MICROBIAL (BACTERIA AND FUNGI) BEHAVIOR HAS BEEN OBSERVED TO CHANGE IN MICROGRAVITY: ENHANCED BACTERIAL GROWTH IMPROVED CELL AGGREGATION INCREASED VIRULENCE AND REDUCED SUSCEPTIBILITY TO ANTIBIOTICS HAVE BEEN REPORTED ON SPACEFLIGHT EXPERIMENTS. HOWEVER THESE PARAMETERS HAVE NOT BEEN SYSTEMATICALLY ASSESSED AND EVEN LESS SO AT PARTIAL GRAVITIES: 1/6 (LUNAR) AND 1/3 G (MARS). THIS PROJECT AIMS TO CHARACTERIZE CHANGES ON CELL GROWTH DYNAMICS AND CELL AGGREGATION AS A FUNCTION OF THESE GRAVITATIONAL REGIMES (SIMULATED MICRO- 1/6 AND 1/3 G). THIS WILL BE COMPLEMENTED BY GENE EXPRESSION ANALYSES FOCUSED ON THE DRUG-RESISTANCE-ASSOCIATED GENES (RESISTOME) AS WELL AS THOSE RESPONSIBLE FOR BACTERIAL VIRULENCE. THIS SYSTEMATIC MICROBIAL STUDY WILL INCLUDE TEN COMMENSAL OPPORTUNISTIC AND PATHOGENIC BACTERIAL AND FUNGAL STRAINS (OF ESCHERICHIA COLI PSEUDOMONAS AERUGINOSA METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) CANDIDA ALBICANS BACILLUS CEREUS STAPHYLOCOCCUS HAEMOLYTICUS SALMONELLA TYPHIMURIUM AND SHEWANELLA ONEIDENSIS). THIS STUDY HAS A SECOND COMPONENT THAT FOCUSES ON DETERMINING IF THERE ARE CHANGES ON THE CONCENTRATIONS OF DRUGS NEEDED TO INHIBIT MICROBIAL GROWTH AT DIFFERENT GRAVITATIONAL REGIMES LIKE THE ONES EXPECTED TO BE EXPERIENCED DURING DEEP SPACE MISSIONS THE MOON AND MARS. FOR THIS STUDY FOUR DIFFERENT ANTIMICROBIALS (EACH REPRESENTING DISTINCT MECHANISMS OF ACTION) ARE PLANNED TO BE USED: GENTAMICIN SULFATE (AMINOGLYCOSIDE CLASS) WHICH HAS BEEN USED FOR THREE DIFFERENT SPACE-BASED EXPERIMENTS; CIPROFLOXACIN (FLUOROQUINOLONE CLASS) THE MOST COMMONLY PRESCRIBED DRUG FOR URINARY TRACT INFECTIONS (UTI); CEFTOLOZANE/TAZOBACTAM (-LACTAM/-LACTAM COMBINATION ANTIBIOTIC USED ON DRUG-RESISTANT INFECTIONS); AND FLUCONAZOLE (AN AZOLE-CLASS ANTIFUNGAL). THE USE OF SPACEFLIGHT HARDWARE INCLINED CLINOSTATS TO SIMULATE PARTIAL- AND MICRO-GRAVITY AND HUMAN MICROBIOME-ASSOCIATED BACTERIAL AND FUNGAL MODELS WILL ENABLE THIS PROJECT TO ADDRESS RISKS AND GAPS OF NASA#S HUMAN RESEARCH ROADMAP AS WELL AS TO EXPAND OUR UNDERSTANDING OF FUNDAMENTAL CELLULAR AND MOLECULAR MECHANISMS BEHIND MICROBIAL RESPONSES TO CHANGES IN GRAVITY. KNOWLEDGE PRODUCED FROM THIS PROJECT MAY HELP US BETTER PREPARE FOR HUMAN SPACE EXPLORATION OF OTHER CELESTIAL BODIES.