Data from: Survival limits of yeasts and other extremophilic microorganisms with relevance for planetary protection of the icy moons
Data files
Aug 09, 2025 version files 93.48 KB
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README.md
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Relative_survival_to_exposure.zip
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Abstract
Investigating the survival limits of extremophilic microorganisms exposed to simulated space conditions can shed light on the ability of terrestrial microorganisms to survive and propagate on other planetary bodies. Although microbes can be found in all environmental niches on Earth, this study focuses mainly on psychrophilic and psychrotolerant microorganisms (prokaryotes and eukaryotes) which have been isolated from locations of interest such as icy moon analogue environments and cleanrooms, and which might be of concern for forward planetary protection. Our research aimed to reproduce conditions for microorganisms on spacecraft travelling to the outer solar system, which could contaminate the icy moon’s subsurface oceans. The microorganisms were grown under oligotrophic conditions in minimal media supplemented with only a single carbon source and exposed to extreme conditions, in terms of temperature and radiation, as they occur during space travel to the outer solar system. Our results, in combination with future metagenome data and phenotype prediction tools, will allow the identification of planetary protection-relevant microorganisms in spacecraft assembly cleanrooms and on spacecraft and support the development of target-oriented planetary protection constraints for missions to the icy moons.
Dataset DOI: 10.5061/dryad.70rxwdc7r
Description of the data and file structure
Data from: Survival of extremophilic microorganisms to icy moon simulated conditions
Description of the data and file structure
The data reported here was obtained by determining the relative survival (N/N0) of the microorganisms evaluated in our study exposed to icy moon conditions. These include the exposure to freeze and thaw cycles, to freezing at -80°C without cryoprotectants, the exposure to polychromatic UV radiation, UV-C radiation and X-ray radiation. The relative survival was calculated by dividing the number of microbial colony forming units (CFU) post exposure (N) by the CFU of the control condition (N0) un-exposed to the icy moon conditions.
Files and variables
File: Relative_survival_to_exposure.zip
Description:
This folder contains the raw and formatted data in Excel files which can be used to reproduce the analysis.
Freeze and thaw.xlsx: Contains the survival data used for generating the figure showing the freeze (-80°C) and thaw (+25°C) tolerance of the microorganisms used in the study. The data is split into columns (i.e. Cycle number, Relative Survival (N/N0) and Organism) and each row represents a single experimental replicate.
- Cycle number: The number of times the microorganisms were freezed and thawed. 1 cycle is equal to the organisms being frozen and subsequently thawed.
- Relative Survival (N/N0): The value represents the relative survival of each experimental replicate for each organism calculated by dividing the number of microbial colony forming units (CFU) after each cycle (N) by the CFU of the control condition (N0).
- Organism: The name in each row of this column is associated to the cycle number and Relative survival of the same row.
Freezing time.xlsx: Contains data in relation to the time it takes for growth media, air and microbial cells to reach subzero temperatures in the -80°C freezer used in the study. Data is grouped in columns labelled Time (minutes), Temperature (°C) and condition and was collected using a digital thermometer.
- Time (minutes): The time progression, in minutes, when the digital thermometer recorded the temperature.
- Temperature (°C): The temperature each sample was in at the reported timepoint.
- condition: the different samples, growth media, air, and cells.
Freezing.xlsx: Reports the survival data of the different microorganisms exposed to freezing at -80°C. The data is split into columns (i.e. Days frozen, Relative Survival (N/N0) and Organism) and each row represents a single experimental replicate.
- Days frozen: Column reporting the number of days for each microorganisms and for which the relative survival was measured.
- Relative Survival (N/N0): The value represents the relative survival of each experimental replicate for each microorganism calculated by dividing the number of microbial colony forming units (CFU) at each measurement timepoint (N) by the CFU of the control condition (N0).
- Organism: The name in each row of this column is associated to the cycle number and Relative survival of the same row.
Polychromatic UV.xlsx: Reports the survival data of the microorganisms exposed to polychromatic UV radiation (200-400 nm) as described in our study.
- Dose (J/m2): The exposure fluence for each microorganism for which the relative survival was calculated.
- Relative Survival (N/N0): The value represents the relative survival of each experimental replicate for each microorganism calculated by dividing the number of microbial colony forming units (CFU) for each fluence (N) by the CFU of the control condition (N0).
- Organism: The name in each row of this column is associated to the cycle number and Relative survival of the same row.
UV-C.xlsx: Reports the survival data of the microorganisms exposed to UV-C radiation (254 nm) as described in our study.
- Dose (J/m2): The exposure fluence for each microorganism for which the relative survival was calculated.
- Relative Survival (N/N0): The value represents the relative survival of each experimental replicate for each microorganism calculated by dividing the number of microbial colony forming units (CFU) for each fluence (N) by the CFU of the control condition (N0).
- Organism: The name in each row of this column is associated to the cycle number and Relative survival of the same row.
X-ray.xlsx: Reports the survival data of the microorganisms exposed to X-ray radiation as described in our study.
- Dose (Gy): The exposure dose for each microorganism for which the relative survival was calculated.
- Relative Survival (N/N0): The value represents the relative survival of each experimental replicate for each microorganism calculated by dividing the number of microbial colony forming units (CFU) for each dose (N) by the CFU of the control condition (N0).
- Organism: The name in each row of this column is associated to the cycle number and Relative survival of the same row.
Code/software
All data processing for the purpose of image generation (Python_code_for_figure_generation.txt) was performed using the Python interpreter (Python interpreter version 3.11.0 (2024-11-24) the original interpreter can be accessed on python.org (https://www.python.org/downloads/release/python-3110/)).
Image generation was performed using the following packages in the python interpreter:
- numpy (numpy version 1.23.5 (2022-11-20)) a package used for python scientific computing
- pandas (pandas version 1.5.2(2022-11-22)) a package used for tabular data processing
- seaborn (seaborn version 0.12.1 (2022-10)) a data visualization library
- matplotlib (matplotlib version 3.6.2 (2022-11-3)) a library used for data visualization in Python
Access information
Other publicly accessible locations of the data:
- NA
Data was derived from the following sources:
- NA
Methods included growth of microorganisms in minimal media, exposure to desiccation, polychromatic UV, UV-C and X-ray radiation.