THE FOCUS OF THIS PROPOSAL IS ON THE CREATION OF A SIMULATION TECHNIQUE TO PREDICT THE INTERACTION BETWEEN FLUID FLOW AND ITS AFFECTS ON BACTERIAL GROWTH, SPECIFICALLY INVESTIGATING THE USE OF GROUND-BASED ANALOGS FOR BIOREACTORS. RECENT INVESTIGATIONS HAVE REPORTED INCREASED UTILIZATION OF GROUND-BASED SIMULATORS THAT USE ROTATING REACTORS TO PLACE BACTERIA IN A STATE OF FREE FALL THAT IS SIMILAR TO CONDITIONS ON THE SPACE STATION. HOWEVER, THE EFFECTS OF FLUID FLOW, INCLUDING CONVECTION AND SEDIMENTATION, ON THE GENOMICS DURING BACTERIAL GROWTH ARE UNKNOWN. ..INTELLECTUAL MERIT: IN THIS PROPOSAL, THE PI WILL INVESTIGATE AN INNOVATIVE NUMERICAL PLATFORM THAT USES STOKESIAN DYNAMICS TO MODEL BACTERIA IN A ROTATING WALL VESSEL (RWV). SUSPENSIONS OF BACTERIA WILL BE SIMULATED UNDER VARIOUS OPERATING CONDITIONS TO IDENTIFY DOMINATE CHARACTERISTICS THE GOVERN SUSPENSION MECHANICS. SUCCESSFUL COMPLETION OF THIS PROJECT WILL DEFINE THE NECESSARY CONDITIONS TO KEEP A SUSPENSION OF BACTERIA INDEFINITELY SUSPENDED. TO OVERCOME GEOMETRIC LIMITATIONS THAT ARE OFTEN ENCOUNTERED IN PREVIOUS INVESTIGATIONS, ASSEMBLIES OF SPHERES WILL BE UTILIZED TO REPRESENT THE ASPHERICAL NATURE OF THE BACTERIA. THESE SIMULATIONS WILL ATTEMPT TO MATCH ONGOING PRECISION EXPERIMENTS THAT ARE BEING FUNDED THROUGH NASA EPSCOR. THE INVESTIGATION WILL PROVIDE DETAILED INSIGHTS INTO THE SUSPENSION MECHANICS OF THE BACTERIA DURING THEIR GROWTH IN THE MEDIA, WHILE DIRECTING OPTIMAL OPERATION OF THE RWV. ..BROADER IMPACTS: BEYOND IDENTIFYING THE NECESSARY OPERATING CONDITIONS FOR THE RWV TO ENSURE INDEFINITE SUSPENSION AND ADEQUATE ACCESS TO NUTRITION FOR THE BACTERIA IN A RWV, SUCCESSFUL COMPLETION OF THIS PROJECT WOULD PROVIDE FUNDAMENTAL INSIGHT INTO THE SUSPENSION MECHANICS OF BACTERIA IN GROUND-BASED MICROGRAVITY ANALOGS. THIS INFORMATION, COUPLED WITH MODELS TO ACCOUNT FOR MASS TRANSFER, COULD LEAD TO DIRECTED ENGINEERING OF GROWTH CONDITIONS, INCLUDING SUITABLE NUTRIENT ACCESS AND CONSISTENT MECHANICAL STRESS CONDITIONS. FURTHER, THIS INFORMATION WILL DIRECT NEW STUDIES TO COMPARE GROUND-BASED ANALOGS TO IN-SPACE BIOREACTORS AND THE DIFFERENCES THAT THESE ENVIRONMENTS HAVE ON MICROBIAL GROWTH. .