Resistance tests with bacterial strains isolated from spacecraft assembly halls

Abstract

In order to achieve a better knowledge about the presence of microorganisms in Spacecraft Assembly Facilities that are able to resist potential hostile conditions, different tests on survival were carried out in this work. Basis for this investigation is the planetary protection policy that defines the rules to avoid contamination of celestial bodies with organisms from earth, or vice versa. In this work a set of ten isolated bacterial samples was tested for their resistance to different simulated space or mars-like conditions, to find out how big the chance is that some of the isolates survive and to find out if and which strains are more resistant than others. Therefore, ten bacterial strains isolated from one Spacecraft Assembly Facility were dried over night and then exposed to UV-C radiation, vacuum, dessication and UV-C radiation combined with a simulated Martian atmosphere. The titer of the bacterial isolates was determined by plate count and then evaluated. Four isolates and the reference strain survived all test conditions even though with sometimes high inactivation values and five strains did not survive at all or at least only one of the test conditions.