Research on the quantification method to detect pathogenic bacteria in instant rice noodles by 3-plex droplet digital polymerase chain reaction test
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1.Guangzhou Institute for Food Inspection, Guangdong Guangzhou 511400, China;2.Guangzhou Intellectual Property Protection Center, Guangdong Guangzhou 510010, China;3.ALS Canada Ltd., British Columbia V4A1W9, Canada

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R155

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    Abstract:

    Objective This study aimed to establish a quantitative 3-plex droplet digital polymerase chain reaction (ddPCR) method for simultaneously detecting the copy numbers of SalmonellaBacillus cereus, and Listeria monocytogenes in instant food.Methods Three pairs of primers and probes corresponding to three single-copy-genes were selected as target genes. The genes were the essC gene in Bacillus cereusttrA/ttrC gene in Salmonella, and invasion-associated endopeptidase gene in Listeria monocytogenes. The specificity of the primers and probes were verified by real-time fluorescence quantitative PCR separately. A 3-plex ddPCR method was constructed to detect the copy numbers of three pathogenic bacteria simultaneously.Results The linear ranges were: 25-22 687 copies/20 μL for Salmonella, 19-15 620 copies/20 μL for Bacillus cereus, and 18-23 373 copies/20 μL for Listeria monocytogenes. The three linear correlation coefficients were r≥0.999. relative standard deviation (RSD)≤12% at six concentrations and repeated thrice, indicating favorable repeatability. The minimum detection limits were six copies/20 μL for Salmonella, three copies/20 μL for Bacillus cereus, and seven copies/20 μL for Listeria monocytogenes. When a simulated sample of contaminated rice noodles was detected by 3-plex ddPCR and the plate counting method, the deviation between these two methods was <9%, indicating a good consistency in the results.Conclusion The 3-plex ddPCR method for the simultaneous and quantitative detection of Salmonella, Bacillus cereus, and Listeria monocytogenes in instant food was quicker, more sensitive, and more accurate than the plate-counting method.

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SUN Xueqi, YIN Weilu, JIANG Jiaxi, ZHANG Mingming, LIANG Meidan, ZENG Shanmei, XIAO Jian. Research on the quantification method to detect pathogenic bacteria in instant rice noodles by 3-plex droplet digital polymerase chain reaction test[J].中国食品卫生杂志,2023,35(11):1571-1578.

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History
  • Received:December 02,2022
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  • Online: February 20,2024
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