Extremophile survives the transient pressures associated with impact-induced ejection from Mars

Abstract Large-scale impacts are ubiquitous in the solar system, and the likelihood of survival of organisms after an impact event plays a key role in planetary protection, the search for extraterrestrial life, and the assessment of the panspermia hypothesis. Impacts generate very high stresses for short times, resulting in extreme pressures and high rates of loading. Can microorganisms survive such extreme conditions? Directly assessing the resilience of microorganisms subjected to impact stresses has been difficult because of challenges in experimental design for these extreme conditions, together with the choices of biological model system. Here, we describe an experimental approach that allows us to subject microorganisms to controlled extreme pressures for short times, recover these impacted microorganisms, and then assess their rates of survival, structural damage, and their molecular response to these extreme events. We focused on Deinococcus radiodurans, an extremophile that is known to survive space-like conditions. Our results suggested that microorganisms can survive much more extreme conditions than previously thought, potentially surviving conditions that result in the formation of ejecta that can move across planetary systems. We demonstrated that the extremophile D. radiodurans has remarkably high survivability and viability after being subjected to pressures of up to 3 GPa. As the pressure increases, D. radiodurans exhibited indicators of increased biological stress, as determined by the transcriptional analysis of impacted samples. The work has significant consequences for considerations of planetary protection, spacecraft mission design, our understanding of where we might find extraterrestrial life, and lithopanspermia.