PCR detection system for simultaneously detecting multiple food-borne pathogenic bacteria and construction method
A construction method and pathogenic bacteria technology, applied in the field of biomedical detection, can solve the problems of cumbersome and time-consuming detection methods, low accuracy and sensitivity
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Embodiment 1
[0073] The extraction of embodiment 1DNA
[0074] (1) Log in to GenBank and query the target genes of five foodborne pathogens including Staphylococcus aureus, Listeria monocytogenes, Shigella flexneri, Yersinia enterocolitica, and Clostridium difficile in the nucleic acid database the conserved sequence;
[0075] (2) Target the nuc gene of Staphylococcus aureus, the hlyA gene of Listeria monocytogenes, the ipaH gene of Shigella flexneri, the lysP gene of Yersinia enterocolitica and the tpi gene of Clostridium difficile , carrying out the design of specific oligonucleotide primers;
[0076] (3) Submit the designed candidate sequences to GenBank for BLAST comparison, screen out sequences with better specificity, and synthesize oligonucleotide primers respectively;
[0077] (4) Cultivate the standard and clinical sample bacteria of five kinds of bacteria, use the TIANGEN Bacteria Genomic DNA Kit to extract the DNA of all pathogenic bacteria, and use the DNA-containing supernat...
Embodiment 2
[0079] The establishment and optimization of embodiment 2 PCR reaction system
[0080] The embodiment of the present invention carries out following optimization process on the basis of initial detection system, the preparation of the PCR reaction solution of this initial detection system is:
[0081]
[0082] The PCR reaction conditions are as follows:
[0083] Pre-denaturation: 94°C, 5min,
[0084] Denaturation: 94°C, 30s,
[0085] Annealing: T°C, 30s,
[0086] Extension: 72°C, 30s,
[0087] Number of cycles: 30,
[0088] Final extension: 72°C, 7min,
[0089] The temperature T of each bacteria corresponding to the above-mentioned annealing is shown in Table 1 below:
[0090] Table 1 Annealing temperature
[0091]
[0092] The optimization process includes the following steps:
[0093] (1) Single-plex PCR optimization detection system for five bacteria
[0094] Apply the designed and synthesized primers to the above-mentioned initial detection system, and carry...
Embodiment 3
[0154] Sensitivity and specificity detection of embodiment 3 multiplex PCR
[0155] To verify the specificity of the primers, each primer was reacted with five bacterial DNA mixtures. Likewise, DNA from each pathogen was subjected to PCR reactions with a mixture of five primers. The specificity of PCR primers is shown in Table 3. When the primers are specific and the amplified product does not produce non-target bands, it proves that the specificity of PCR amplification is better.
[0156] Table 3 PCR primer specificity
[0157]
[0158] Measure the DNA concentration of all strains using a UV spectrophotometer. DNA was extracted from five bacterial cultures, and each bacterial DNA was diluted 10-fold, then mixed, and subjected to multiplex PCR for sensitivity detection. The detection limits of each genomic DNA in the multiplex PCR were: 228pg for Staphylococcus aureus, 365pg for Listeria monocytogenes, 1.9pg for Shigella flexneri, 223pg for Clostridium difficile, and 22...
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