The Efficacy of Bacterial SWITCH Test for Determination of Cyto- and Genotoxicity Induced by X-Rays and Simulated Space Radiation Qualities

Abstract

The principal concerns for astronauts exposure to space radiation is the cancer. Astronauts are exposed to different quality of radiation in space than they receive in earth. In this study, the recombinant SWITCH test, developed by bio-diagnostics group at German Aerospace Center (DLR) was used to analyze bacterial inactivation and mutation induction by ionizing radiation in parallel to different chemicals in the same cell within short time. On the other hand, Chemical dosimetry was also performed for the determination oxidative damage from different qualities of radiations of 200 kV X-rays. The results obtained from chemical dosimetry clearly show that no difference between physical and chemical dosimetry as indicated by similar oxidative damage. Likewise the results obtained from SWITCH test treated with chemicals (Bleomycin and hydrogen peroxide), different quality of 200 kV X- rays and heavy ions (75 MeV/u carbon with LET 37 keV/μm and 95 MeV/u oxygen with LET 52 keV/μm) show that the bacterial strain pSWITCH Salmonella typhimurium TA1535 shows greater sensitiveness towards tested chemical and ionizing radiation than pSWITCH Escherichia coli C600. The inactivation of bacteria (cytotoxicity) by number of hits (Particles per cm-²) depends on LET and genotoxic response seems to be inversely related to LET.