title: Cold plasma technology: bactericidal effects on Geobacillus stearothermophilus and Bacillus cereus microorganisms.
abstract: BACKGROUND
  Cold plasma, also known as Low Temperature Atmospheric Pressure Plasma (LTAPP) is a novel technology consisting of neutral and charged particles, including free radicals, which can be used to destroy or inactivate microorganisms. Research has been conducted regarding the effect of cold plasma on gram-positive bacteria; however, there is limited research regarding its ability to inactivate the spore-formers Geobacillus stearothermophilus and Bacillus cereus.
  
  
  OBJECTIVE
  The purpose of this study was to determine if cold plasma inactivates G. stearothermophilus and B. cereus vegetative cells and spores.
  
  
  METHODS
  Nine hundred eighty-one samples were included in this study (762 experimental and 219 controls). Experimental samples were exposed indirectly or directly to cold plasma, before plating and incubating for 16 hours. Control samples were not exposed to cold plasma. The percentage-kill and cell number reductions were calculated from Colony Forming Units (CFU). Data were statistically analyzed at the .05 level using one-way ANOVA, Kruskal Wallis and Tukey's tests.
  
  
  RESULTS
  There was a statistically significant difference in the inactivation of G. stearothermophilus vegetative cells receiving indirect and direct exposure (p=0.0001 and p=0.0013, respectively), as well as for B. cereus vegetative cells and spores (p=0.0001 for direct and indirect). There was no statistically significant difference in the inactivation of G. stearothermophilus spores receiving indirect exposure (p=0.7208) or direct exposure (p=0.0835).
  
  
  CONCLUSIONS
  Results demonstrate that cold plasma exposure effectively kills G. stearothermophilus vegetative cells and B. cereus vegetative cells and spores; however, G. stearothermophilus spores were not significantly inactivated.
authors.affiliation: Johnson & Johnson Consumer and Personal Products Worldwide, Division of Johnson & Johnson Consumer Companies, Morris Plains, New Jersey, USA.
authors.forename: Angela D
authors.initials: AD
authors.lastname: Morris
authors.forename: Gayle B
authors.initials: GB
authors.lastname: McCombs
authors.forename: Tamer
authors.initials: T
authors.lastname: Akan
authors.forename: Wayne
authors.initials: W
authors.lastname: Hynes
authors.forename: Mounir
authors.initials: M
authors.lastname: Laroussi
authors.forename: Susan L
authors.initials: SL
authors.lastname: Tolle
mesh_terms: D001274:Atmospheric Pressure; D001409:Bacillus cereus / Q000254:growth & development*; D003080:Cold Temperature; D015169:Colony Count, Microbial; D005609:Free Radicals; D001411:Geobacillus stearothermophilus / Q000254:growth & development*; D050296:Microbial Viability; D013170:Spores / Q000254:growth & development; D013242:Sterilization / Q000379:methods*
chemical_list: D005609:Free Radicals