Q-216. Microbial Community Profiling of Stored Space-Shuttle Food Waste Extracts

M. N. Birmele, J. T. Richards, M. P. Hummerick, R. F. Strayer, M. S. Roberts;
Dynamac Corp., Kennedy Space Center, FL.

Research and development are underway to produce advanced solid waste handling systems for the new generation of NASA spacecraft and surface habitation systems. Space shuttle trash contains uneaten food, food packaging and containers, and various wipes (body, wet, dry, and disinfectant wipes). In previous solid waste studies, a simulated food waste was inoculated with pooled buccal and saliva samples from volunteer donors. However, access to Volume F trash (primarily food wastes and packaging) from a recent U.S. space shuttle mission raised the possibility of deriving a food waste inoculum from a source which more closely approximates the diverse microbial community composition found on spacecraft, but the infrequency of shuttle flights meant inoculum storage would be required. To maintain a consistent inoculum composition throughout future experiments, it was necessary to determine if a freeze-thaw cycle, as part of storage preparation, negatively affected microbial community composition. Selected food waste items from the shuttle trash were sampled, added to a slurry, pooled, and either stored at 4oC (R), slow frozen at -80oC (SS), or fast frozen in an isoproyl alcohol quick-freeze kit at -80oC (FS). After 72 h storage, quadruplicate DNA samples from each treatment were isolated and highly conserved gene regions were amplified with primer sets for bacterial 16S ribosomal DNA (rDNA) and the fungal ribosomal internal transcribed spacer (ITS) gene. The amplicon was then digested with multiple restriction endonucleases that provided a multi-view cross-section of the microbial diversity to illustrate the community structure and then analyzed by Terminal Restriction Fragment Length Polymorphism (T-RFLP). Results showed that the initial freeze-thaw cycle and short storage duration did not indicate a significant statistical difference in community composition between treatments. A large number of other inocula samples have been stored and the desire is to use this authentic space-mission derived inocula in future studies on the fate (survival and growth) of human pathogens from cross-contamination from other space mission solid wastes such as crew feces.