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Extremophiles. 2017 Nov;21(6):1057-1067. doi: 10.1007/s00792-017-0966-7. Epub 2017 Oct 9.

100 kGy gamma-affected microbial communities within the ancient Arctic permafrost under simulated Martian conditions.

Author information

1
Lomonosov Moscow State University, GSP-1, Leninskie Gory 1/12, Moscow, 119991, Russia. cheptcov.vladimir@gmail.com.
2
Space Research Institute, Russian Academy of Sciences, 84/32 Profsoyuznaya Str., Moscow, 117997, Russia. cheptcov.vladimir@gmail.com.
3
Lomonosov Moscow State University, GSP-1, Leninskie Gory 1/12, Moscow, 119991, Russia.
4
Space Research Institute, Russian Academy of Sciences, 84/32 Profsoyuznaya Str., Moscow, 117997, Russia.
5
Ioffe Physical-Technical Institute, Russian Academy of Sciences, Polytechnicheskaya Str. 26, St. Petersburg, Russia.
6
S.-Petersburg State Polytechnical University, Polytechnicheskaya Str. 29, St. Peterburg, 195251, Russia.
7
Petersburg Nuclear Physics Institute Named by B.P. Konstantinov of National Research Centre "Kurchatov Institute", Gatchina, 188300, Russia.
8
Institute of Physics and Technology, Ural Federal University, Ekaterinburg, 620002, Russia.

Abstract

This research aimed to investigate the viability and biodiversity of microbial communities within ancient Arctic permafrost after exposure to a gamma-radiation dose of 100 kGy at low temperature (- 50 °C), low pressure (1 Torr) and dehydration conditions. The main objective was to assess the possibility for long-term survival of Earth-bound microorganisms in the subsurface of Martian regolith or inside small space bodies at constant absorption and accumulation of the gamma radiation dose. Investigated microbial communities had shown high resistance to a simulated Martian environment. After irradiation the total count of prokaryotic cells and number of metabolically active bacterial cells remained at the control level, while the number of bacterial CFUs decreased by 2 orders of magnitude, and the number of metabolically active cells of archaea decreased threefold. Besides, the abundance of culturable bacteria after irradiation was kept at a high level: not less than 3.7 × 105 cells/g. Potential metabolic activity of irradiated microbial communities in general were higher than in the control sample. A fairly high biodiversity of bacteria was detected in the exposed sample of permafrost, although the microbial community structure underwent significant changes after irradiation. In particular, actinobacteria populations of the genus Arthrobacter, which was not revealed in the control samples, became predominant in bacterial communities following the exposure. The results of the study testify that long-term preservation of microbial life inside Martian permafrost is possible. The data obtained can also be evaluated from the perspective of the potential for discovering viable Earth-bound microorganisms on other objects in the Solar system and inside of small bodies in outer space.

KEYWORDS:

Ancient Arctic permafrost; Astrobiology; Biodiversity; Gamma radiation; Low pressure; Low temperature; Mars regolith; Microorganisms

PMID:
28993922
DOI:
10.1007/s00792-017-0966-7
[Indexed for MEDLINE]

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