Survival of Radioresistant Bacteria on Europa’s Surface after Pulse Ejection of Subsurface Ocean Water

Abstract

We briefly present preliminary results of our study of the radioresistant bacteria in a low temperature and pressure and high-radiation environment and hypothesize the ability of microorganisms to survive extraterrestrial high-radiation environments, such as the icy surface of Jupiter’s moon, Europa. In this study, samples containing a strain of Deinococcus radiodurans VKM B-1422T embedded into a simulated version of Europa’s ice were put under extreme environmental (−130 °C, 0.01 mbar) and radiation conditions using a specially designed experimental vacuum chamber. The samples were irradiated with 5, 10, 50, and 100 kGy doses and subsequently studied for residual viable cells. We estimate the limit of the accumulated dose that viable cells in those conditions could withstand at 50 kGy. Combining our numerical modelling of the accumulated dose in ice with observations of water eruption events on Europa, we hypothesize that in the case of such events, it is possible that putative extraterrestrial organisms might retain viability in a dormant state for up to 10,000 years, and could be sampled and studied by future probe missions.

Living at the Extremes: Extremophiles and the Limits of Life in a Planetary Context

“…McCord and Castillo-Rogez, 2018; McCord and Zambon, 2019; Neveu and Desch, 2015;Villarreal et al, 2017;Vu et al, 2017;Zolotov, 2009 Ion sputtering of the surface; potential water plumes ; O2; trace amounts of sodium and potassium Cassidy et al, 2013;Chyba and Phillips, 2001;Hand and Carlson, 2015;Jones et al, 2018;Kattenhorn and Prockter, 2014;Kimura and Kitadai, 2015;Marion et al, 2005;Martin and McMinn, 2018;McGrath et al, 2009;Muñoz-Iglesias et al, 2013;Noell et al, 2015;Pavlov et al, 2018;Soderlund et al, 2014;Spencer et al, 1999;Teolis et al, 2017;Travis et al, 2012;Vance et al, 2016;Zolotov and Kargel, 2009 Surface (icy shell) -187 --141 nr 0. Potential for wide range q 0.1 -30 r <3.5 Likely contains Mg 2+ , SO4 2-, Na + , Cl -; oxidants and simple organics a -Thermosphere can be as cold as -173ºC (Bertaux et al, 2007); the upper-to-middle cloud layers are between -40-60ºC (Cockell, 1999) b -Acid concentration in upper cloud layer is 81%, in lower layers up to 98% (Cockell, 1999) c -Up to 11 MPa in a deep depression (Basilevsky and Head, 2003) d -Summer air temperatures on Mars near the equator can reach a maximum of 35ºC (Longstaff, 2014) e -Measured by the Phoenix Mars Lander Wet Chemistry Laboratory at the northern plains of the Vastitas Borealis (Hecht et al, 2009) f -Liquid water may have had water activity > 0.95 (Fairén et al, 2009) g -Calculated temperature at a depth of 1-30 km (Sinha2017, Jones2011); at a depth ~310 km, the calculated temperature is <427ºC (Jones 2011); the Martian core has temperature 1527ºC…”

Effects of Radiation Intensity, Mineral Matrix, and Pre-Irradiation on the Bacterial Resistance to Gamma Irradiation under Low Temperature Conditions

“…There is quite a lot of information on the activity of various metabolic processes in microbial cells at temperatures as low as −40 °C [ 6 , 68 , 69 , 70 ], and in this regard, the implementation of any metabolic processes at −50 °C (the temperature in our experiment), in general, seems possible. But even if at such a temperature the damage repair occurs, it must be extremely slow, given the known data on low rate of metabolic processes at low temperatures [ 69 , 70 , 71 ] and probably does not significantly contribute to the change in survival, taking into account the duration of the radiation dose accumulation (0.25 h and 1.25 h for 4 kGy/h and 0.8 kGy/h, respectively). In addition to low temperatures, possible metabolic activity could also be inhibited due to low pressure.…”

Factors in Protobiomonomer Selection for the Origin of the Standard Genetic Code

“…In laboratory simulation experiments, UV irradiation of a cold pyrimidine (C 4 H 4 N 2 ) mixture with H 2 O, NH 3 , and CH 4 produced pyrimidine nitrogenous bases, and irradiation of a purine (C 5 H 4 N 4 ) mixture with H 2 O and NH 3 gave rise to purine bases (Materese et al 2013(Materese et al , 2017. Analysis of limiting conditions of extremophilic habitats in the Earth cryosphere suggests that extraterrestrial cryolife might exist within the solar system, first of all, on Mars and on larger moons of Jupiter and Saturn (Beaty et al 2006;Russell and Kanik 2010;Siddiqui et al 2013;McKay 2016;Schulze-Makuch et al 2017;Martin and McMinn 2018;Pavlov et al 2019;Saralov 2019a).…”

“…Cytosine has not been detected in comets or meteorites (Pearce and Pudritz 2015). The hydrophobicity of nucleobases is closely related to the phenomenon of resonance (Pauling and Pauling 1975). Among these bases, the highest energy of resonance is exhibited by adenine (6-aminopurine, C 5 H 5 N 5 ), a stable molecule that lacks oxygen atoms.…”

“…The transition between the resonance forms is accompanied by the redistribution of valence electrons, while all nuclei remain in their places (Metzler 1977). Owing to the presence of several hybrid valence structures, these dissociating molecules acquire additional stabilizing energy of resonance (Pauling and Pauling 1975).…”