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Chapter 5 dry and rough (bdar) morphology occurs through congo red and coomassie blue binding to curli only (no cellulose binding protein). The pink dry and rough (pdar) morphotype is indicative of the coomassie blue binding to cellulose binding protein in the absence of curli. The finding binding of that coomassie blue only results in a pink colour may be a reflection of both congo red and coomassie blue contained in the one agar plate. The smooth and white (saw) morphotype is indicative of no binding of either the congo red or coomassie dyes [4]. Malcova and colleagues recently described the ability of Salmonella strains deficient of curli and cellulose to form a biofilm, due to over-production of a capsular polysaccharide resulting in a smooth, brown and mucoid colony morphotype (sbam) on CR agar [86]. Table 5.1: Colony Morpholgy Using Congo Red Agar Morphology Colony Curli Cellulose Biofilm Reference Name Morphology Former rdar Red, dry and rough colony morphology + + Dense biofilm former [77] bdar Brown, dry and rough colony morphology + - Less dense biofilm former [77] pdar pink, dry and rough colony morphology - + Less dense biofilm former [77] sbam saw smooth, brown and mucoid morphology smooth and white morphology - - Less dense capsular polysaccharide biofilm former - - Unable to form a dense biofilm [86] [77] Page 155
Chapter 5 5.1.2. Previous research using the colony morphology assessment Römiling and colleagues demonstrated that knocking out the gene encoding for curli expression (curli subunit genes CsgA) resulted in an altered colony morphology of S. Typhimurium on CR agar. The colony morphology changed from rdar to pdar based on this knockout process. This change was associated with less dense biofilm formation by strain [77, 167]. In this case, biofilm was examined through the use of a pellicle test (biofilm formed on air-liquid interface) cells on glass [77] and by a electron microscopic examination of stained biofilm [77]. Additionally, Römiling et al. demonstrated that mutation of the AgfD gene (involved in encoding for cellulose production) also altered the colony morphology resulting in a brown, dry and rough colony morphology (bdar) [167, 225]. The bdar strains also produced a more fragile biofilm than the wild type strain when examined using a pellicle formation model and assessing the force needed to disaggregate the pellicle [167, 225]. Moreover, as a result of this research, Römiling and colleagues demonstrated that the mutants lacking both genes in S. Typhimurium (LT2 mutants) were unable to form a biofilm and could be identified as smooth and white (saw) on CR agar [77, 167, 225] . Malcova et al. recently reported that S. Typhimurium strains that do not appear to produce curli or cellulose based on morphology on CR agar, were capable of forming a dense biofilm using the microtitre plate based method [86]. The formation of capsular polysaccharide by the strains resulted in a smooth brown and mucoid colony morphology on congo red agar. Malcova et al. indicated that this phenomenon (production of a biofilm through the formation of a capsule without cellulose or curli) was not only associated with S. Typhimurium DT104, but was also found in 3 strains of S. Montevideo and 1 strain of S. Derby [86]. The presence of capsular polysaccharides that may be involved in biofilm formation in the Page 156
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Salmonella enterica - biofilm forma
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Table of Contents Page Number 1.16.
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Table of Contents Page Number 4.1.2
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Table of Contents Page Number 6.8.4
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List of Abbreviations Table Page Nu
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List of Abbreviations List of Abbre
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Summary of Content Summary of Conte
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“To show your true ability is alw
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Acknowledgements ever met, Fiona th
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Acknowledgements This Ph.D. thesis
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Chapter 1 1.1. Salmonella Salmonell
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Chapter 1 may impose enormous costs
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Chapter 1 cracks or penetration of
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Chapter 1 detected by agglutination
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Chapter 1 become colonized with >10
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Chapter 1 antigens [z27],[z45] [1].
