title: Spore-Forming Thermophilic Bacterium within Artificial Meteorite Survives Entry into the Earth's Atmosphere on FOTON-M4 Satellite Landing Module.
abstract: One of the key conditions of the lithopanspermia hypothesis is that microorganisms situated within meteorites could survive hypervelocity entry from space through the Earth's atmosphere. So far, all experimental proof of this possibility has been based on tests with sounding rockets which do not reach the transit velocities of natural meteorites. We explored the survival of the spore-forming thermophilic anaerobic bacterium, Thermoanaerobacter siderophilus, placed within 1.4-cm thick basalt discs fixed on the exterior of a space capsule (the METEORITE experiment on the FOTON-M4 satellite). After 45 days of orbital flight, the landing module of the space vehicle returned to Earth. The temperature during the atmospheric transit was high enough to melt the surface of basalt. T. siderophilus survived the entry; viable cells were recovered from 4 of 24 wells loaded with this microorganism. The identity of the strain was confirmed by 16S rRNA gene sequence and physiological tests. This is the first report on the survival of a lifeform within an artificial meteorite after entry from space orbit through Earth's atmosphere at a velocity that closely approached the velocities of natural meteorites. The characteristics of the artificial meteorite and the living object applied in this study can serve as positive controls in further experiments on testing of different organisms and conditions of interplanetary transport.
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.
authors.forename: Alexander
authors.initials: A
authors.lastname: Slobodkin
authors.affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.
authors.forename: Sergey
authors.initials: S
authors.lastname: Gavrilov
authors.affiliation: Russian Federation State Research Center Institute of Biomedical Problems, Russian Academy of Sciences, Khoroshevskoe Shosse 76 A, 123007 Moscow, Russia.
authors.forename: Victor
authors.initials: V
authors.lastname: Ionov
authors.affiliation: Russian Federation State Research Center Institute of Biomedical Problems, Russian Academy of Sciences, Khoroshevskoe Shosse 76 A, 123007 Moscow, Russia.
authors.forename: Vyacheslav
authors.initials: V
authors.lastname: Iliyin
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology; D001272:Atmosphere; D018534:Earth, Planet; D005118:Extraterrestrial Environment; D005296:Ferrous Compounds / Q000378:metabolism; D006358:Hot Temperature; D019110:Meteoroids; D050296:Microbial Viability; D017640:Silicates / Q000737:chemistry; D013026:Space Flight; D013171:Spores, Bacterial / Q000502:physiology; D046968:Thermoanaerobacter / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors
chemical_list: D005296:Ferrous Compounds; D017640:Silicates; C060346:basalt