Development of an Inexpensive 3D Clinostat and Comparison with Other Microgravity Simulators using Mycobacterium marinum

M. marinum is a fish pathogen that usually only infects human skin, but it is genetically related to Mycobacterium tuberculosis and Mycobacterium avium and has similar pathogenic mechanisms to these human pathogens. M. marinum and M. avium have been found in biofilms in water distribution systems and showerheads. Therefore, M. marinum is a biosafety level 2 model organism for biofilm-forming pathogenic mycobacteria. M. marinum prefer to form biofilms on hydrophobic surfaces and hydrophobic materials are used on the ISS, an example is silicone. In this study we wanted to examine the transcriptome changes of M. marinum exposed to simulated microgravity in biofilm-promoting medium. M. marinum expressing red fluorescent protein were grown in biofilm-promoting medium in flaskettes containing a piece of PDMS membrane attached to the slide. After filling the flaskettes, cultures were shipped to Kennedy Space station overnight. The flaskettes were attached to the RPM 2.0, or a lab-designed 3D clinostat which were positioned in the same incubator. For the normal gravity control, the flaskette was positioned on the shelf next to the microgravity simulators. After 4 days at 31 degrees C, the bacteria in suspension were used to prepare RNA and RNA-seq was performed to examine gene expression changes.