title: Sterilization of bacteria, yeast, and bacterial endospores by atmospheric-pressure cold plasma using helium and oxygen.
abstract: Atmospheric-pressure cold plasma (APCP) using helium/oxygen was developed and tested as a suitable sterilization method in a clinical environment. The sterilizing effect of this method is not due to UV light, which is known to be the major sterilization factor of APCP, but instead results from the action of reactive oxygen radicals. Escherichia coli, Staphylococcus aureus, and Saccharomyces cerevisiae deposited on a nitrocellulose filter membrane or Bacillus subtilis spores deposited on polypropylene plates were exposed to helium/oxygen plasma generated with AC input power at 10 kHz, 6 kV. After plasma treatment, nitrocellulose filter membranes were overlaid on fresh solid media and CFUs were counted after incubation overnight. D-values were 18 sec for E. coli, 19 sec for S. aureus, 1 min 55 sec for S. cerevisiae, and 14 min for B. subtilis spores. D-values of bacteria and yeast were dependent on the initial inoculation concentration, while the D-value of B. subtilis spores showed no correlation. When treated cells were observed with a scanning electron microscope, E. coli was more heavily damaged than S. aureus, S. cerevisiae exhibited peeling, and B. subtilis spores exhibited shrunken morphology. Results showed that APCP using helium/oxygen has many advantages as a sterilization method, especially in a clinical environment with conditions such as stable temperature, unlimited sample size, and no harmful gas production.
authors.affiliation: Department of Biology, College of Natural Sciences, Seoul Women's University, Seoul 139-774, Republic of Korea.
authors.forename: Kyenam
authors.initials: K
authors.lastname: Lee
authors.forename: Kwang-hyun
authors.initials: KH
authors.lastname: Paek
authors.forename: Won-Tae
authors.initials: WT
authors.lastname: Ju
authors.forename: Yoenhee
authors.initials: Y
authors.lastname: Lee
mesh_terms: D001274:Atmospheric Pressure; D001412:Bacillus subtilis / Q000187:drug effects / Q000502:physiology; D001419:Bacteria / Q000187:drug effects*; D003080:Cold Temperature; D015169:Colony Count, Microbial; D003470:Culture Media; D004926:Escherichia coli / Q000187:drug effects / Q000254:growth & development; D005740:Gases / Q000494:pharmacology; D006371:Helium / Q000494:pharmacology*; D008855:Microscopy, Electron, Scanning; D010100:Oxygen / Q000494:pharmacology*; D012441:Saccharomyces cerevisiae / Q000187:drug effects* / Q000254:growth & development; D013171:Spores, Bacterial / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects / Q000254:growth & development; D013242:Sterilization / Q000379:methods*
chemical_list: D003470:Culture Media; D005740:Gases; D006371:Helium; D010100:Oxygen