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DEVELOPMENT OF DEFINED MEDIA FOR RAPID PHYSIOLOGICAL PROFILING OF MICROBIAL COMMUNITIES. F.R. Perez,¹ J.L. Garland² and M.S. Roberts². ¹Dept. of Biochemistry, Univ. of Arizona; ²Dynamac Corp., KSC, FL.

Recycling of reusable resources will be vital in planning long-term space missions. Microbial communities, used for recycling within successful bioreactors, will have to be accurately characterized. One easy and rapid method for characterization is using physiological profiling. BiOLOG Inc. produces the MT2 plate designed to conduct such profiling of pure microbial cultures. The goal of this study was to develop an experimental plate more suitable for community-level profiling. Microbial communities were selected for their preference to four amino acids as carbon sources and then plated in the presence of different recipes of growth supporting nutrients (GSN),  two redox dyes as carbon metabolism monitors, and different carbon sources. High concentrations of GSN lead to higher (P<0.05) false response absorbencies (0.70±0.06nm; SD) compared to a low concentration of GSN (0.55 ± 0.05nm) in control wells. There were no significant differences in the level of response between the different recipes used for the GSN comparing Buffered Mineral Salts (BMS) in the absence (1.0±0.01nm) or presence of yeast extract (1.0±0.01nm), casamino acids (0.93±0.01) or both additions (0.90±0.01nm). In comparing redox dyes, tetrazolium violet (1.0±0.01 nm) was more sensitive in experimental wells compared to methylthiazolylidiphenyl (0.45±0.005 nm). MT2 plates (1.1±0.015nm) responded relatively nonspecifically to carbon sources compared to our experimental plates (0.43±0.005 nm). Therefore the MT2 plates might not be functionally relevant for the profiling of microbial communities. These findings show that our experimental plates using BMS alone at a low concentration with tetrazolium violet dye allowed for physiological profiling whereas the MT2 commercial plates were less suitable. 

(Supported by NASA’s SLSTP at KSC and by the NIH through a MARC grant [GM08718-02] at Univ. of Arizona).