Research On Rapid Detection Technology Of Listeria Monocytogenes

Listeria monocytogenes was a common foodborne pathogen, which could cause seriouszoonotic disease. LM, E. coli O157:H7, Salmonella, Staphylococcus aureus were defined asfour major foodborne pathogens by World Health Organization. Rapid detection was animportant means of preventing the LM diseases and public health events. At present, in ourcountry there were3kinds of methods to detect LM, including traditional biologicalcultivation, PCR and automatic identification system. But because there were morecomplicated composition, low target bacterium, and also infecting with multiple pathogens infood testing samples. These detection technology had several problem like long time, high cost,low sensitivity, cumbersome operating, etc. So they could not detect target bacterium in effect.It is necessary to establish a sensitive, accurate, specific, rapid technology for detecting traceLM in food, to ensure that the pathogen could be detected in low concentrations, to improvesensitivity and detection rate, prevent missed and false detection. It was major problem offoodborne pathogen detection, aslo it had important significance and practical value forpreventing and control of LM.7traditional methods and2rapid detection technology were used to detect LM inbacterial suspensions and artificial contaminated food extracts, including traditional biologicalmethods, chromogenic medium method, Bacterium Direct-PCR, DNA Direct-PCR, Bio-PCR,SYBR Green Real time-PCR, TaqMan Real time-PCR and Self-made enzyme conjugatesTAS-ELISA, IC-PCR.This paper compared these methods and defined applied scope. Theresult showed that traditional biological methods had low specificity, negative control growedother bacterium which was difficult to judge by naked eye, so it had to conjunct othertechnologies to improve the experimental accuracy. Chromogenic medium had the advantagesof high specificity, simple operation, but its cost was too high (20yuan/plate) and time was toolong (18-36h), so it was not rapid detection and was suitable for preliminary screening of largesamples in superior laboratory. The cost of Bacteria the Direct-PCR was low (3.5yuan/tube)which without DNA extraction, but it was difficult to exclude impurities bacteria in food.Generally, DNA Direct-PCR was affected by food composition in DNA extraction, thus they only suited to detect pure bacterial suspensions. Bio-PCR had biological enrichment and PCRamplification, it possessed high accuracy and sensitivity, but the high cost (23.5yuan/tube) andlong time caused it suit to recheck research. SYBR Green Real time-PCR without probes, itwas simple operation but low specificity, so this technology had high request on primer andcondition. TaqMan Real time-PCR had high sensitivity (10~1CFU/mL) and good accuracy, butthe same problem was its high costs (23.5yuan/tube) and DNA extracting, so it suit to recheckresearch. Self-made enzyme conjugates TAS-ELISA was simple operation, low cost(3.5yuan/well), short time (6h), and low sensitivity, it was suitable for was suitable forpreliminary screening of large samples. IC-PCR combined immunological techniquesmolecular biology techniques without DNA extracting, using specific antibodies to capture thetrace pathogens in large volume samples for PCR amplification. It could detect5×10~1bacteria/PCR reaction system. Specific experiment and interference experiment indicated thatIC-PCR could detect LM specifically, and no cross-reaction with18strains of commonfoodborne pathogens. The time and cost of detection was less-than7h and7.5yuan/tube.IC-PCR was suitable for detection of trace pathogens in food particularly, and had greaterapplication value. These two rapid rapid detection technology could be researchd Rapid Kit forroutine detection.