Title Page
ABSTRACT
Contents
Nomenclature 8
1. Introduction 9
2. Materials and Methods 11
2.1. Bacterial strains and cell suspension 11
2.2. Preparation of coupons 11
2.3. Attachment and biofilm formation 12
2.4. X-ray irradiation 12
2.5. Enumeration of biofilm cells 13
2.6. Modeling of biofilm survival and calculation of D values 14
2.7. Measurement of biofilm EPS 15
2.8. Statistical analysis 16
3. Results 17
3.1. Inactivation of biofilm cells formed on various food-contact surfaces after X-ray irradiation 17
3.2. Modeling X-ray inactivation of E. coli O157:H7, S. Typhimurium, and L. monocytogenes biofilms on food contact surfaces 21
3.3. Calculation of D₁d and D₅d values based on each selected model[이미지참조] 23
3.4. Removal of EPS from pathogen biofilms using X-ray irradiation 25
4. Discussion 28
Bibliography 30
Summary in Korean 35
Table 1. Statistical measures and parameter values of the Log-linear + shoulder, Weibull, Biphasic, and Biphasic + shoulder model for inactivation of Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes biofilms formed on PVC, STS 2B, and Teflon coupons irradiated...[원문불량;p.14] 22
Table 2. D₁d and D₅d values for E. coli O157:H7, S. Typhimurium, and L. monocytogenes biofilms formed on PVC, STS 2B, and Teflon coupons irradiated with X-ray based on the Log-linear +...[이미지참조] 24
Table 3. Removal of exopolysaccharides associated with E. coli O157:H7 biofilm on PVC, STS 2B, and Teflon surfaces following X-ray irradiation. 26
Table 4. Removal of exopolysaccharides associated with S. Typhimurium biofilm on PVC, STS 2B, and Teflon surfaces following X-ray irradiation. 27
Fig 1. Survival of (a) Escherichia coli O157:H7, (b) Salmonella Typhimurium, and (c) Listeria monocytogenes biofilms on PVC, STS 2B, and Teflon coupons irradiated with different doses of X- ray. 20