Induction Of VBNC Escherichia Coli O157:H7 And Detection Method Research On Pathogenic Bacteria

Viable but nonculturable state,or simply ‘VBNC state' for short,which cannot form colonies or can form invisible microscopic colonies on the common medium,but still have metabolism.In the field of bacterial detection,the plate counting method is just fit for detection bacteria that can grow on conventional media.However,this method leads to VBNC leak detection.In view of the great potential threat from E.coli O157: H7 with the wide range of transmission routes,highly infectivity,toxicity and easy entry into VBNC state.Therefore,it is urgent to study the status of the VBNC,and to provide theoretical basis and scientific basis for food processing and safety control caused by pathogenic microorganisms.At the same time,it also needs to develop the rapid detection method for foodborne pathogens.There will be practical significance in food safety test and control.The ability to enter VBNC state of the bacteria,under different nutritional conditions,at respectively 4? and-20?,has been studied at an early stage.Due to important role of E.coli O157: H7,Staphylococcus aureus and Salmonella in the food safety fields,the later stage of this study is concentrated to establish one identification method for the three kinds of pathogenic bacteria.In this study,the changes of bacteria shapes are used for determination of the ability to enter VBNC state and recoverability of E.coli O157: H7 under different nutritional conditions,at 4? and-20? respectively.The results suggested that E.coli O157: H7 reserved at-20? and LB culture medium were easier to enter VBNC state.On the other hand,the bacteria in VBNC state with smaller volumes and irregular morphology,some of them tended to gathering.In order to identify E.coli O157: H7 and Staphylococcus aureus,Salmonella at the same time,and distinguish the dead and live state of the three important food-borne pathogens,mPCR and PMA-mPCR were employed for identification and assessment with a combination of artificial food samples.With good stability and corresponding sensitivity,this method could identify the three kinds of bacteria and accurately distinguish the dead from the viable.For rapid detection,surface enhanced Raman spectroscopy was also employed in initial identification research.Foodborne pathogens have always been a major threat to food safety.This study not only explored the specific VBNC status of E.coli O157: H7,but also established a variety of methods for rapid detection of foodborne pathogens and accurately distinguished the dead from the viable of foodborne pathogenic.These are of great significance to food safety and have broad prospects for development in the field of foodborne pathogens,and also provide a theoretical basis for the future research.