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Chapter 1 S. Agona has also been im
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Chapter 1 isolated from undercooked
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Chapter 1 The S. Typhimurium strain
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Chapter 1 ecosystem with the use of
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Chapter 1 [82]. Previous research h
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Chapter 1 to genes involved in flag
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Chapter 1 observation has also been
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Chapter 1 [119] and flow cell react
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Chapter 1 based disinfectant) the s
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Chapter 1 formation of two strains
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Chapter 1 shield the S. Agona cells
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Chapter 1 Key Objectives of this st
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Chapter 2 2. Abstract Food-borne pa
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Chapter 2 indicated that there may
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Chapter 2 taken from industrial set
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Chapter 2 2.1.4. CDC Biofilm Reacto
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Chapter 2 can be performed without
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Chapter 2 To summarise, previous au
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Chapter 2 2.3. Methods for examinin
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Chapter 2 and the biofilm formed th
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Chapter 2 2.4. Statistical Analysis
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Chapter 2 Table 2.1: Strain charact
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Chapter 2 XII. The gas port and med
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Chapter 2 II. Primary fixative cons
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Chapter 2 IX. Once the conditions w
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Chapter 2 Figure 2.1: Image of CBR
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Chapter 2 2.6. Results 2.6.1. Asses
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Chapter 2 2.6.3. SEM Analysis of su
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Chapter 2 Figure 2.6: Complete remo
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Chapter 2 2.6.5. Mean log 10 densit
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Chapter 2 2.6.6. Mean log 10 densit
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Chapter 2 Table 2.5: Mean log 10 de
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Chapter 2 The results displayed in
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Chapter 2 Table 2.7: Difference bet
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Chapter 2 Table 2.8: The mean log 1
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Chapter 2 Figure 2.7: Graph of the
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Chapter 2 also used “high” soni
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Chapter 2 2.8. Summary All 13 strai
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Chapter 3 3. Abstract It has been e
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Chapter 3 classified as persistent
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Chapter 3 was plated onto TSA for e
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Chapter 3 Figure 3.1: The mean log
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Chapter 3 Figure 3.3: SEM image of
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Chapter 3 Table 3.2: Difference bet
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Chapter 3 3.4.3. Intra-serovar vari
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Chapter 3 3.4.4. Strain variation i
Page 126 and 127: Chapter 3 3.4.5. The density of bio
Page 128 and 129: Chapter 3 3.5. Discussion As illust
Page 130 and 131: Chapter 3 As discussed in section 3
Page 132 and 133: Chapter 3 increased biofilm appeare
Page 134 and 135: Chapter 4 Examining the efficacy of
Page 136 and 137: Chapter 4 through laboratory based
Page 138 and 139: Chapter 4 acid and quaternary ammon
Page 140 and 141: Chapter 4 the surface the temperatu
Page 142 and 143: Chapter 4 availability of multiple
Page 144 and 145: Chapter 4 peracetic acid (100, 200,
Page 146 and 147: Chapter 4 As discussed previously,
Page 148 and 149: Chapter 4 Dey/Engley (Difco) neutra
Page 150 and 151: Chapter 4 sterilisation was achieve
Page 152 and 153: Chapter 4 IX. Aliquots of 100µl of
Page 154 and 155: Chapter 4 XV. XVI. XVII. XVIII. XIX
Page 156 and 157: Chapter 4 4.3. Results 4.3.1. Suspe
Page 158 and 159: Chapter 4 Table 4.3: Mean log 10 de
Page 160 and 161: Chapter 4 Benzalkonium chloride was
Page 162 and 163: Chapter 4 4.4. Discussion Suspensio
Page 164 and 165: Chapter 4 effective at eliminating
Page 166 and 167: Chapter 4 Surprisingly, Nguyen et a
Page 168 and 169: Chapter 4 though a contact time of
Page 170 and 171: Chapter 4 provide a more standardis
Page 172 and 173: Chapter 4 hours instead of the stan
Page 174 and 175: Chapter 5 5. Abstract Examining bio
Page 178 and 179: Chapter 5 absence of curli and cell
Page 180 and 181: Chapter 5 studies such as the micro
Page 182 and 183: Chapter 5 discussed in chapter 4. T
Page 184 and 185: Chapter 5 5.2. Methods 5.2.1. Colon
Page 186 and 187: Chapter 5 XIII. XIV. XV. XVI. XVII.
Page 188 and 189: Chapter 5 XVI. XVII. XVIII. XIX. XX
Page 190 and 191: Chapter 5 5.3.2. Repeatability of m
Page 192 and 193: Chapter 5 Figure 5.2: Stained biofi
Page 194 and 195: Chapter 5 was formed at room temper
Page 196 and 197: Chapter 5 Table 5.3: The density of
Page 198 and 199: Chapter 5 5.3.4. The density of bio
Page 200 and 201: Chapter 5 Table 5.6: The difference
Page 202 and 203: Chapter 5 Table 5.7: The difference
Page 204 and 205: Chapter 5 Table 5.8: Summary of ass
Page 206 and 207: Chapter 5 interpretation therefore
Page 208 and 209: Chapter 5 measures of S. enterica b
Page 210 and 211: Chapter 5 cells peaks [165, 191]. D
Page 212 and 213: Chapter 5 5.5. Limitations of the s
Page 214 and 215: Chapter 6 Discussion of S. enterica
Page 216 and 217: Chapter 6 However, a number of auth
Page 218 and 219: Chapter 6 It is of interest to exam
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Page 222 and 223: Chapter 6 attributable to a small n
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Chapter 6 undetermined. However, th
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Chapter 6 reason for this may be du
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Chapter 6 Moreover, based on the re
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Chapter 6 responsible for increased
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Chapter 6 not fully capture the ran
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Chapter 6 However, the extent of bi
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Chapter 6 6.10. Conclusions and rec
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Chapter 6 studies may solve some of
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Bibliography Bibliography Page 221
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Bibliography 12. T. Takata, J.L., H
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Bibliography 29. Barker, J., M. Nae
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Bibliography 47. Threlfall, E.J., H
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Bibliography 65. CDC. Investigation
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Bibliography 83. Ledeboer, N., Frye
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Bibliography 100. Chia, T., Goulter
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Bibliography 117. Buckingham-Meyer,
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Bibliography 133. European Committe
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Bibliography Supernatant of a Hafni
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Bibliography 165. Díez-García, M.
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Bibliography cultivation of Staphyl
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Bibliography Compounds. 2012. Appli
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Bibliography 215. Buck, et al., A q
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Bibliography Canadian Journal of Ps
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Appendix 1 Appendix 1— List of Re
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Appendix 1 Appendix 1 - List of Equ
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Appendix 2 Colour index High outlie
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Appendix 3 Appendix 3-Figure 2: PFG
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Appendix 4 Poster Presentation Envi
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