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Passive Observatories for Experimental Microbial Systems- Verification of the Spaceflight Experiment   G. Miller

Passive Observatories for Experimental Microbial Systems (POEMS) is a flight experiment to the International Space Station for investigation of bacterial evolution in a microgravity setting. The POEMS flight equipment consists of the OptiCell™, a small sterile growth chamber sealed between optically clear gas-permeable growth surfaces, housed within a BRIC (Biological Research in a Canister). Each BRIC-Opti canister provides mechanical support for replicate OptiCell™ chambers (shown in Figures 1 and 2), a captured volume of atmosphere for microbial metabolism, and autonomous temperature data logging during the mission. A set of 4 OptiCells™ filled with a growth medium and inoculated with Bacillus subtilis strain 1A2 are placed in each BRIC.  Each OptiCell™ also contains a mixture of nucleic acids that strain 1A2 will have the capability to bind, take-up and recombine in microgravity. Five Opti-BRICs will be in microgravity for eleven days on the shuttle, while five others will remain in space for a progression of one to six months.  The experiment is designed to determine how the bacteria will grow and evolve in the space environment.  This project describes the rate of growth of Bacillus subtilis strain 1A2 in the OptiCell™ growth chamber in response to two key parameters of growth: (1) available energy, and (2) initial inoculum density.  The growth rate of Bacillus  subtilis was investigated in both a liquid growth environment and the semi-solid Opti-Cell chambers across multiple concentrations of a simple carbon source, glucose, and a 4-fold variation in cell density.