R3 Task D15: Microgravity Effects On Biofilm Stiffness

Biofilm growth has been observed in Soviet/Russian (Salyuts and Mir), American (Skylab), and International (ISS) Space Stations, sometimes jeopardizing key equipment like spacesuits, water recycling units, air filters, radiators, and navigation windows. Several pathogens pose a risk to the health of astronauts during space missions. For example, Staphylococcus aureus is an opportunistic pathogen prevalent on human skin, is prominent in health-care associated infections, and was found aboard several space missions. Like most infections, staph infections are treated with antibiotics. However, space-grown biofilms exhibit increased antibiotic resistance. Therefore, there is a need to understand S. aureus biofilm characteristics and their relationship to antibiotic resistance to help enable safe, long duration, human space missions. Our project goal is to address TASK D15, “Biofilms and the Built Environment,” for which we will provide physical insight into S. aureus biofilms grown in simulated microgravity through stiffness, thickness, and antibiotic resistance measurements. Our hypothesis is that biofilms grown in microgravity produce a densely packed extracellular polymeric substances (EPS) network that results in two measurable outcomes: 1) decreased deformability (increased stiffness) and 2) limited mobility of infiltrants, including antibiotics. Biofilms of Staphylococcus aureus, a potential pathogen that threatens the health of astronauts during space missions, will be grown in simulated microgravity via a high aspect ratio rotating vessel (Synthecon Inc.). Ground control biofilms will also be grown for comparison. We will measure stiffness using atomic force microscopy (AFM) of biofilms grown in simulated microgravity and compare to ground control biofilms. Measures of antibiotic resistance of both types of biofilms will be performed using a BioFilm Ring Test® and/or the Biofilm Eradication Surface Test AssayTM (Innovotech Inc.) in addition to using standard minimum inhibitory concentration (MIC) procedures. This proposal seeks to effectively simulate microgravity to enhance our understanding of fundamental biofilm characteristics. New knowledge gained from this proposal is the relationship between simulated space biofilm stiffness and antibiotic resistance.