Election of Salmonella Quality Control Strains for Testing According to GB 4789.28 Culture Media and Reagents for Food Microbiological Examination
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Abstract:
The quality of culture media for Salmonella typhimurium was evaluated according to the testing requirements of “GB 4789.28-2013 National Food Safety Standard Food Microbiological Examination - Quality requirements of culture media and reagents” (GB 4789.28-2013). One strain of S. typhimurium equivalent to the ATCC14028 standard strain in GB 4789.28-2013 was selected from the microbial strain bank of China for the evaluation. . As well, seven S. typhimurium from different sources were used by 15 validation laboratories at various institutions to verify different brands of medium according to the GB 4789.28-2013 protocol. The strain with the highest growth rate, selectivity, and consistency with ATCC41028 was selected as the standard equivalent quality control strain. To ensure repeatability and consistency of results, the same brands and batches of media were used for verification in all experiments, and each strain was verified by at least five labs. Growth rate and selectivity results indicated that ATCC41028 grew well on all brands of media. CMCC(B)50976 was most consistent with ATCC41028, while CMCC(B)50976 was the most difficult to culture or isolate. The results of medium validation varied using different brands, personnel, and laboratory environments. The working group selected S. typhimurium strain CMCC(B)50976 as the quality control strain of GB 4789.28, which was equivalent to ATCC14028. The new strain was more representative and reduced the biological risk during transportation of ATCC14028.
