title: Development and validation of stable reference materials for food microbiology using Bacillus cereus and Clostridium perfringens spores.
abstract: OBJECTIVE
  To develop a new type of microbiological Reference Materials (RMs), displaying long-term stability at room temperature. The purpose was to produce and validate two batches of RMs for the enumeration of Bacillus cereus and Clostridium perfringens.
  
  
  RESULTS
  The RMs were based on spores of B. cereus and Cl. perfringens, adsorbed on calcium carbonate pellets. Two batches of 1000 units were manufactured and validated in compliance with ISO guide 35. After verification of their homogeneity, the stability of the 'RM-B. cereus' and 'RM-Cl. perfringens' batches was proven during at least 36 and 9 months, respectively, at room temperature. The validation study was completed by international collaborative trial involving 12 laboratories, allowing the validation of the assigned values.
  
  
  CONCLUSIONS
  The methodology developed in this work enabled to produce easy-to-handle and cost-effective RMs, displaying an unprecedented stability at room temperature, a good homogeneity and a precise and validated assigned value.
  
  
  CONCLUSIONS
  This study revealed new paths for the development of stable microbiological RMs. Overcoming the intrinsic instability of the living cells makes it possible to produce valuable tools for the quality assurance of microbiology laboratories.
authors: Laboratory of Food and Environmental Microbiology, Earth and Life Institute, Université catholique de Louvain, Louvain-La-Neuve, Belgium. marleen.abdelmassih@uclouvain.be
authors: M
authors: M
authors: Abdelmassih
authors: V
authors: V
authors: Planchon
authors: C
authors: C
authors: Anceau
authors: J
authors: J
authors: Mahillon
mesh_terms: D001409:Bacillus cereus / Q000254:growth & development*; D001431:Bacteriological Techniques / Q000379:methods*; D003016:Clostridium perfringens / Q000254:growth & development*; D015169:Colony Count, Microbial; D005516:Food Microbiology / Q000379:methods / Q000592:standards*; D012015:Reference Standards; D013171:Spores, Bacterial / Q000254:growth & development; D013696:Temperature