Bacterial and Fungal Communities in BPS Chambers and Root Modules 2003-01-2528

The PESTO (Photosynthetic Experiment System Testing and Operation) experiment flew in the Biomass Production System (BPS) to International Space Station (ISS) on STS-110 (Atlantis) April 8, 2002, and returned on STS-111 (Endeavour) June 19, 2002, after 73 days in space. The ground control was conducted on a two-week delay at Kennedy Space Center in a BPS unit under environmental conditions comparable to ISS. Wheat (Triticum aestivum cv Apogee) and Brassica rapa cv Astroplant were independently grown in root modules for multiple grow-outs. On-orbit harvests, root modules exchanges and primings, seeds imbibitions, and gas and water samplings occurred at periodic intervals; all were replicated in ground controls. Many operations required crew handling and open access to individual chambers, allowing the exchange of microorganisms between the crew environment and the BPS modules. Upon landing, BPS surfaces, containment bags, root modules, and plant material were swabbed for recovery of microbes. Water samples were collected from BPS nutrient delivery and humidity control systems (HCS), root modules, and wastewater bags. Swabs and liquid samples were plated onto selective media; microbial and fungal colonies were identified to the species level by metabolic profiling when possible. Differences in bacterial and fungal species and the number of species identified were detected between the flight and ground controls.