Probe technology, also known as nucleic acid hybridization technology, has laid a good foundation for the application of DNA food microbiology techniques and has been widely recognized by relevant academic fields. Probe technology uses the principle of base pairing to DNA as the application basis, detects DNA fragments and RNA fragments with different labeling markers and isotopes, and then determines whether nucleotides contain certain microbial substances. This method can accurately detect pathogenic microorganisms and does not interfere with non-pathogenic microorganisms, which has been widely used in academic circles. It can detect specific forms of RNA and be sensitive to any kind of microorganism.
Although it has obvious advantages, it should be recognized that there are some drawbacks in its application process, such as a certain degree of harm to the operator, complicated operation, relatively high inspection costs, and difficult waste disposal. These problems also limit its application to a certain extent.
PCR technology for food microbiology exam is mainly based on denaturation technology and reconstitution technology. DNA polymerase is used externally and guided by primers and DNTP to achieve millions-fold amplification of the template within a few hours, selectively amplifying DNA, which enables timely and accurate detection results. The application effect in the field of pathogenic food microbiological detection is increasingly obvious. The prerequisite and key of the technology application is to accurately select the target sequence to ensure the accuracy of the amplification results, improve the sensitivity of the detection work, and avoid false positive results.
Fluorescence quantitative PCR technology can be applied on the basis of PCR technology, which can achieve timely quantitative detection results. The main application method is to use fluorescence signals to directly determine the changes during the application of PCR technology, and to automatically amplify the product through dynamic detection of scientific software, thus obtaining accurate detection results. This detection method can accurately detect microorganisms such as lactic acid bacteria, Salmonella, and Shigella.
Food and microbiology plasmid DNA fingerprinting technology is the earliest technology used for typing management and control, and is an analytical technique for the epidemiology of microorganisms. This technology requires the extraction of plasmid DNA for detection and the technical separation of DNA. Different strains of bacteria have differences in the arrangement of plasmid DNA. In the process of this technology application, it is necessary to ensure the effectiveness of the separation work based on different plasmid DNA fingerprinting of different substances, and then realize the reasonable application of the technology.
The reproducibility and resolution of plasmid fingerprinting can be improved by digesting plasmids with restriction endonucleases. The positions and frequencies of endonuclease sites on different plasmids are different, but non-chromosomal material can be easily obtained. According to different plasmid fingerprinting, epidemiological strains of bacteria can be determined to obtain accurate detection results.
The limitation of this technology application is that it cannot be applied to the detection of pathogenic microorganisms without plasmids or with only one or two plasmids in the intermediate strain.
Under the increasingly severe food safety situation, the application of molecular biology in food microbiology techniques is an inevitable trend. Only by continuously combining technology application with practical work, continuously summarizing technical application experience, applying targeted technologies for different detection ranges, improving the efficiency of detection work, and actively learning and applying new technologies, can the level of food quarantine work be guaranteed.