Method for separating staphylococcus aureus (SA)

Abstract

The invention discloses a method for enriching and separating staphylococcus aureus (SA), provides a good basis to the subsequent research on a target bacterium, and relates to the technical field of biology. The method comprises the following steps: performing covalent coupling on a dendrimer and an antibody; coating the antibody modified dendrimer with a long-chain biotin molecule; capturing a target bacterium in a sample liquid by the antibody and long-chain biotin comodified dendrimer; identifying and coupling the long-chain biotin dendrimer in the sample liquid by using streptavidin modified nano-magnetic beads; and carrying out separation and weight suspending on the captured bacterium, wherein the weight suspending solution can be directly used for subsequent analysis. Compared with a traditional bacterium magnetic separation method, the method is more suitable for magnetically separating bacterium in a complex matrix, so that the target bacterium separation efficiency in a sample can be improved.

Description

technical field [0001] The invention relates to the field of biotechnology, in particular to a method for isolating food-borne pathogenic bacteria based on nano magnetic beads. Background technique [0002] Foodborne pathogen contamination is one of the major problems of food safety in my country. According to WHO statistics, about one-third of people in developed countries are infected with food-borne diseases every year, and 2.2 million people in the world die every year due to food-borne diseases. In my country, the number of cases of food poisoning is between 200,000 and 400,000 per year, most of which are caused by food-borne pathogens except for accidents. Staphylococcus aureus (Staphylococcus aureus, SA) As one of the common food-borne pathogenic bacteria, it is the only pathogenic bacteria allowed to exist in a limited amount in quick-frozen brand food by the Ministry of Health of my country. However, the poisoning incidents caused by it occur from time to time, a...

AI Technical Summary

Problems solved by technology

However, the current separation technology based on micron-scale immunomagnetic beads has many limitations: 1) Compared with nano-scale magnetic beads, the specific surface area of ​​micron-scale magnetic beads is small, which reduces the capture efficiency of magnetic beads; Particle nature, which combines with bacterial cells through a multiphase reaction (multiphase reaction), usually takes longer to specifically capture bacterial cells in the food matrix; 3) Micron magnetic beads have poor monodispersity 4) The traditional immunomagnetic separation technology often couples antibody molecules directly to immunomagnetic beads, which often leads to a large decrease in antibody activity and a change in the spatial direction of the antibody, increasing the The steric hindrance effect between antibodies is increased, thereby reducing the capture efficiency of antibodies; 5) The nature of the food matrix is ​​complex and the concentration of non-target pathogenic bacteria (miscellaneous bacteria) is large, and micron magnetic beads are prone to non-specific adsorption, making it difficult to achieve Specific separation of target bacteria in food sample liquid; 6) Excessive concentration of micron magnetic beads will cause damage to bacterial cells (the magnetic field causes the magnetic beads on the cell surface to attract each other, causing the cells to be squeezed or even ruptured), resulting in failure of separation; (7) When magnetic beads are coupled to antibodies, hydrophobic adsorption or chemical coupling is generally used to link active antibodies to the surface of magnetic beads

If the distance between the antibody and the surface of the magnetic bead is too close, due to the nature of the magnetic bead itself and the hydrophobic or strong hydrophilic groups remaining on the surface, it is easy to cause changes in the spatial conformation of the antibody, resulting in a decrease in the biological activity of the antibody

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