Microbiological Sampling of the Multi-Purpose Logistics Module from Return to Flight Mission ISS LF-1/STS-114

Airborne and surface microbiological sampling was performed on the pressurized Multi-Purpose Logistics Module “Raffaello” (MPLM-6) that serviced the International Space Station (ISS) on NASA Return to Flight mission ISS LF-1/STS-114. In September of 2005, aerosol samples and surface samples were collected from the MPLM at the Kennedy Space Center prior to locker de-stow and module de-integration. Analyses of the culturable bacterial count from selective and non-selective media showed low microbial densities (>100 CFU per sq m) in the MPLM surface samples collected from air filtration ducts and other hardware surfaces. Isolates identified included diverse representatives of the gram-negative and gram-positive bacteria as well as common airborne fungi. Although aerosol bio-burden samples plated onto non-selective media were below detection limit in microbial density (<1 CFU per 500 L), bacterial and fungal populations were detected in surface swab samples. The objective of this study is to characterize the culturable and non-culturable components of the microbial community on the International Space Station and to develop a microbial risk assessment for long duration missions.