(815d) Biofilm Formation During Spaceflight: Insights From Mathematical Modeling of Growth in the Microgravity Environment

There is an urgent need to understand the effects of microgravity on microbial biofilm formation and the factors that affect the potential for biofilm-related infections, biofouling and biocorrosion during spaceflight. Microbial growth and physiology have been studied extensively in spaceflight and simulated microgravity and many changes have been observed. We have recently conducted two sets of spaceflight experiments (Micro-2 and Micro-2A) and shown the biofilm formation by two opportunistic pathogens, Pseudomonas aeruginosa and Staphylococcus aureus, is affected by spaceflight. However, while P. aeruginosa biofilm formation was found to increase, S. aureus biofilm formation was found to decrease during spaceflight compared to ground controls conducted on Earth. In order to understand this descrepancy, as well as our observation that the differences can be modulated by nutrient availability, we have constructed a mathematical model of microbial growth and biofim formation during sapceflight. In addition to gravity, which causes the cells to settle in normal gravity or is omitted in microgravity, the model includes Monod type equations for growth of biofilm and planktonic fractions, a Langmuir isotherm-type binding constant that captures the cell’s affinity for a particular surface. Through sensitivity analysis we have identified several key parameters that can affect biofilm formation, either positively or negatively, in microgravity.