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Spore-Forming Thermophilic Bacterium within Artificial Meteorite Survives Entry into the Earth's Atmosphere on FOTON-M4 Satellite Landing Module.

Slobodkin A, Gavrilov S, Ionov V, Iliyin V - PLoS ONE (2015)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.

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.

No MeSH data available.


Related in: MedlinePlus

Interior of the test basalt disc (Disc #1) after the flight.The back side of the disc with the undisturbed wells and the wells without the seals is shown.
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pone.0132611.g005: Interior of the test basalt disc (Disc #1) after the flight.The back side of the disc with the undisturbed wells and the wells without the seals is shown.

Mentions: The temperature during the atmospheric transit was not instrumentally recorded but was high enough to melt the surface of basalt (melting temperature: 1,100–1,250°C) (Fig 4). After the landing, some wells in test discs #1 and #2 had lost their seals; however the dried microbial cultures within the wells were still present (Fig 5). Inoculation of the dried cultures recovered from the wells into a liquid cultivation medium followed by incubation at 65°C for 120 hours resulted in microbial growth and ferrihydrite reduction in 4 of the 24 cultures (Table 1). Further incubation of 20 growth-negative cultures during the next three months did not cause growth and Fe(III) reduction. In orbital (24 wells) and ground (24 wells) control discs, all wells retained their seals, and microbial growth and Fe(III) reduction were observed after inoculation of dried cultures recovered from 48 wells (100% survival). In growth-positive cultures the concentration of the cells after 120 hours was 8–10*107 cells/ml, with 15–20% of the cells containing endospores. The morphology of the cells obtained from the test, orbital control, and ground control was consistent with the original description of T. siderophilus [23] (Fig 6). The culture recovered from the undisturbed well of disc #1 was capable of sustainable growth and Fe(III) reduction (Fig 7). After three subsequent 5% (v/v) transfers, specific rates of growth and Fe(II) production of the culture survived the atmospheric entry and the cultures recovered from orbital and ground controls were equal within the range of statistical error (Table 2). A nucleotide sequence of the 16S rRNA gene (1562 b.p.) of the culture that survived the atmospheric entry was 100% identical to the type strain of T. siderophilus (GenBank Accession NZ_CM001486). The sequence has been deposited in GenBank under accession number KR736354. Thus the morphological and physiological characteristics as well as a nucleotide sequence of the 16S rRNA gene of the culture survived the atmospheric entry were identical to the type strain of T. siderophilus SR4T loaded into the artificial meteorite before the flight.


Spore-Forming Thermophilic Bacterium within Artificial Meteorite Survives Entry into the Earth's Atmosphere on FOTON-M4 Satellite Landing Module.

Slobodkin A, Gavrilov S, Ionov V, Iliyin V - PLoS ONE (2015)

Interior of the test basalt disc (Disc #1) after the flight.The back side of the disc with the undisturbed wells and the wells without the seals is shown.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4494708&req=5

pone.0132611.g005: Interior of the test basalt disc (Disc #1) after the flight.The back side of the disc with the undisturbed wells and the wells without the seals is shown.
Mentions: The temperature during the atmospheric transit was not instrumentally recorded but was high enough to melt the surface of basalt (melting temperature: 1,100–1,250°C) (Fig 4). After the landing, some wells in test discs #1 and #2 had lost their seals; however the dried microbial cultures within the wells were still present (Fig 5). Inoculation of the dried cultures recovered from the wells into a liquid cultivation medium followed by incubation at 65°C for 120 hours resulted in microbial growth and ferrihydrite reduction in 4 of the 24 cultures (Table 1). Further incubation of 20 growth-negative cultures during the next three months did not cause growth and Fe(III) reduction. In orbital (24 wells) and ground (24 wells) control discs, all wells retained their seals, and microbial growth and Fe(III) reduction were observed after inoculation of dried cultures recovered from 48 wells (100% survival). In growth-positive cultures the concentration of the cells after 120 hours was 8–10*107 cells/ml, with 15–20% of the cells containing endospores. The morphology of the cells obtained from the test, orbital control, and ground control was consistent with the original description of T. siderophilus [23] (Fig 6). The culture recovered from the undisturbed well of disc #1 was capable of sustainable growth and Fe(III) reduction (Fig 7). After three subsequent 5% (v/v) transfers, specific rates of growth and Fe(II) production of the culture survived the atmospheric entry and the cultures recovered from orbital and ground controls were equal within the range of statistical error (Table 2). A nucleotide sequence of the 16S rRNA gene (1562 b.p.) of the culture that survived the atmospheric entry was 100% identical to the type strain of T. siderophilus (GenBank Accession NZ_CM001486). The sequence has been deposited in GenBank under accession number KR736354. Thus the morphological and physiological characteristics as well as a nucleotide sequence of the 16S rRNA gene of the culture survived the atmospheric entry were identical to the type strain of T. siderophilus SR4T loaded into the artificial meteorite before the flight.

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

Affiliation: Winogradsky Institute of Microbiology, Russian Academy of Sciences, Prospect 60-letiya Oktyabrya 7/2, 117312 Moscow, Russia.

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.

No MeSH data available.


Related in: MedlinePlus