Effects of Ionizing Radiation and Long-Term Storage on Hydrated vs. Dried Cell Samples of Extremophilic Microorganisms

Abstract

A main factor hampering life in space is represented by high atomic number nuclei and energy (HZE) ions that constitute about 1% of the galactic cosmic rays. In the frame of the “STARLIFE” project, we accessed the Heavy Ion Medical Accelerator (HIMAC) facility of the National Institute of Radiological Sciences (NIRS) in Chiba, Japan. By means of this facility, the extremophilic species Haloterrigena hispanica and Parageobacillus thermantarcticus were irradiated with high LET ions (i.e., Fe, Ar, and He ions) at doses corresponding to long permanence in the space environment. The survivability of HZE-treated cells depended upon either the storage time and the hydration state during irradiation; indeed, dry samples were shown to be more resistant than hydrated ones. With particular regard to spores of the species P. thermantarcticus, they were the most resistant to irradiation in a water medium: an analysis of the changes in their biochemical fingerprinting during irradiation showed that, below the survivability threshold, the spores undergo to a germination-like process, while for higher doses, inactivation takes place as a consequence of the concomitant release of the core’s content and a loss of integrity of the main cellular components. Overall, the results reported here suggest that the selected extremophilic microorganisms could serve as biological model for space simulation and/or real space condition exposure, since they showed good resistance to ionizing radiation exposure and were able to resume cellular growth after long-term storage.

Comparative Genomics and Directed Evolution Reveal Genetic Determinants of Extreme UVC Radiation Tolerance in Bacteria Recovered from the Stratosphere

“…Desiccation-and radio-tolerance phenotypes frequently co-occur in extremophilic bacteria and archaea (76)(77)(78)(79)(80)(81)(82)(83)(84). Given that the acute doses to which radiotolerant species are resistant greatly exceed natural ionizing radiation sources on Earth, there is no evolutionary basis for ionizing radiation resistance to arise through natural selection.…”

The effect of aboveground long-term low-dose ionizing radiation on soil microbial diversity and structure

“…However, short-term and high-dose radiation has a sustained and irreversible impact on the composition, distribution, and metabolic pathways of microbial communities (Mohammad et al, 2019). The composition and functional integrity of biofilms are affected as the radiation causes single-strand or double-strand DNA breakages, denaturation of related proteins, and the reduction or inactivation of some enzymes (Romano et al, 2022). Few studies have investigated the effects of low-dose radiation on microorganisms.…”

Ion beam nanoengineering of surfaces for molecular detection using surface enhanced Raman scattering

“…In recent years, there have been many studies on thin films containing plasmonic nanostructures that are good substrates for ultrasensitive detection of chemical/biological species using the surface enhanced Raman scattering (SERS) technique. [1][2][3][4] Generally, synthesis of such thin film-based SERS substrates involves complicated chemistry routes with a possibility of introducing chemical residues as contaminants leading to the deterioration of SERS sensitivity and selectivity. Furthermore, there are several ion beam based and other physical techniques such as ion beam implantation/ irradiation/sputtering, focused ion beam (FIB), electron beam, multi-tip and laser induced nanostructuring of the surfaces for fabricating highly sensitive SERS substrates.…”