- Title
- Genomic and flow cytometric studies of Clostridium sporogenes, a non-toxigenic surrogate for Clostridium botulinum
- Creator
- Bradbury, Mark
- Date
- 2014
- Type
- Text; Thesis; PhD
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/97216
- Identifier
- vital:10157
- Identifier
- https://library.federation.edu.au/record=b2633659~S4
- Abstract
- Clostridium sporogenes and Group I Clostridium botulinum are two bacterial species belonging to the same phylogenetic group, primarily differentiated by the expression of botulinum neurotoxin. Both organisms are of significant commercial importance in regards to the spoilage of and/or disease in thermally processed food products due to their ability to form heat resistant spores. As such, these species are often used as the target organism for the design of thermal inactivation processes, particularly in regards to thermal sterilisation. Two specific aspects pertaining to these organisms were investigated to further enhance knowledge with respect to their use in thermal processing studies: the genetic relationship between C. sporogenes and Group I C. botulinum; and the mechanism of heat resistance in spores of C. sporogenes. The first part of this thesis describes the assembly, annotation and analysis of the draft genome of C. sporogenes PA 3679 (the most widely used surrogate for Group I C. botulinum). These data allowed identification of unique variants genes related to spore germination, analogous toxin regions and mobile elements between species. MLST analysis revealed that phylogeny was an ineffective indicator of toxigenicity in this group and thus prompted a pan-genomic analysis. The pan-genome of C. sporogenes/Group I C. botulinum was found to consist of 8799 coding sequences (CDS’s) and a core genome consisting of 1590 CDS’s. Analysis of this pan-genome revealed the significant role that mobile genetic elements have played in genetic diversity within this group of organisms. The second part of this thesis investigated the heat inactivation of C. sporogenes PA 3679 spores in regards to structural variation and population heterogeneity. A novel flow cytometric approach was developed and utilised to investigate isothermal spore inactivation; and implications of the impact of NaCl on the intrinsic variability throughout this process and during a subsequent recovery period. Based on these approaches a possible mechanistic description for the thermal inactivation of spores was developed. Together, these studies present significant evidence supporting the continued suitability of C. sporogenes as a surrogate for Group I C. botulinum, whilst also enhancing the understanding of clostridial spore inactivation during a moist heat process.; Doctor of Philosophy
- Publisher
- Federation University Australia
- Rights
- Copyright Mark Bradbury
- Rights
- Open Access
- Rights
- This metadata is freely available under a CCO license
- Subject
- Clostridium sporogenes; Non-toxigenic surrogate; Clostridium botulinum
- Full Text
- Thesis Supervisor
- Vriesekoop, Frank
- Hits: 1096
- Visitors: 1698
- Downloads: 639
| Thumbnail | File | Description | Size | Format | |||
|---|---|---|---|---|---|---|---|
| View Details Download | SOURCE1 | Australian Digital Thesis | 6 MB | Adobe Acrobat PDF | View Details Download |