Zhongguo shipin weisheng zazhi (Aug 2023)

Development of ready-to-use standard strains of Salmonella typhimurium TA97, TA98, TA100, and TA102

  • YU Wen,
  • AN Lin,
  • CHEN Yiwen,
  • REN Xiu,
  • LI Jingyun,
  • CUI Shenghui

DOI
https://doi.org/10.13590/j.cjfh.2023.08.002
Journal volume & issue
Vol. 35, no. 8
pp. 1140 – 1145

Abstract

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ObjectiveThis study aimed to develop ready-to-use standard strains of Salmonella typhimurium （S. typhimurium） TA97， TA98， TA100， and TA102 for mutagenicity testing.MethodsFreeze-dried strains of S. typhimurium TA97， TA98， TA100， and TA102 at both high and low concentrations were quantified. The spontaneous reversion rate of the freeze-dried strains after 3， 5， 7， and 18 h was measured. Homogeneity， storage and transportation stability， spontaneous revertant frequency， and mutagenic agent mutation rate of the ready-to-use standard strains were evaluated following the CNAS-GL003 2018 “Guidelines for the Evaluation of Homogeneity and Stability of Proficiency Testing Samples” and GB 15193.4—2014 “National Food Safety Standard - Bacterial Reverse Mutation Test.” Standard deviations of spontaneous revertant frequency and mutagenic agent mutation rate test results between 20 ready-to-use standard strains and fresh strains were compared.ResultsHigh-concentration lyophilized samples had concentrations ranging from 107-108 CFU/sample， while low-concentration samples had concentrations ranging from 105-106 CFU/sample. The spontaneous reversion rate results after 18 h of incubation met the requirements of GB 15193.4—2014. Homogeneity results for the four ready-to-use standard strains showed F-values of 1.12， 1.05， 1.68， and 1.38， with F < F0.05 （19，20）， meeting CNAS-GL003 requirements. The detection results for the four freeze-dried strains stored at 25 ℃ for 5 d， 4 ℃ for 14 d， and -20 ℃ for 6 months met storage and transportation stability requirements. The standard deviation of spontaneous revertant frequency in the 20 ready-to-use freeze-dried standard strains was smaller than that of fresh strains.ConclusionThe ready-to-use standard strains developed in this study exhibit excellent homogeneity， storage， and transportation stability. Moreover， the stability of spontaneous revertant frequency in the ready-to-use freeze-dried standard strains surpasses that of fresh strains.

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