The Development Of Field Detection System For Foodborne Pathogenic Bacteria

In recent years,food safety incidents happened frequently and this problem has raised concerns about food safety.The reasons that food safety incidents happen so frequently could be roughly divided into four categories: extensive use of chemical and biological reagents in the production of unprocessed foods,illegal behaviors in the processing of foods,improper food market regulation,safety detection of food microorganism technology and detection system is imperfect.For preventing the food with germs from going into food processing and accessing to markets,a foodborne pathogenic bacteria detection system that is used for field detection is urgently needed,which has the characteristics of high efficiency,sensitiveness and accuracy.According to this problem,the article designed a foodborne pathogenic bacteria field detection system based on magnetic beads adsorption method,isothermal amplification technique and laser measuring technology.The detection system has nucleic acid extraction device and nucleic acid detection device.The lysis and elution of the original bacteria colony take place in the nucleic acid extraction device and then we get the nucleic acid of the pathogenic bacteria;the nucleic acid amplification happens under the constant temperature environment of the detection device.The phosphate ions are generated through the process of nucleic acid amplification and then the ions are combined with Magnesium ions in the buffer to Generate the magnesium pyrophosphate precipitate.Detection device can show the situation of the nucleic acid amplification based on detecting the precipitate concentration and map the nucleic acid amplification curve.The main contents of this article are as follows:(1)The article analyzed the principle of the nucleic acid extraction device and nucleic acid detection device.According to the functions,the two devices are divided into the following five parts: power supply unit,constant temperature unit,man-machine interaction unit,detection unit and communication unit.(2)According to the performance index and function requirement of the nucleic acid extraction device and nucleic acid detection device,the article carried out the overall design of the detection system,including the hardware design and software design of each function unit.The mathematical model of constant temperature unit has been established and the temperature control of the system based on the sliding mode variable structure control algorithm has been realized.(3)The article completed the hardware manufacturing and the software writing of the nucleic acid extraction device and the nucleic acid detection device and made the detection system work well with debugging.It achieved the required precision of temperature control of the constant temperature unit.An experiment about nucleic acid extraction,electrophoresis and detection was conducted.The experimental result shows the foodborne pathogenic bacteria detection system is feasible and has channel consistency.It is observed that the foodborne pathogenic bacteria detection system can go on nucleic acid extraction,nucleic acid amplification and nucleic acid detection and has the advantages of simply operation,high sensitivity,high accuracy,detection channel consistency and high precision for temperature control.