title: Identification of heat stable protease of Klebsiella oxytoca isolated from raw milk.
abstract: OBJECTIVE
  The aim of this study was to identify and characterize heat stable proteinases of psychrotrophic proteolytic bacteria isolated from raw milk.
  
  
  RESULTS
  A strain of Klebsiella oxytoca producing a high proteolytic activity when cultured on milk was isolated. Maximum proteolytic activity was observed at the stationary phase during growth on milk or casein-peptone broth. The bacterium demonstrated the capability to grow at 7 degrees C, classified as psychrotrophic. The crude enzyme showed optimum activity at 37 degrees C, and pH 5.0 and 7.0. The proteinase was very resistant to heat, maintaining 74% of initial activity after incubation at 142 degrees C.
  
  
  CONCLUSIONS
  A heat stable protease of a psychrotrophic strain of K. oxytoca was identified and partially characterized.
  
  
  CONCLUSIONS
  Thermal stable proteases may constitute a serious problem to ultra-high temperature (UHT) processed milk, leading to undesirable physical and sensory alterations.
authors.affiliation: Departamento de Ciência de Alimentos, ICTA, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: E C
authors.initials: EC
authors.lastname: Tondo
authors.forename: F R
authors.initials: FR
authors.lastname: Lakus
authors.forename: F A
authors.initials: FA
authors.lastname: Oliveira
authors.forename: A
authors.initials: A
authors.lastname: Brandelli
mesh_terms: D000818:Animals; D004795:Enzyme Stability; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D041121:Klebsiella oxytoca / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification*; D008892:Milk / Q000382:microbiology*; D010447:Peptide Hydrolases / Q000378:metabolism*; D013696:Temperature
chemical_list: D010447:Peptide Hydrolases