title: Mechanism of Bacillus subtilis spore inactivation by and resistance to supercritical CO2 plus peracetic acid.
abstract: OBJECTIVE
  Determine how supercritical CO2 (scCO2 ) plus peracetic acid (PAA) inactivates Bacillus subtilis spores, factors important in spore resistance to scCO2 -PAA, and if spores inactivated by scCO2 -PAA are truly dead.
  
  
  RESULTS
  Spores of wild-type B. subtilis and isogenic mutants lacking spore protective proteins were treated with scCO2 -PAA in liquid or dry at 35°C. Wild-type wet spores (aqueous suspension) were more susceptible than dry spores. Treated spores were examined for viability (and were truly dead), dipicolinic acid (DPA), mutations, permeability to nucleic acid stains, germination under different conditions, energy metabolism and outgrowth. ScCO2 -PAA-inactivated spores retained DPA, and survivors had no notable DNA damage. However, DPA was released from inactivated spores at a normally innocuous temperature (85°C), and colony formation from treated spores was salt sensitive. The inactivated spores germinated but did not outgrow, and these germinated spores had altered plasma membrane permeability and defective energy metabolism. Wet or dry coat-defective spores had increased scCO2 -PAA sensitivity, and dry spores but not wet spores lacking DNA protective proteins were more scCO2 -PAA sensitive.
  
  
  CONCLUSIONS
  These findings suggest that scCO2 -PAA inactivates spores by damaging spores' inner membrane. The spore coat provided scCO2 -PAA resistance for both wet and dry spores. DNA protective proteins provided scCO2 -PAA resistance only for dry spores.
  
  
  CONCLUSIONS
  These results provide information on mechanisms of spore inactivation of and resistance to scCO2 -PAA, an agent with increasing use in sterilization applications.
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: B
authors.initials: B
authors.lastname: Setlow
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: G
authors.initials: G
authors.lastname: Korza
authors.affiliation: NovaSterilis Inc., Lansing, NY, USA.
authors.forename: K M S
authors.initials: KM
authors.lastname: Blatt
authors.affiliation: NovaSterilis Inc., Lansing, NY, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Fey
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: P
authors.initials: P
authors.lastname: Setlow
mesh_terms: D001412:Bacillus subtilis / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D002245:Carbon Dioxide / Q000494:pharmacology*; D004249:DNA Damage / Q000187:drug effects; D024881:Drug Resistance, Bacterial; D009154:Mutation / Q000187:drug effects; D010463:Peracetic Acid / Q000494:pharmacology*; D013171:Spores, Bacterial / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development
chemical_list: D002245:Carbon Dioxide; D010463:Peracetic Acid
keywords: inner spore membrane; spore inactivation; spore resistance; spores; supercritical carbon dioxide