title: Extracellular protectants produced by Clostridium perfringens cells at elevated temperatures.
abstract: OBJECTIVE
  The mechanisms of adaptation of Clostridium perfringens to high temperatures are not well understood. In this work, the involvement of extracellular compounds in protection to heat was determined.
  
  
  RESULTS
  Cells were grown in fluid thioglycollate medium or chicken broth. When mid-log phase was reached, they were heat-shocked at 50 degrees C for 30 min. Then cultures were centrifuged and supernatants were transferred to nonshocked cells. Heat tolerance of these cells was performed at 55 degrees C. Viable cells were determined. In some cases, supernatants were heated at 65 degrees C or 100 degrees C or treated with trypsin. Supernatants were fractionated and PAGE was made of fractions showing heat-protective activity. When C. perfringens was exposed to a heat shock at 50 degrees C, extracellular factors were found in the culture supernatant that provided protection to cells not exposed to a heat shock. The extracellular factors were sensitive to heat and trypsin treatment suggesting a protein component. SDS-PAGE analysis of supernatant fractions from heat-treated cells revealed two induced proteins (56 and 125 kDa) that could be involved in heat tolerance.
  
  
  CONCLUSIONS
  In this work, the presence and thermoprotective activity of extracellular factors produced by C. perfringens under a heat shock was demonstrated.
  
  
  CONCLUSIONS
  The detection of thermoprotective extracellular factors of C. perfringens will aid in our understanding of the physiology of survival of C. perfringens in foods.
authors.affiliation: Departamento de Microbiología e Inmunología, Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, San Nicolás, Nuevo León, México.
authors.forename: N
authors.initials: N
authors.lastname: Heredia
authors.forename: P
authors.initials: P
authors.lastname: Ybarra
authors.forename: C
authors.initials: C
authors.lastname: Hernández
authors.forename: S
authors.initials: S
authors.lastname: García
mesh_terms: D000222:Adaptation, Physiological; D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000737:chemistry; D003016:Clostridium perfringens / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D006358:Hot Temperature; D050296:Microbial Viability; D008970:Molecular Weight
chemical_list: D001426:Bacterial Proteins