1982 Salyut 7 (Soyuz T-6) French/Soviet Mission
R. Tixador (1), N. Moatti (1), L. Lapchine (1), G. Gasset (1), B. Eche (1)
Faculte de Medicine Toulouse-Purpan
Laboratoire de Biology Medical
37 allees Jules Guesde
Several experiments carried out in space on various microorganisms cultivated
in vitro showed changes in the cell behaviour. Environmental factors,
prevailing during spaceflight, as microgravity, cosmic radiation and flight
dynamic factors can induce modifications of structure and function in
bacteria, particularly in response to antibiotics. The aim of the experiment
was to test the sensitivity of bacteria, cultivated in vitro, against
antibiotics in microgravity. To test the variations in the antibiotic
sensitivity of bacteria in space, the classic method of measuring the minimal
inhibitory concentration (MIC), allowing to define the minimal concentration
of antibiotics which stops bacterial growth, was used.
Escherichia coli collected from the microflora of French cosmonaut J.L.
Chretien; Staphylococcus aureus collected from the microflora of French
cosmonaut J.L. Chretien.
The bacterial strains were collected from J.L. Chretien, suspended in
physiological water and sealed into glass ampoules. Each plastic bag contained
1.2 ml culture medium API 10 M with various concentrations of the different
antibiotics and one glass ampoule. For Escherichia coli the antibiotics
Colistin and Kanamycin were used, for Staphylococcus aureus the antibiotics
Oxacillin, Chloramphenicol and Erythromycin. The antibiotics were diluted at
five different concentrations on both sides of the MIC. In microg/ml the MIC
concentrations were: 0.16 for Oxacillin, 4.0 for Chloramphenicol, 0.5 for
Erythromycin, 4.0 for Colistin and 4.0 for Kanamycin. Three sets of identical
cultures were used for each antibody and concentration in the flight and
ground control experiment. The composition of each set of seven cultures was:
1. Culture medium + bacteria, 2. Culture medium + antibiotic, 3. Culture
medium + bacteria + 1/4 MIC antibiotic, 4. Culture medium + bacteria + 1/2 MIC
antibiotic, 5. Culture medium + bacteria + MIC antibiotic, 6. Culture medium +
bacteria + 2 MIC antibiotic, 7. Culture medium + bacteria + 4 MIC antibiotic.
The cultures were stored and transported at 4 deg C to the Soyuz station.
There they were transferred into the incubator at 37 deg C. The experiment was
started by breaking the glass ampoules, thus inoculating the cultures in the
plastic bags. The final concentration at inoculum was 2.5x10E5 bacteria/ml.
The first observation of the culture colours was done 20 hours after the
inoculation, the second 4 hours later. The reading was based on the culture
colour, changing from red to yellow by turning a pH marker (phenol red)
induced by the acidification of the culture medium which follows the use of
glucose during bacterial growth. After the experiment, the cultures were
stored at 4 deg C and returned to Earth. The ground control experiment was
performed simultaneously in a laboratory in Moscow.
An increase in the resistance of the bacteria to antibiotics was found in
microgravity. The increase was particularly significant in Escherichia coli
(Fig. 1 ) and lower in Staphylococcus aureus (Fig. 2
). Postflight investigation of cells cultivated in space
without antibiotics, and developed after recovery in normal culture
conditions, did not show any change in their antibiotic sensitivity and in
their biochemical characters. The observed increase in space was therefore
temporary due to adaptability to weightlessness. Ultrastructural
investigations showed an increase in the number of cells in division in the 0g
samples. In Staphylococcus aureus a very marked increase of the thickness of
the cell wall was found in the 0g cultures.
R. Tixador, G. Richoilley, G. Gasset, J. Templier, J.C. Bes, N. Moatti, L. Lapchine, (1985), "Study of minimal inhibitory concentration of antibiotics on bacteria cultivated in vitro in space (Cytos 2 experiment)", Aviat. Space Environ. Med., Vol. 56, No. 8, pp. 748-751.
R. Tixador et al., (1984), "Study of antibiotics sensitivity and ultrastructure of bacteria performed the orbital station Salyut 7 (Cytos 2 experiment)", Innov. Tech. Biol., Vol. 5, pp. 17-25.
L. Lapchine, N. Moatti, G. Richoilley, J. Templier, G. Gasset, R. Tixador, (1987), "Antibiotic activity in space, results and hypothesis", Proc. 3rd Eur. Symp. On Life Sciences Research in Space, Graz, Austria, ESA SP-271, pp. 305-306.
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