Study On The Detection Method Of Food-borne Pathogenic Bacteria In Food

Pathogenic bacteria have always been a huge threat to human safety and health,and millions of people die from food-borne pathogen infections every year.In the past,high temperatures during cooking can kill all bacteria,but with the popularity of packaged foods,bacterial infections may occur during processing,packaging,and transportation.Dairy products,drinking water,and beverages are all effective for pathogenic bacteria carrier.Therefore,the establishment of a fast and convenient method for detecting pathogenic bacteria in food is of great significance to reduce the threat of pathogenic bacteria infection to the human body.This article has established three rapid detection methods for E.coli O157:H7,Cronobacterium,Salmonella,Staphylococcus aureus and Listeria monocytogenes commonly found in food.(1)Establish a molecular capture lateral chromatography test paper detection method for isothermal chain exchange amplification of Cronobacterium in milk powderHerein,we have developed a new detection method for rapid and easy quantitative identification of Cronobacter spp.in infant formula milk powder.This method well couples the advantages of isothermal strand exchange amplification(SEA)and molecular capturing lateral flow strip(LFS).The presence of Cronobacter spp.DNA template can be isothermally and exponentially amplified by SEA with a pair of labeled functional primers without thermal controller device.The high amplification efficiency of SEA enables the accumulation of plentiful dual-labeled amplicons that can be captured by a molecular capturing LFS with the using of fluorescent microsphere(FM)as tagger,which can be excited at 365 nm and the signal at 625 nm can be acquired for the quantitative analysis.The Cronobacter spp.in the concentration from 101 to 106 cfu/m L can be accurately determined with the visual detection limit of 10 cfu/m L within less than one hour even in the complex infant formula milk powder.We expect this unique SEA-LFS method with its favorable assay performance can be a powerful analytical protocol in the field of foodborne pathogen detection.(2)Establish a paper-based detection method for Salmonella Typhimurium in water based on surface enhanced Raman spectroscopyThe study prepared nanoparticles with gold nanoparticles as the structural substrate,rhodamine 6G as the probe molecule,and silver shell as the reinforcement substrate.The mixed cellulose membrane was used to enrich the Salmonella Typhimurium labeled by the nanoparticles,and then the Raman on the membrane surface was collectedto quickly detect Salmonella Typhimurium in contaminated water.The results showed that within 30 min,Salmonella Typhimurium in the lake water could be detected,with a concentration ranging from 101 to 106cfu/m L.This work has simplicity,rapidity,cheapness,anti-interference ability and durability,which opens up a new way for the development of detection of pathogenic bacteria in water.(3)Establish a self-made portable double-layer filter device detection method based on surface enhanced Raman spectroscopy for multiple pathogenic bacteria in waterHerein,we reported the engineering of a homemade portable double-layer filtration devicebased on an injection syringe.The core elements of the device are two installed filtration membranes with different pore sizes.The upper filtration membrane is used for intercepting large interfering objects(intercepting membrane),while the lower filtration membrane is used for collecting multiple targets(concentration membrane).Their combinationcan make the contaminated environmental water,exemplified by lake water,fast seeps through the device and only retainedthe target bacteriaof Escherichia coli O157:H7(E.coli O157:H7),Staphylococcus aureus(S.aureus),and Listeria monocytogenes(L.monocytogenes)on the lower concentration membrane.Integrating with surface-enhance Raman spectra(SERS)detection platform to decode the SERS-Tags(SERS-Tag CVa,SERS-Tag R6 G,and SERS-Tag MB)already attached on each of the enriched bacteria,we realized the fast separation,concentration,and detection of multiple pathogenic bacteria from a bulk of contaminated environmental water.Results shown that within 30 min,all the target bacteria from the lake water can be simultaneously detected with a concentration range from 101 to 106cfu/m L and a lowest concentration of 10 cfu/m L.This work highlights the simplicity,rapidness,cheapness,anti-interference ability,and robustness in detecting multiple waterborne pathogens,opening a new avenue for facilitating the development of versatile analytical tools for water and food safety monitoring and management.