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Effects of desiccation and freezing on microbial ionizing radiation survivability : considerations for Mars sample returnHorne, William H. ...Increasingly, national space agencies are expanding their goals to include Mars exploration with sample return. To better protect Earth and its biosphere from potential extraterrestrial sources of ... contamination, as set forth in the Outer Space Treaty of 1967, international efforts to develop planetary protection measures strive to understand the danger of cross-contamination processes in Mars sample return missions. We aim to better understand the impact of the martian surface on microbial dormancy and survivability. Radiation resistance of microbes is a key parameter in considering survivability of microbes over geologic times on the frigid, arid surface of Mars that is bombarded by solar and galactic cosmic radiation. We tested the influence of desiccation and freezing on the ionizing radiation survival of six model microorganisms: vegetative cells of two bacteria (Deinococcus radiodurans, Escherichia coli) and a strain of budding yeast (Saccharomyces cerevisiae); and vegetative cells and endospores of three Bacillus bacteria (B. subtilis, B. megaterium, B. thuringiensis). Desiccation and freezing greatly increased radiation survival of vegetative polyploid microorganisms when applied separately, and when combined, desiccation and freezing increased radiation survival even more so. Thus, the radiation survival threshold of polyploid D. radiodurans cells can be extended from the already high value of 25 kGy in liquid culture to an astonishing 140 kGy when the cells are both desiccated and frozen. However, such synergistic radioprotective effects of desiccation and freezing were not observed in monogenomic or digenomic Bacillus cells and endospores, which are generally sterilized by 12 kGy. This difference is associated with a critical requirement for survivability under radiation, that is, repair of genome damage caused by radiation. Deinococcus radiodurans and S. cerevisiae accumulate similarly high levels of the Mn antioxidants that are required for extreme radiation resistance, as do endospores, though they greatly exceed spores in radioresistance because they contain multiple identical genome copies, which in D. radiodurans are joined by persistent Holliday junctions. We estimate ionizing radiation survival limits of polyploid DNA-based life-forms to be hundreds of millions of years of background radiation while buried in the martian subsurface. Our findings imply that forward contamination of Mars will essentially be permanent, and backward contamination is a possibility if life ever existed on Mars.Source: Astrobiology. - ISSN 1531-1074 (Vol. 22, no. 11, 2022, str. 1337-1350)Type of material - article, component partPublish date - 2022Language - englishCOBISS.SI-ID - 127593987
Author
Horne, William H. |
Grebenc, Tine |
Tkavc, Rok |
Gostinčar, Cene |
Gunde-Cimerman, Nina
Topics
ekstremotoleranca |
ionizirajoče sevanje |
bakterije |
glive |
radiacija |
astrobiologija |
Mars |
življenje na drugih planetih |
življenje na Marsu |
ionizing radiation |
life on Mars |
astrobiology |
radiation |
fungi |
bacteria |
radiotolerance
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Author | Horne, William H. ... |
Title | Effects of desiccation and freezing on microbial ionizing radiation survivability : considerations for Mars sample return |
Publication date | 2022-10-31 |
COBISS.SI-ID | 127593987 |
Publication version in repository | Publisher's version |
Publication licence | Creative Commons Attribution 4.0 International |
Embargo | Unidentified |
Project(s) from which the publication was funded
Title | Acronym | Project ID | Funder |
---|---|---|---|
Razgradnja plastike s poliekstremotolerantnimi glivami | J4-2549-2020 |
Javna agencija za znanstvenoraziskovalno in inovacijsko dejavnost Republike Slovenije |
|
Izcedne talne vode kot neizkoriščen vir informacij o biotski raznovrstnosti tal | J4-3098-2021 |
Javna agencija za znanstvenoraziskovalno in inovacijsko dejavnost Republike Slovenije |
|
Molekularno-biološke raziskave mikroorganizmov | P1-0198-2018 |
Javna agencija za znanstvenoraziskovalno in inovacijsko dejavnost Republike Slovenije |
|
Morska in mikrobna biotehnologija | P4-0432-2022 |
Javna agencija za znanstvenoraziskovalno in inovacijsko dejavnost Republike Slovenije |
|
Gozdna biologija, ekologija in tehnologija | P4-0107-2020 |
Javna agencija za znanstvenoraziskovalno in inovacijsko dejavnost Republike Slovenije |
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Database name | Field | Year |
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Horne, William H. | ![]() |
Grebenc, Tine | 21242 |
Tkavc, Rok | 29599 |
Gostinčar, Cene | 25974 |
Gunde-Cimerman, Nina | 05935 |
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