Bacillus subtilis Spore Resistance towards Low Pressure Plasma Sterilization

1. Non-thermal Plasmas for Sterilization 1.1 Motivation for Search of Alternative Sterilization Methods Microbial contamination on surfaces is a recurring problem within health, pharmaceutical and food industry sectors (Abreu et al., 2013, Rutala and Weber, 2013). Surface sterilization is a crucial step to ensure sterility of food processing equipment, minimize spread of pathogens and prevent the transmission of nosocomial infections (Williams et al., 2009). Common sterilization procedures that are widely used for microbial inactivation include heat treatment (dry and moist heat), chemical disinfection with solutions or gases (H2O2, ethylene oxide), filtration, and exposure to ionizing radiation (reviewed in Rutala and Weber, 2013). While generally effective, most conventional methods suffer from significant drawbacks and restrictions. Currently employed procedures can introduce considerable damage to the treated material due to the exposure to elevated temperatures or aggressive chemicals and often pose a risk to the operator, rendering these methods suboptimal in many applications (Yardimci and Setlow, 2010). These limitations have motivated the search for alternative sterilization methods. Plasma sterilization is a promising alternative to conventional sterilization methods as it offers rapid and efficient microbial inactivation, while being gentle to sensitive and heatlabile materials and very safe to the operating staff. Over the last decade, the application of non-thermal plasmas has gained wide attention in biomedical and nutritional research, as well as in space-flight applications (De Geyter and Morent, 2012, Shimizu et al., 2014; Lerouge, 2000)