Inactivation of Microorganisms by Gamma Irradiation – Bacillus Atropheus Spores and Erwinia Herbicola


  1. Hilsen, R.E.
  2. Kournikakis, B.
  3. Ford, B.
Corporate Authors
Defence R&D Canada - Suffield, Ralston ALTA (CAN)
The purpose of this study was to establish kill curves detailing the sterilization efficiency of 60Co gamma irradiation on non-pathogenic vegetative and spore preparations. This was done by testing the viability of the microorganisms over a range of gamma irradiation exposures. The procedures used to carry out the work will be used in future sterilization studies of pathogenic microorganisms for later use as antigen reagents. The initial use of non-pathogenic organisms provided a low-risk method for familiarization with the protocol and resolution of any potential problems. Results showed that 4.0 kGy irradiation over a 12 minute period was required for complete inactivation of Erwinia herbicola. The inactivation of Bacillus atropheus (formerly Bacillus subtilis var globigii (BG)) dry powder required 25kGy over 75 minutes and the inactivation of Bacillus atropheus in liquid suspension required 35 kGy over 105 minutes. These results showed that vegetative cells and spore preparations can be successfully sterilized by gamma irradiation in a short amount of time. These results will be used as starting points to establish kill curves for Risk Group 3 organisms such as Bacillus anthracis and Yersinia pestis.

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Cobalt-60;gamma irradiation;kill curve;Bacillus atropheus;Erwinia herbicola
Report Number
DRDC-SUFFIELD-TM-2005-236 — Technical Memorandum
Date of publication
01 Dec 2005
Number of Pages
Hardcopy;Document Image stored on Optical Disk

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