Primary data analysis was, however, undertaken, cosmonaut samples were cultured, and
DeoxyriboNucleic Acid (DNA)-analysis performed. The swab samples of the ISS were analyzed
by conventional culturing and by DNA analysis methods. Culturing showed that some of the
sites were colonized with bacteria, yeasts, and fungi. However, the actual number of microbes
present could be higher than was found, as storage and transport issues may have resulted in
possible death of part of the microbes. The DNA methods were far less hampered by cell death
and enabled very accurate samples analysis. One method, quantitative real-time Polymerase
Chain Reaction (PCR), showed that surfaces were colonized with human bacteria, such as
staphylococci, in some samples in relatively high numbers. This was in concordance with the
culture results although the culturing numbers were a few orders of magnitude lower. Another
method, fluorescence in situ hybridization (FISH method), showed a similar picture of high
numbers of bacteria, human bacteria, yeasts, and fungi.
The results showed that the microbial contamination of the ISS can be monitored with these
methods and so optimizes the hygiene and health status. Both DNA methods are robust, can be
automated, and have a potential to be used in space. In addition, the analysis of the bacteria in
the specimen case showed no adhesion adaptation following exposure to space conditions for
ten days.
PUBLICATION(S)
Van Tongeren SP, Degener JE, Harmsen HJ. Comparison of three rapid and easy bacterial DNA
extraction methods for use with quantitative real-time PCR. European Journal of Clinical
Microbiology & Infectious Diseases. 2011 February 11; 30(9): 1053-1061. DOI: 10.1007/s10096-
011-1191-4.
This investigation is complete; however, additional results are pending publication.