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VALIDATION OF METHODS AND MICROBIAL ANALYSIS OF ADVANCED LIFE SUPPORT (ALS) SALAD CROPS.  P.F. Lopez II1 and M. Hummerick2  1North Carolina Agricultural and Technical State University, Greensboro 27411; 2Dynamac Corporation, Kennedy Space Center, 32899.

   The methods for the isolation of Escherichia coli and Staphylococcus aureus in broth cultures and processed edible plant samples (lettuce, onion, and radish) were evaluated and compared. Microbial analysis of chamber-grown salad crops for microbial quality, density, and for the presence of potential human pathogenic bacteria including E. coli and S. aureus were performed. Broth cultures of S. aureus-25923 and E. coli-11303 of the American Type Culture Collection strain were grown and diluted to a turbidity equal to ~1.5x108 cells/mL. Cultures were serially diluted and filtered: S. aureus was plated on 3M Petrifilm Rapid S. aureus Count Plates, and E. coli was plated on 3M Petrifilm coliform/E. coli Count Plates. Live/Dead and acridine orange direct counts were performed on cultures. Lettuce, onion, and radish samples were collected in sterile sample bags and weighed. Each sample was diluted and plated onto Plate Count Agar for isolation of S. aureus and E. coli. Lettuce, onion, and radish samples were inoculated. The detection limit was not affected due to the numbers of bacteria in the plant components after blending.