EXPERIMENT RECORD N° 7051
Cytos 2
  1. 1982 • Salyut 7 (Soyuz T-6) French/Soviet Mission
Life Sciences:
  • Cell and Molecular Biology
Olivier Minster
olivier.minster@esa.int
R. Tixador (1), N. Moatti (1), L. Lapchine (1), G. Gasset (1), B. Eche (1)
(1)  
Faculte de Medicine Toulouse-Purpan
Laboratoire de Biology Medical
37 allees Jules Guesde
31073 Toulouse
FRANCE
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. Experiment Specimens: 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.
[1]  
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.
[2]  
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.
[3]  
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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Fig. 1

Fig. 2
 
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