TABLE 1.
Comparison of the current NASA standard procedure for the detection of contamination on spacecraft and alternative methods using nylon-flocked swabs
| Parameter | Value for: |
Purpose of modification | ||
|---|---|---|---|---|
| NASA standard | Protocol A | Protocol B | ||
| Swab | Cotton swab | Nylon-flocked swab | Nylon-flocked swab | Cotton swab causes residues on surfaces and might inhibit/contaminate molecular analyses |
| Storage solution | Water | PBST | Water | For the detection of vegetative cells, PBST was tested as an alternative |
| Vol (ml) | 10.0 | 2.5 | 2.5 | The volume was decreased to improve handling and reduce risk of losses |
| Extractiona | Sonication and vortexing | Vortexing | Sonication and vortexing | Vortexing is preferred as a sole extraction method for vegetative cells |
| Medium | TSA | R2A | R2A | R2A is more suitable for the cultivation of microbes adapted to low organic concentrations |
| Plating technique | Pour plating | Spread plating | Spread plating | Spread plating facilitates on-site contamination control |
a
Vortexing, 5 to 6 s; sonication, 120 s.