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[Detection of atoxigenic variants in Cl. botulinum type A and B cultures exposed to different treatments]
Abstract:
A possibility of detection of atoxigenic clones in the cultures of Cl. botulinum, types A and B, under conditions of treatment with acridine strains, UV-irradiation and heating of spores was studied. Of the 10 strains investigated, atoxigenic variants were obtained only in 3, belonging to type B; the frequency of formation of atoxigenic clones under the effect of ethidium bronide constituted 36--45.7%, and of the UV-irradiation-4.2%; heating of spores proved to be ineffective. A frequent loss of the toxigenicity sign coincided with the view on the elimination of the episomal determinant of the toxin-formation, not with the mutational nature-of this change. An association between the differences in stability of retention of the toxigenicity signs in various strains and types of Cl. botulinum and possible differences of the corresponding genetic determinants of the toxin formation is discussed.
Insights
Researchers investigated methods to create atoxigenic Clostridium botulinum strains. Ethidium bromide treatment effectively generated atoxigenic variants in type B strains, suggesting episomal loss of toxin genes.
Area of Science:
- Microbiology
- Molecular Biology
Context:
- Clostridium botulinum produces toxins causing botulism.
- Understanding mechanisms of toxin gene loss is crucial for food safety and research.
Purpose:
- To investigate the potential for generating atoxigenic Clostridium botulinum strains.
- To evaluate the efficacy of different treatments (acridine strains, UV irradiation, heat) in eliminating toxin production.
Summary:
- Treatment of Clostridium botulinum types A and B with ethidium bromide and UV irradiation was studied.
- Atoxigenic variants were obtained from three type B strains, with ethidium bromide yielding higher frequencies (36-45.7%) than UV irradiation (4.2%).
- Heating spores was ineffective; loss of toxigenicity is likely due to episomal determinant elimination rather than mutation.
Impact:
- Findings suggest that toxin gene loss in Clostridium botulinum is often mediated by extrachromosomal elements.
- This research aids in developing safer strains for research and potentially for other applications.
- Understanding the genetic basis of toxigenicity stability in different Clostridium botulinum types is important.