian thermophilic strain. Additional comparisons were made with reference strains used in Astrobiology studies, isolated from spacecraft assembly facilities (B. horneckiae, B. nealsonii and B. pumilus SAFR032), and the biodosimetry strain and space microbiology model organisms B. subtilis 168. Spores of B. horneckiae SBP3 were able to survive stressing conditions (exposition to heat, acid and alkaline stresses, UV-C, X-rays, heavy ions, low pressure plasma, desiccation and hydrogen peroxide), often at higher degree than those of B. subtilis. The results obtained by Raman spectroscopy showed that the damages induced by heat stress to spores are related to the denaturation of proteins, rather than to those of nucleic acids. This finding suggests, that the mechanisms involved to contrast the heat stress are probably related to the thermostability of small-acid soluble proteins in spore-core. The resistance of spores to terrestrial environmental stressors could also be determinant in resisting to space stressors (as UV-C and X-rays radiations, exposure at temperature 95 and 130°C and desiccation stress). Moreover, exopolysaccharides structure and composition, involved in the biofilm formation, could be also considered as a mechanism to protect spores under stress conditions. As bacterial multi-resistant forms, the studied spores are expected to possess novel, unexplored applicative potentials in different contexts, such as new bio-indicators for safety and security in human activities, as well as in Astrobiology, in space exploration missions and “Planetary Protection” programs.

Microorganisms able to tolerate environmental extremes, or extremophiles, are ideal candidates to extend our knowledge on the limitations for terrestrial life, including sporicidal treatments, and on their ability to survive under conditions mimicking space environments. The spore resistance of bacilli isolated from extreme environments, cold (Antarctic soils) and hot (shallow hydrothermal vents of Eolian Islands, Italy), was evaluated towards environmental stressors (wet- and dry-heat, low and high pH values), sporicidal treatments and stresses simulating space-environments (UV-C and X-rays irradiations, desiccations by low pressure, exposition to oxidizing agents and low pressure plasma), as those from the planet surface of Europa (the satellite of Jupiter), Enceladus (the satellite of Saturn) and Mars. Spores from two thermophilic Eolian strains, Bacillus horneckiae SBP3 (SBP3) and B. licheniformis T14, and a psychrophilic Antarctic strain, B. simplex A43, were frequently the most resistant against simulating space conditions as UV-C, X-ray and heavy ions radiation. Despite belonging to the same species, spores from strains Bacillus horneckiae SBP3 and Bacillus horneckiae DSM 23175T responded differently to stresses, which may reflect the adaptation to harsh environmental conditions of the Eolian thermophilic strain. Additional comparisons were made with reference strains used in Astrobiology studies, isolated from spacecraft assembly facilities (B. horneckiae, B. nealsonii and B. pumilus SAFR032), and the biodosimetry strain and space microbiology model organisms B. subtilis 168. Spores of B. horneckiae SBP3 were able to survive stressing conditions (exposition to heat, acid and alkaline stresses, UV-C, X-rays, heavy ions, low pressure plasma, desiccation and hydrogen peroxide), often at higher degree than those of B. subtilis. The results obtained by Raman spectroscopy showed that the damages induced by heat stress to spores are related to the denaturation of proteins, rather than to those of nucleic acids. This finding suggests, that the mechanisms involved to contrast the heat stress are probably related to the thermostability of small-acid soluble proteins in spore-core. The resistance of spores to terrestrial environmental stressors could also be determinant in resisting to space stressors (as UV-C and X-rays radiations, exposure at temperature 95 and 130°C and desiccation stress). Moreover, exopolysaccharides structure and composition, involved in the biofilm formation, could be also considered as a mechanism to protect spores under stress conditions. As bacterial multi-resistant forms, the studied spores are expected to possess novel, unexplored applicative potentials in different contexts, such as new bio-indicators for safety and security in human activities, as well as in Astrobiology, in space exploration missions and “Planetary Protection” programs.

Resistance to space simulating conditions and sporicidal treatments of spores from bacilli of extreme environments origins: implication for Astrobiology.

Resistance to space simulating conditions and sporicidal treatments of spores from bacilli of extreme environments origins: implication for Astrobiology

