Detection of Listeria monocytogenes in Poultry and Livestock Meat by Propidium Monoazide-Hydroxynaphthol Blue-Loop-Mediated Isothermal Amplification Method
DAI Xiaofang, CHEN Qiong, DONG Huaxia, XIANG Chunyan, YU Weiming, LI Juan
Wuhan Institute for Food and Cosmetic Control, Wuhan 430012, China
Abstract：Using propidium monoazide (PMA) treatment and hydroxynaphthol blue (HNB) staining combined with loopmediated isothermal amplification, a rapid and visual detection method (PMA-HNB-LAMP) for Listeria monocytogenes was established in this study. The optimization of experimental parameters showed that a final PMA concentration of 5.0 μg/mL, incubation time of 15 min and exposure time of 15 min could restrain DNA amplification of 105 CFU/mL dead cells but not of live cells. A final HNB concentration of 210 μmol/L could give results visible to the naked eyes. The sensitivity of the PMAHNB-LAMP method was 2.4 × 102 CFU/mL for pure bacterial culture. The detection limit for artificially contaminated meat was 2.3 × 104 CFU/mL. Using the national standard method, PMA-HNB-LAMP and HNB-LAMP, the detection rates of L. monocytogenes in 20 meat products available on the market were 5%, 10% and 20%, respectively. PMA-HNB-LAMP is superior to traditional LAMP in avoiding false-positive results to a certain extent, and it has the advantages of simple operation and strong visibility.
2020, Vol. 34 
