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Table of Contents
Page Number
1.16.2. Methods for evaluating the efficacy of disinfectants 29
against Salmonella biofilm
1.16.3. Effect of age of biofilm on cell recovery 32
Key Objectives of this study 35
Chapter 2-Assessing the density of a 48 hour S. enterica biofilm
established using the CDC biofilm reactor
2.1. Introduction 37
2.1.1. Surface differences 38
2.1.2. Strains/Serovars 40
2.1.3. Origin of strains 40
2.1.4. CDC Biofilm Reactor 43
2.1.5. Advantages and Disadvantages of the CBR 43
2.1.6. Reproducibility of biofilm studies using the CBR 45
2.2. Examining biofilm density and reproducibility using 47
other biofilm reactor models
2.3. Methods for examining biofilm density and substrata 49
2.3.1. Atomic Force Microscopy 49
2.3.2. Scanning Electron Microscopy (SEM) 49
2.3.3. Other methods for examining and enumerating biofilm 50
cells
2.3.4. Sonication as a method of removal for enumeration 51
2.4. Statistical Analysis 53
2.5. Methods 56
2.5.1. 48 hour biofilm development model 56
2.5.2. Scanning Electron Microscopy 58
2.5.2.1. Primary and Secondary 58
2.5.2.2. Gold Coating Samples 59
2.5.2.3. SEM Analysis 60
2.5.3. AFM Analysis 61
2.5.4. Validation of removal techniques 62
2.6. Results 65
2.6.1. Assessment of Quality control experiments 65
2.6.2. Scanning Electron Microscopy 66
2.6.3. SEM analysis of surfaces to confirm biofilm removal via 67
sonication.
2.6.4. Mean log 10 density of S. enterica biofilm 70
iii