title: Survival of microorganisms in space: a review.
abstract: Spores of Bacillus subtilis were exposed to selected factors of space (vacuum, solar UV radiation, heavy ions of cosmic radiation), and their response was studied after recovery. These investigations were supplemented by ground-based studies under simulated space conditions. The vacuum of space did not inactivate the spores. However, vacuum-induced structural changes in the  DNA, and probably in the proteins, caused a supersensitivity to solar UV radiation. This phenomenon is caused by the production of specific photoproducts in DNA and protein, which cannot be removed by normal cellular repair processes. In vegetative  bacterial cells, exposed to vacuum, cell dehydration led to damage of the cell membrane, which could be partly repaired during subsequent incubation. The high local effectiveness of the cosmic heavy ions further decreases the chance that spores can survive for any length of time in space. Nonetheless, a spore travelling through space and protected from ultraviolet radiation could possibly survive an interplanetary journey. Such a situation favors panspermia as a possible explanation for the origin of life.
authors.affiliation: DFVLR, Institut fur Flugmedizin, Abt. Biophysik, Frankfurt/Main, FRG.
authors.forename: G
authors.initials: G
authors.lastname: Horneck
mesh_terms: D001412:Bacillus subtilis / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects*; D003359:Cosmic Radiation; D004307:Dose-Response Relationship, Radiation; D004926:Escherichia coli / Q000254:growth & development / Q000502:physiology / Q000528:radiation effects*; D005118:Extraterrestrial Environment; D020450:Heavy Ions; D018499:Linear Energy Transfer; D000069497:Origin of Life; D011836:Radiation Tolerance; D013026:Space Flight; D013171:Spores, Bacterial; D014466:Ultraviolet Rays; D014618:Vacuum