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Genomic and physiological variability within Group II (non-proteolytic) Clostridium botulinum
Sandra C Stringer1, Andrew T Carter, Martin D Webb
1Institute of Food Research (IFR), Norwich Research Park, Colney, Norwich NR4 7UA, UK. sandra.stringer@ifr.ac.uk
BMC Genomics
|May 18, 2013
Summary
Group II Clostridium botulinum strains form a stable genetic group, but genomic and physiological data reveal two distinct subsets: one for types B and F, and another for type E. This clarifies the genetic diversity within this bacterium.
Area of Science:
- Microbiology
- Genomics
- Bacterial Pathogenesis
Background:
- Clostridium botulinum Group II (non-proteolytic) genetic and physiological variability is poorly understood.
- Previous studies focused on Group I (proteolytic) C. botulinum, leaving a knowledge gap for Group II strains.
- Botulinum neurotoxin production by C. botulinum poses significant public health concerns.
Purpose of the Study:
- To investigate the genetic relatedness and physiological characteristics of Group II Clostridium botulinum strains.
- To differentiate between subtypes within Group II C. botulinum based on genomic and phenotypic data.
- To understand the evolutionary relationships and genetic stability of Group II C. botulinum.
Main Methods:
- Whole genome sequencing of Clostridium botulinum Group II strain Eklund 17B (NRP).
- Construction of a whole genome DNA microarray for comparative genomic indexing.
- Comparative genomic indexing of 43 Group II C. botulinum strains (types B, E, and F).
- Physiological characterization including carbohydrate fermentation, minimum growth temperature, and NaCl tolerance.
Main Results:
- Whole genome indexing confirmed a stable genetic background for Group II C. botulinum strains isolated over 75 years.
- Type B and F toxin-producing strains clustered closely, differing mainly in toxin cluster genes.
- Type E toxin-producing strains formed a distinct genetic subset, supported by differential carbohydrate fermentation.
- No significant differences were observed in growth temperature or NaCl tolerance between subsets.
- Tellurite resistance gene (tehB) presence correlated with type B/F strains, absent/diverged in type E strains.
Conclusions:
- Group II Clostridium botulinum represents a genetically cohesive group.
- Genomic and physiological analyses reveal two distinct subsets within Group II: one encompassing type B and F strains, and another comprising type E strains.
- These findings provide a clearer understanding of the genetic structure and diversity within non-proteolytic C. botulinum.
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