title: Effect of feed gas composition of gas discharge plasmas on Bacillus pumilus spore mortality.
abstract: OBJECTIVE
  To investigate the effect of gas composition on the sensitivity of Bacillus pumilus spores to gas plasmas.
  
  
  RESULTS
  Inert gas plasmas, oxygen-based plasmas and various moisturized air plasmas were used to inactivate B. pumilus spores in low gas pressure of 50 Pa. Although the treatment temperature did not exceed 55 degrees C when exciting these plasmas, spore survival varied widely depending on the composition of the gas feed. Higher spore mortality was acquired by inert gases of low molecular weight except for helium. The highest spore mortality (4.54log reduction) was obtained when air with a 0.05 molar fraction of water vapour was used as the plasma carrier gas.
  
  
  CONCLUSIONS
  Water molecules in the plasma carrier gas play a significant role in inactivation of B. pumilus spores.
  
  
  CONCLUSIONS
  This strong inactivation may occur through hydroxyl free radicals generated from the moisturized air plasma.
authors.affiliation: Faculty of Agriculture, Laboratory of Food Process Engineering, Kyushu University, Fukuoka, Japan.
authors.forename: D
authors.initials: D
authors.lastname: Purevdorj
authors.forename: N
authors.initials: N
authors.lastname: Igura
authors.forename: O
authors.initials: O
authors.lastname: Ariyada
authors.forename: I
authors.initials: I
authors.lastname: Hayakawa
mesh_terms: D000391:Air Microbiology; D001128:Argon / Q000737:chemistry / Q000494:pharmacology; D001407:Bacillus / Q000187:drug effects* / Q000254:growth & development; D005740:Gases / Q000737:chemistry / Q000494:pharmacology*; D006358:Hot Temperature; D005741:Noble Gases / Q000737:chemistry / Q000494:pharmacology; D010100:Oxygen / Q000737:chemistry / Q000494:pharmacology; D013171:Spores, Bacterial / Q000187:drug effects / Q000254:growth & development; D013242:Sterilization; D016019:Survival Analysis
chemical_list: D005740:Gases; D005741:Noble Gases; D001128:Argon; D010100:Oxygen