TY - JOUR
T1 - The effects of time-since-activation through saltation and dose on the toxicity of Mars-analogous abraded basalt and the bacterial transcriptomic response
AU - Crossfield, Gabriel
AU - Finster, Kai
N1 - Publisher Copyright:
© The Author(s) 2025.
PY - 2025/12
Y1 - 2025/12
N2 - Any life on Mars has to contest with harsh ionising radiation conditions, a lack of bioavailable liquid water, and the oxidising effects of the Martian regolith. The latter is in part due to ˙OH production during wind-driven saltation leading to triboelectric charging and formation of radicals on newly exposed surfaces, mediated by the high Fe2+ levels. Extracellular ˙OH can oxidise outer-membrane proteins and membrane lipids, leading to lipid peroxidation and possibly cell death. Previous findings report > 99% bacterial cell death in response to a fixed dose of 0.5 g ml−1 of Mars-analogous abraded basalt that had recently undergone simulated saltation. Here, Pseudomonas putida was exposed to a range of doses (0.5 g ml−1, 0.1 g ml−1, 0.05 g ml−1) of abraded basalt which had undergone simulated saltation 7 years earlier. Toxicity appeared to be reduced when compared to recently abraded basalt. The highest dose was the most lethal, while there was no significant difference between the medium and low doses. However, CFU counts tended to increase over a 24 h period, following the initial decline. The underlying transcriptomic response was analysed, revealing a switch from free-swimming cells to biofilm formation. Regulation of intracellular Fe2+ levels through multiple mechanisms occurred, as well as amino acid metabolism genes playing a role in combating oxidative stress. The transcriptomic response further pointed to increased membrane permeability and oxidation of outer membrane proteins as key stresses encountered when exposed to Mars-analogous abraded basalt. Overall, we demonstrate that Mars-analogous basalt toxicity varies with time-since-activation through saltation and dose, unveiled by the complex transcriptomic response.
AB - Any life on Mars has to contest with harsh ionising radiation conditions, a lack of bioavailable liquid water, and the oxidising effects of the Martian regolith. The latter is in part due to ˙OH production during wind-driven saltation leading to triboelectric charging and formation of radicals on newly exposed surfaces, mediated by the high Fe2+ levels. Extracellular ˙OH can oxidise outer-membrane proteins and membrane lipids, leading to lipid peroxidation and possibly cell death. Previous findings report > 99% bacterial cell death in response to a fixed dose of 0.5 g ml−1 of Mars-analogous abraded basalt that had recently undergone simulated saltation. Here, Pseudomonas putida was exposed to a range of doses (0.5 g ml−1, 0.1 g ml−1, 0.05 g ml−1) of abraded basalt which had undergone simulated saltation 7 years earlier. Toxicity appeared to be reduced when compared to recently abraded basalt. The highest dose was the most lethal, while there was no significant difference between the medium and low doses. However, CFU counts tended to increase over a 24 h period, following the initial decline. The underlying transcriptomic response was analysed, revealing a switch from free-swimming cells to biofilm formation. Regulation of intracellular Fe2+ levels through multiple mechanisms occurred, as well as amino acid metabolism genes playing a role in combating oxidative stress. The transcriptomic response further pointed to increased membrane permeability and oxidation of outer membrane proteins as key stresses encountered when exposed to Mars-analogous abraded basalt. Overall, we demonstrate that Mars-analogous basalt toxicity varies with time-since-activation through saltation and dose, unveiled by the complex transcriptomic response.
UR - http://www.scopus.com/inward/record.url?scp=105005093263&partnerID=8YFLogxK
U2 - 10.1007/s11084-025-09694-5
DO - 10.1007/s11084-025-09694-5
M3 - Journal article
AN - SCOPUS:105005093263
SN - 2948-2976
SN - 1573-0875
SN - 2214-7047
SN - 2214-7039
VL - 55
JO - Discover Life
JF - Discover Life
IS - 1
M1 - 16
ER -