Related Experiment Videos
Serotype H5a5b is a major clone within mosquito-pathogenic strains of Bacillus sphaericus
V Zahner1, H Momen, F G Priest
1Department of Biochemistry and Molecular Biology, Oswaldo Cruz Foundation, Manguinhos, Rio de Janeiro, Brazil.
Abstract:
Seventy six mosquito pathogenic strains of Bacillus sphaericus and 10 non-pathogens were examined by pulsed field gel electrophoresis (PFGE) of SmaI-digested chromosomal DNA. Non-pathogenic strains were clearly distinguished from the entomopathogenic types which were assigned to 21 groups (SmaI restriction patterns; SRPs). Some agreement between SRP based on PFGE and serotyping was noted, in particular all 39 strains of serotype 5a5b examined revealed identical SRPs indicating total conservation of the SmaI restriction site in these bacteria. Serotype 5a5b (SRP 12) strains comprise a widely distributed and abundant clonal lineage. Most serotypes, however, were divided into several SRPs. Seven strains from serotype 2a2b were covered in five SRPs in which toxin synthesis was correlated with chromosomal structure. Similarly, toxicity correlated with SRP in strains from serotypes 3 and 6.
Insights
Pulsed field gel electrophoresis (PFGE) differentiated Bacillus sphaericus strains, distinguishing non-pathogens from entomopathogens. Toxin synthesis in pathogenic Bacillus sphaericus correlated with specific chromosomal structures identified by PFGE.
Area of Science:
- Microbiology
- Molecular Biology
- Insect Pathology
Background:
- Bacillus sphaericus is a key bacterial agent for mosquito control.
- Understanding genetic diversity within B. sphaericus is crucial for optimizing its application.
- Previous classification relied on serotyping, which may not fully capture genetic relationships.
Purpose of the Study:
- To genetically differentiate pathogenic and non-pathogenic strains of Bacillus sphaericus.
- To investigate the relationship between genetic profiles and serotypes.
- To explore correlations between chromosomal structure, serotype, and toxin synthesis.
Main Methods:
- Pulsed field gel electrophoresis (PFGE) was used to analyze SmaI-digested chromosomal DNA from 76 pathogenic and 10 non-pathogenic Bacillus sphaericus strains.
- Chromosomal DNA was digested with SmaI restriction enzyme.
- PFGE generated SmaI restriction patterns (SRPs) for each strain.
Main Results:
- PFGE successfully distinguished non-pathogenic strains from entomopathogenic ones.
- Twenty-one distinct SmaI restriction patterns (SRPs) were identified among the pathogenic strains.
- Serotype 5a5b strains showed identical SRPs, indicating a conserved clonal lineage (SRP 12).
- Most other serotypes were subdivided into multiple SRPs.
- Toxin synthesis correlated with specific SRPs in serotypes 2a2b, 3, and 6, linking chromosomal structure to pathogenicity.
Conclusions:
- PFGE provides a robust method for classifying Bacillus sphaericus strains.
- Genetic diversity exists within B. sphaericus serotypes, with some serotypes representing clonal lineages.
- Chromosomal structure, as revealed by PFGE, is associated with toxin production and pathogenicity in certain Bacillus sphaericus serotypes.