Spore Germination Apparatus in Clostridium botulinum Group I and II

Pye, Hannah (2017) Spore Germination Apparatus in Clostridium botulinum Group I and II. Masters thesis, University of East Anglia.

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Spore germination is a significant step in the transformation of dormant spores into exponentially dividing vegetative cells, and in the case of Clostridium botulinum in the formation of the deadly botulinum neurotoxin. The ability of nutrient and non-nutrient germinants to induce germination of strains Af84 (C. botulinum Group I) and Eklund 17B (C. botulinum Group II) was established by measuring the change in optical density and by microscopic observation. Germination of strains Af84 and Eklund 17B was initiated by the nutrient germinants L-alanine and L-cysteine and the non-nutrient germinants dodecylamine (DDA) and lysozyme, but not by calcium dipicolinic acid (CaDPA). Heating spores of strain Af84 for 4 hours at 95°C delivered a 3-log reduction in viability. Heat damaged spores of strain Af84 could not be recovered using lysozyme, L-alanine or DDA. Thermal death of spores of strain Eklund 17B occurred within 2 minutes of heating at 85°C, and resulted in a 5-log reduction in viability. The presence of lysozyme (10μg/ml) increased the recovery of heat damaged spores of strain Eklund 17B, however, the presence of L-alanine and DDA had no effect. The timing of DPA release in relation to cortex hydrolysis is still unknown in C. botulinum, however this study found that DPA is released within 18 hours of germinant addition in strain Af84 and within 50 minutes for strain Eklund 17B. In addition, the average DPA concentration per spore of strains Af84 and Eklund 17B was shown to be 1.9pg and 2.1pg, respectively. Results obtained indicate that part of the germination apparatus in Group II strain Eklund 17B is damaged by heating, rather than the spore DNA. Understanding the mechanisms involved in spore germination can improve the control of botulinum neurotoxin forming clostridia, prevent foodborne botulism, and thereby contribute to the microbiological safety of foods.

Item Type: Thesis (Masters)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Nicola Veasy
Date Deposited: 23 Mar 2018 14:57
Last Modified: 30 Sep 2018 00:38
URI: https://ueaeprints.uea.ac.uk/id/eprint/66583


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