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Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions

Frösler, Jan and Panitz, Corinna and Wingender, Jost and Flemming, Hans-Curt and Rettberg, Petra (2017) Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions. Astrobiology, 17 (5), pp. 431-447. Mary Ann Liebert Inc.. DOI: 10.1089/ast.2015.1431 ISSN 1531-1074

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Official URL: http://dx.doi.org/10.1089/ast.2015.1431

Abstract

Biofilm formation represents a successful survival strategy for bacteria. In biofilms, cells are embedded in a matrix of extracellular polymeric substances (EPS). As they are often more stress-tolerant than single cells, biofilm cells might survive the conditions present in space and on Mars. To investigate this topic, the bacterium Deinococcus geothermalis was chosen as a model organism due to its tolerance toward desiccation and radiation. Biofilms cultivated on membranes and, for comparison, planktonically grown cells deposited on membranes were air-dried and exposed to individual stressors that included prolonged desiccation, extreme temperatures, vacuum, simulated martian atmosphere, and UV irradiation, and they were exposed to combinations of stressors that simulate space (desiccation + vacuum + UV) or martian (desiccation + Mars atmosphere + UV) conditions. The effect of sulfatic Mars regolith simulant on cell viability during stress was investigated separately. The EPS produced by the biofilm cells contained mainly polysaccharides and proteins. To detect viable but nonculturable (VBNC) cells, cultivation-independent viability indicators (membrane integrity, ATP, 16S rRNA) were determined in addition to colony counts. Desiccation for 2 months resulted in a decrease of culturability with minor changes of membrane integrity in biofilm cells and major loss of membrane integrity in planktonic bacteria. Temperatures between -25°C and +60°C, vacuum, and Mars atmosphere affected neither culturability nor membrane integrity in both phenotypes. Monochromatic (254 nm; ‡1 kJ m⁻²) and polychromatic (200–400 nm; >5.5 MJ m⁻² for planktonic cells and >270 MJ m⁻² for biofilms) UV irradiation significantly reduced the culturability of D. geothermalis but did not affect cultivation-independent viability markers, indicating the induction of a VBNC state in UV-irradiated cells. In conclusion, a substantial proportion of the D. geothermalis population remained viable under all stress conditions tested, and in most cases the biofilm form proved advantageous for surviving space and Mars-like conditions.

Item URL in elib:https://elib.dlr.de/112537/
Document Type:Article
Title:Survival of Deinococcus geothermalis in Biofilms under Desiccation and Simulated Space and Martian Conditions
Authors:
AuthorsInstitution or Email of AuthorsAuthors ORCID iD
Frösler, JanBiofilm Centre, University of Duisburg-Essen, Essen, Germany.UNSPECIFIED
Panitz, CorinnaUniklinik/RWTH Aachen, Institute of Pharmacology and Toxicology, Aachen, Germany.https://orcid.org/0000-0002-6740-761X
Wingender, JostBiofilm Centre, University of Duisburg-Essen, Essen, Germany.UNSPECIFIED
Flemming, Hans-CurtBiofilm Centre, University of Duisburg-Essen, Essen, Germany.UNSPECIFIED
Rettberg, Petraradiation biology department, institute of aerospace medicine, german aerospace center (dlr), cologne, germany.https://orcid.org/0000-0003-4439-2395
Date:2017
Journal or Publication Title:Astrobiology
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:17
DOI :10.1089/ast.2015.1431
Page Range:pp. 431-447
Publisher:Mary Ann Liebert Inc.
ISSN:1531-1074
Status:Published
Keywords:Biofilms, Desiccation, UV Radiation, Mars, Lithopanspermia
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Research under Space Conditions
DLR - Research area:Raumfahrt
DLR - Program:R FR - Forschung unter Weltraumbedingungen
DLR - Research theme (Project):R - Vorhaben Strahlenbiologie
Location: Köln-Porz
Institutes and Institutions:Institute of Aerospace Medicine > Radiation Biology
Deposited By: Kopp, Kerstin
Deposited On:14 Jun 2017 13:26
Last Modified:06 Sep 2019 15:23

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