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Genotypic Diversity among Bacillus cereus and Bacillus thuringiensis Strains
C R Carlson1, D A Caugant, A B Kolstø
1Biotechnology Centre of Oslo and Institute of Pharmacy, University of Oslo, 0316 Oslo 3, Norway.
Applied and Environmental Microbiology
|June 1, 1994
Summary
Pulsed-field gel electrophoresis (PFGE) and multilocus enzyme electrophoresis (MEE) could not differentiate Bacillus cereus and Bacillus thuringiensis strains. Genetic analysis suggests these two bacterial species should be considered a single species.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Bacillus cereus and Bacillus thuringiensis are closely related bacterial species.
- Distinguishing between these species is important for various applications, including food safety and entomopathogenicity.
Purpose of the Study:
- To genetically differentiate Bacillus cereus and Bacillus thuringiensis using molecular techniques.
- To investigate the genetic relatedness and taxonomic status of B. cereus and B. thuringiensis.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) was used to analyze the genomic profiles of 24 B. cereus and 12 B. thuringiensis strains.
- Multilocus enzyme electrophoresis (MEE) was employed to assess genetic variation across 15 chromosomal genes.
- Hybridization assays were performed using probes for insecticidal toxin genes (cryIA) and transposons (Tn4430).
Main Results:
- PFGE revealed distinct genomic profiles for each of the 36 strains analyzed.
- MEE identified 27 distinct multilocus genotypes among the strains.
- Neither PFGE nor MEE could differentiate between B. cereus and B. thuringiensis.
- Extrachromosomal DNA hybridization indicated the presence of insecticidal toxin and transposon genes in some strains.
Conclusions:
- The genetic data from PFGE and MEE strongly suggest that B. cereus and B. thuringiensis are not distinct species.
- B. cereus and B. thuringiensis should be reclassified as a single species based on their genetic similarity.
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