Germination and persistence of Bacillus anthracis and Bacillus thuringiensis in soil microcosms
Article first published online: 13 SEP 2014
© 2014 Crown Copyright. Journal of Applied Microbiology © 2014 Society for Applied Microbiology This article is Published with the permission of the Controller of HMSO and Queen's Printer for Scotland
Journal of Applied Microbiology
Volume 117, Issue 5, pages 1274–1282, November 2014
How to Cite
Bishop, A.H. (2014), Germination and persistence of Bacillus anthracis and Bacillus thuringiensis in soil microcosms. Journal of Applied Microbiology, 117: 1274–1282. doi: 10.1111/jam.12620
- Issue published online: 14 OCT 2014
- Article first published online: 13 SEP 2014
- Accepted manuscript online: 7 AUG 2014 02:51AM EST
- Manuscript Accepted: 4 AUG 2014
- Manuscript Revised: 2 AUG 2014
- Manuscript Received: 6 JUL 2014
- Defense Threat Reduction Agency, U.S.A
- Ministry of Defence, U.K
- Bacillus anthracis ;
- Bacillus thuringiensis ;
- vegetative persistence
Decontaminating large, outdoor spaces of Bacillus anthracis spores presents significant problems, particularly in soil. Proof was sought that the addition of germinant chemicals could cause spores of B. anthracis and Bacillus thuringiensis, a commonly used simulant of the threat agent, to convert to the less resistant vegetative form in a microcosm.
Methods and Results
Nonsterile plant/soil microcosms were inoculated with spores of B. thuringiensis and two nonpathogenic strains of B. anthracis. A combination of L-alanine (100 mmol l−1) and inosine (10 mmol l−1) resulted in a 6 log decrease in spore numbers in both strains of B. anthracis over 2 weeks at 22°C; a 3 log decrease in B. anthracis Sterne spore numbers was observed after incubation for 2 weeks at 10°C. Negligible germination nor a decrease in viable count occurred in either strain when the concentration of L-alanine was decreased to 5 mmol l−1. Germinated spores of B. thuringiensis were able to persist in vegetative form in the microcosms, whereas those of B. anthracis rapidly disappeared. The pleiotropic regulator PlcR, which B. anthracis lacks, does not contribute to the persistence of B. thuringiensis in vegetative form in soil.
The principle of adding germinants to soil to trigger the conversion of spores to vegetative form has been demonstrated. Bacillus anthracis failed to persist in vegetative form or resporulate in the microcosms after it had been induced to germinate.
Significance and Impact of the Study
The large scale, outdoor decontamination of B. anthracis spores may be facilitated by the application of simple, defined combinations of germinants.