Zammuto, Vincenzo

Abstract

Microorganisms able to tolerate environmental extremes, or extremophiles, are ideal candidates to extend our knowledge on the limitations for terrestrial life, including sporicidal treatments, and on their ability to survive under conditions mimicking space environments. The spore resistance of bacilli isolated from extreme environments, cold (Antarctic soils) and hot (shallow hydrothermal vents of Eolian Islands, Italy), was evaluated towards environmental stressors (wet- and dry-heat, low and high pH values), sporicidal treatments and stresses simulating space-environments (UV-C and X-rays irradiations, desiccations by low pressure, exposition to oxidizing agents and low pressure plasma), as those from the planet surface of Europa (the satellite of Jupiter), Enceladus (the satellite of Saturn) and Mars. Spores from two thermophilic Eolian strains, Bacillus horneckiae SBP3 (SBP3) and B. licheniformis T14, and a psychrophilic Antarctic strain, B. simplex A43, were frequently the most resistant against simulating space conditions as UV-C, X-ray and heavy ions radiation. Despite belonging to the same species, spores from strains Bacillus horneckiae SBP3 and Bacillus horneckiae DSM 23175T responded differently to stresses, which may reflect the adaptation to harsh environmental conditions of the Eolian thermophilic strain. Additional comparisons were made with reference strains used in Astrobiology studies, isolated from spacecraft assembly facilities (B. horneckiae, B. nealsonii and B. pumilus SAFR032), and the biodosimetry strain and space microbiology model organisms B. subtilis 168. Spores of B. horneckiae SBP3 were able to survive stressing conditions (exposition to heat, acid and alkaline stresses, UV-C, X-rays, heavy ions, low pressure plasma, desiccation and hydrogen peroxide), often at higher degree than those of B. subtilis. The results obtained by Raman spectroscopy showed that the damages induced by heat stress to spores are related to the denaturation of proteins, rather than to those of nucleic acids. This finding suggests, that the mechanisms involved to contrast the heat stress are probably related to the thermostability of small-acid soluble proteins in spore-core. The resistance of spores to terrestrial environmental stressors could also be determinant in resisting to space stressors (as UV-C and X-rays radiations, exposure at temperature 95 and 130°C and desiccation stress). Moreover, exopolysaccharides structure and composition, involved in the biofilm formation, could be also considered as a mechanism to protect spores under stress conditions. As bacterial multi-resistant forms, the studied spores are expected to possess novel, unexplored applicative potentials in different contexts, such as new bio-indicators for safety and security in human activities, as well as in Astrobiology, in space exploration missions and “Planetary Protection” programs.
Microorganisms able to tolerate environmental extremes, or extremophiles, are ideal candidates to extend our knowledge on the limitations for terrestrial life, including sporicidal treatments, and on their ability to survive under conditions mimicking space environments. The spore resistance of bacilli isolated from extreme environments, cold (Antarctic soils) and hot (shallow hydrothermal vents of Eolian Islands, Italy), was evaluated towards environmental stressors (wet- and dry-heat, low and high pH values), sporicidal treatments and stresses simulating space-environments (UV-C and X-rays irradiations, desiccations by low pressure, exposition to oxidizing agents and low pressure plasma), as those from the planet surface of Europa (the satellite of Jupiter), Enceladus (the satellite of Saturn) and Mars. Spores from two thermophilic Eolian strains, Bacillus horneckiae SBP3 (SBP3) and B. licheniformis T14, and a psychrophilic Antarctic strain, B. simplex A43, were frequently the most resistant against simulating space conditions as UV-C, X-ray and heavy ions radiation. Despite belonging to the same species, spores from strains Bacillus horneckiae SBP3 and Bacillus horneckiae DSM 23175T responded differently to stresses, which may reflect the adaptation to harsh environmental conditions of the Eolian thermophilic strain. Additional comparisons were made with reference strains used in Astrobiology studies, isolated from spacecraft assembly facilities (B. horneckiae, B. nealsonii and B. pumilus SAFR032), and the biodosimetry strain and space microbiology model organisms B. subtilis 168. Spores of B. horneckiae SBP3 were able to survive stressing conditions (exposition to heat, acid and alkaline stresses, UV-C, X-rays, heavy ions, low pressure plasma, desiccation and hydrogen peroxide), often at higher degree than those of B. subtilis. The results obtained by Raman spectroscopy showed that the damages induced by heat stress to spores are related to the denaturation of proteins, rather than to those of nucleic acids. This finding suggests, that the mechanisms involved to contrast the heat stress are probably related to the thermostability of small-acid soluble proteins in spore-core. The resistance of spores to terrestrial environmental stressors could also be determinant in resisting to space stressors (as UV-C and X-rays radiations, exposure at temperature 95 and 130°C and desiccation stress). Moreover, exopolysaccharides structure and composition, involved in the biofilm formation, could be also considered as a mechanism to protect spores under stress conditions. As bacterial multi-resistant forms, the studied spores are expected to possess novel, unexplored applicative potentials in different contexts, such as new bio-indicators for safety and security in human activities, as well as in Astrobiology, in space exploration missions and “Planetary Protection” programs.
Bacillus, Spores, Astrobiology, Extremophiles, Radiation, Resistance
Resistance to space simulating conditions and sporicidal treatments of spores from bacilli of extreme environments origins: implication for Astrobiology.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10447/338497
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