DOI: 10.5061/dryad.70rxwdc7r
title: Data from: Survival limits of yeasts and other extremophilic microorganisms with relevance for planetary protection of the icy moons

description: 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.
description: Methods included growth of microorganisms in minimal media,
 exposure to desiccation, polychromatic UV, UV-C and X-ray
 radiation.
description: # Data from: Survival limits of yeasts and other extremophilic
 microorganisms with relevance for planetary protection of the icy moons
 Dataset DOI: [10.5061/dryad.70rxwdc7r](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/](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