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Formation Of Mixed Biofilms Of Vibrio Parahaemolyticus And Vibrio Cholerae

Posted on:2019-12-30Degree:MasterType:Thesis
Country:ChinaCandidate:X R DongFull Text:PDF
GTID:2370330566974521Subject:Food Science and Engineering
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Bacterial Biofilm is a kind of membrane that is formed after many bacteria adhere to biological or non-biological surfaces and secrete extracellular polysaccharides(EPS),proteins,lipids,and DNA,and encapsulates them.It is an existing form of bacteria that adapts to the natural environment and is conducive to its own survival.Most of the bacteria in nature can form biofilms,and the formed biofilms exist in a mixed biofilm state.Vibrio parahaemolyticus(VP)and Vibrio cholera(VC)are important food-borne pathogens in seafood.Vibrio parahaemolyticus and Vibrio cholerae often co-exist in aquatic products and can form a mixed biofilm on the surface of aquatic products.This can easily lead to food cross-contamination,resulting in food corruption or hidden dangers in the spread of diseases,posing a great threat to food safety.Therefore,the study of mixed biofilms formed by Vibrio parahaemolyticus and Vibrio cholerae is of great significance for the control of harmful biofilms in foods.In this study,VC and VP were used as the research object.First,the formation process of single-culture VC,VP and mixed biofilms was studied.Biopsies were measured at 4,8,12,24,36,48,60,and 72h,respectively.The formation of capsules;Secondly,the single cultured VC strains,VP bacteria,and blends at different temperatures(4,15,25,37?)and different salinity(1,2,3,4,5,6,7%)were studied.The bacterial biofilm was formed;finally,the effect of electrolysis water treatment on the biofilm formation of single cultured VC,VP,and mixed strains was investigated by fluorescence quantitative PCR and fluorescence in situ hybridization,which is an effective control of mixed organisms formed by VC bacteria and VP bacteria.The coating provides the foundation.1.Study on the formation of mixed biofilms of Vibrio parahaemolyticus and Vibrio choleraeAt 4 h,8 h,12 h,24 h,36 h,48 h,60 h,and 72 h,the formation of VP,VC,and their mixed biofilms under conditions alone was determined.Crystal violet staining,plate colony counting,and determination of extracellular polysaccharides and extracellular protein were determinant.Using laser confocal microscopy(CLSM)for biofilm formation under single culture and mixed conditions.Although the amount of mixed biofilm formed was between VC and VP,in the process of formation of the mixed biofilm,the change of the amount of biofilm after the maturation period was small,and the resistance to the environment was enhanced.There are more living bacteria in the mixed biofilm,and changes in extracellular proteins and extracellular polysaccharides during the formation of mixed biofilms indicate that they may play an important role in resisting gradual adaptation to the environment.In the process of forming biofilm together with VP,although the total amount of mixed biofilm is reduced,there are more viable bacteria in the mixed biofilm,which may cause greater harm.The change of the membrane during the formation of mixed biofilms and biofilms can provide the basis for the control of harmful biofilms.2.Influence of environmental factors on biofilm formation of Vibrio parahaemolyticus and Vibrio choleraeBy studying the biofilm formation of VC,VP and mixed bacteria in single culture under different temperature(4,15,25,37 ?)and different salinity(1,2,3,4,5,6,7%).The results showed that the biofilm formation capacity of the mixed biofilm at 37 ? was higher than the number of viable cells in the biofilm compared to the single cultured VC and VP bacteria.The biofilm formed by the mixed bacteria under the condition of salinity of 5%showed stronger resistance to high salinity than the VC and VP bacteria mono-cultured.Mixed biofilms have more biofilms and more viable bacteria.3.Removal of Vibrio parahaemolyticus and Vibrio cholerae mixed biofilmFluorescence quantitative PCR and fluorescence in situ hybridization(FISH)were used to study the effect of electrolysis water treatment on biofilms formed by single cultured VC,VP,and mixed bacteria.The results showed that the mixed biofilm showed stronger resistance to the treatment of electrolyzed water than that of the monoculture biofilm.The results of fluorescence quantitative PCR showed that the mixed biofilm compared with the monoculture biofilm,after electrolysis of water treatment,the total bacterial count in the mixed biofilm decreased less,not as single-culture VC bacteria and VP bacteria showed Significant reduction.The mixed biofilm was observed by FISH.The results showed that compared with the biofilm of single culture,the biofilm did not show significant reduction in the biofilm and no large hole-like structure appeared.It shows that mixed biofilm water treatment is resistant.
Keywords/Search Tags:mixed biofilm, environmental factors, Vibrio parahaemolyticus, Vibrio cholerae, confocal laser scanning, fluorescence quantitative PCR, fluorescence in situ hybridization
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