title: Effects of steam autoclave treatment on Geobacillus stearothermophilus spores.
abstract: OBJECTIVE
  To determine the mechanism of autoclave killing of Geobacillus stearothermophilus spores used in biological indicators (BIs) for steam autoclave sterilization, and rates of loss of spore viability and a spore enzyme used in BIs.
  
  
  RESULTS
  Spore viability, dipicolinic acid (DPA) release, nucleic acid staining, α-glucosidase activity, protein structure and mutagenesis were measured during autoclaving of G. stearothermophilus spores. Loss of DPA and increases in spore core nucleic acid staining were slower than loss of spore viability. Spore core α-glucosidase was also lost more slowly than spore viability, although soluble α-glucosidase in spore preparations was lost more rapidly. However, spores exposed to an effective autoclave sterilization lost all viability and α-glucosidase activity. Apparently killed autoclaved spores were not recovered by artificial germination in supportive media, much spore protein was denatured during autoclaving, and partially killed autoclave-treated spore preparations did not acquire mutations.
  
  
  CONCLUSIONS
  These results indicate that autoclave-killed spores cannot be revived, spore killing by autoclaving is likely by protein damage, and spore core α-glucosidase activity is lost more slowly than spore viability.
  
  
  CONCLUSIONS
  This work provides insight into the mechanism of autoclave killing of spores of an organism used in BIs, and that a spore enzyme in a BI is more stable to autoclaving than spore viability.
authors.affiliation: Departamento de Ingenieria Quimica, Alimentos y Ambiental. Universidad de las Americas, Puebla, Mexico.|Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: L C
authors.initials: LC
authors.lastname: Huesca-Espitia
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: M
authors.initials: M
authors.lastname: Suvira
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: K
authors.initials: K
authors.lastname: Rosenbeck
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA.
authors.forename: G
authors.initials: G
authors.lastname: Korza
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 Physics, East Carolina University, Greenville, NC, USA.
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Physics, East Carolina University, Greenville, NC, USA.
authors.forename: S
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Physics, East Carolina University, Greenville, NC, USA.
authors.forename: Y-Q
authors.initials: YQ
authors.lastname: Li
authors.affiliation: Department of Molecular Biology and Biophysics, UConn Health, Farmington, CT, USA. setlow@nso2.uchc.edu.
authors.forename: P
authors.initials: P
authors.lastname: Setlow
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D001411:Geobacillus stearothermophilus / Q000737:chemistry / Q000235:genetics; D009154:Mutation; D010848:Picolinic Acids / Q000032:analysis; D013171:Spores, Bacterial / Q000737:chemistry; D013227:Steam; D013242:Sterilization
chemical_list: D001426:Bacterial Proteins; D010848:Picolinic Acids; D013227:Steam; C004860:dipicolinic acid
keywords: bacterial spores; enzymes; indicators; sterilization; thermal processes