Microbiological Analysis of the Cloth Bundle Exposed on the External Surface of the International Space Station Over 8 Years

As a part of the space experiment TEST, the cloth bundle was placed on the external surface of the International Space Station (ISS) and returned to Earth after 8 years of exposure to the open space. Microbiological investigation of the cloth resulted in the detection of viable yeasts. Analysis of nucleotide sequences of the rDNA ITS region established that the yeasts belonged to Rhodotorula mucilaginosa. Microsatellite DNA profiling evidenced likeness of the strain isolated from the ISS interior in 2007 and the strain that contaminated the cloth bundle. Physiological testing also revealed significant similarities and some differences of the strain found on the cloth and the cultured yeast strain previously detected in the ISS interior. This investigation demonstrated that the fungal strains recovered from either the ISS interior or from the cloth exposed to outer space had changed sensitivity to antifungal drugs clotrimazole and ketoconazole depending on the number of passages.

Automated summary

Microbiological investigation of the cloth exposed on the International Space Station (ISS) for 8 years revealed viable Rhodotorula mucilaginosa yeasts. These yeasts showed similarities to strains isolated from the ISS interior, and physiological testing indicated some differences between the cloth strain and the cultured yeast strain previously detected in the ISS interior. The investigation also demonstrated the changing sensitivity of fungal strains to antifungal drugs depending on the number of passages.