食品中单增李斯特菌检验方法的应用研究

Study on test methods of Listeria bacteria in food

目的单增李斯特菌定性检测结合实时荧光PCR、MPN计数法,在食源性致病菌检测中快速进行定性及定量检测。方法用不同浓度的单增李斯特菌的菌悬液污染样品,对细菌培养法和实时荧光PCR法进行比较;分别对当天、冷藏2 d、冷冻6 d的增菌液进行MPN计数法定量检测,比较三种情况下MPN计数的结果。结果细菌培养法和实时荧光PCR法检测,两者结果相符,最低检测限均为1 cfu/g;MPN计数法定量检测,三个时间段检测结果显示,(1)和(2)的结果相符,与(3)的结果有差异。结论实时荧光PCR法和MPN计数法定量检测相结合,既避免了由于样品细菌培养法检测出阳性结果后,定量检测时重新取样而导致的结果差异,又缩短了检验周期,这样不仅减少了工作量,也大大提高了工作效率。

Objective To conduct quantitative detection and qualitative detection of Listeria monocytogenes in food by combina- tion of real - time fluorescence PCR and MPN counting method. Methods Bacterial suspension samples of Listeria monocyto- genes at different concentrations were detected by bacteria culture method and real - time fluorescent PCR method, and the re- sults were compared; Then quantitative detection was done in the enrichment broth by MPN counting method on the first day, 2 -day cold storage, 6 - day frozen storage to compare the detection results of the three kinds of enrichment broth. Results Bacteria culture method and real - time fluorescence PCR method showed consistent detection results, and the detec- tion limits were both 1 cfu/g; By MPN method, the quantitative detection results was consistent between the first day and 2 - day cold storage, but both had difference with that of 6 -day cold storage. Conclusion Real -time fluorescence PCR method combining with MPN counting method has avoided the error due to resampling in quantitative detection after positive results obtained by bacterial culture method, and shorten the test cycle, thus reducing the workload and improving the working efficiency.