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Haemolytic activity associated with parasporal inclusion proteins of mosquito-specific Bacillus thuringiensis soil
1Institute of Biological Control, Faculty of Agriculture, Kyushu University, Fukuoka, Japan.
Abstract:
Solubilized parasporal inclusions of the three mosquito-specific Bacillus thuringiensis isolates belonging to three different H serovars, co-isolated from a single soil microhabitat, showed haemolytic activity towards mammalian erythrocytes. Neutralization tests with antibodies against whole inclusion proteins resulted in crossed neutralization of haemolytic activity among the isolates and the type strain of B. thuringiensis serovar kyushuensis, indicating that the three soil isolates produce toxins related to the CytB toxin. No cross-neutralization occurred between the type strain of B. thuringiensis serovar israelensis and the three soil isolates.
Insights
Three mosquito-specific Bacillus thuringiensis soil isolates exhibit hemolytic activity. Their toxins are related to CytB, showing cross-neutralization with B. thuringiensis serovar kyushuensis but not B. thuringiensis serovar israelensis.
Area of Science:
- Microbiology
- Insect Toxicology
- Biochemistry
Background:
- Mosquito-specific Bacillus thuringiensis (Bt) isolates are crucial for insect biological control.
- Parasporal inclusions contain insecticidal crystal (Cry) proteins and other toxins.
- Understanding toxin diversity in soil-isolated Bt strains is important for effective pest management.
Purpose of the Study:
- To investigate the hemolytic activity and toxin profiles of three novel mosquito-specific Bacillus thuringiensis isolates.
- To determine the relationship between the toxins produced by these isolates and known Bt toxins, specifically CytB.
Main Methods:
- Solubilization of parasporal inclusions from three Bt isolates.
- Assay of hemolytic activity against mammalian erythrocytes.
- Neutralization tests using antibodies against whole inclusion proteins and specific type strains (B. thuringiensis serovar kyushuensis and B. thuringiensis serovar israelensis).
Main Results:
- All three mosquito-specific Bt isolates demonstrated hemolytic activity against mammalian erythrocytes.
- Antibody neutralization tests indicated that the hemolytic toxins are related to CytB.
- Cross-neutralization was observed between the soil isolates and B. thuringiensis serovar kyushuensis type strain, but not with B. thuringiensis serovar israelensis type strain.
Conclusions:
- The studied mosquito-specific Bt isolates produce CytB-related toxins responsible for hemolytic activity.
- These findings contribute to the characterization of Bt toxins and their potential applications in mosquito control.
- The distinct neutralization patterns highlight serovar-specific toxin variations within Bacillus thuringiensis.