PCR-based identification of Bacillus thuringiensis isolated from soil samples in Nigeria

Area of Science:

• Microbiology
• Molecular Biology
• Entomology

Background:

• Bacillus thuringiensis (Bt) is a soil bacterium known for its insecticidal properties.
• Mosquito control is crucial for public health, and Bt isolates are promising biological agents.
• Accurate identification and characterization of Bt isolates are essential for effective application.

Purpose of the Study:

• To differentiate and characterize Bacillus thuringiensis isolates from soil samples using molecular techniques.
• To confirm the presence of delta-endotoxin genes responsible for insecticidal activity.
• To compare the efficacy of serological and PCR-based identification methods.

Main Methods:

• Isolation of Bacillus thuringiensis from soil samples.
• Serological identification of selected isolates.
• Polymerase Chain Reaction (PCR) amplification of delta-endotoxin (cry) genes.
• Analysis of PCR amplicon sizes for differentiation.

Main Results:

• Six Bacillus thuringiensis isolates toxic to mosquito larvae were identified.
• PCR analysis confirmed the presence of cryI a, b, c, or II genes in at least four isolates.
• No amplicons were detected for Cry IV A, B, and D genes in the tested isolates.
• One isolate identified by PCR remained unidentified by serological methods.

Conclusions:

• PCR-based techniques provide effective differentiation of Bacillus thuringiensis isolates.
• The presence of specific cry genes correlates with toxicity to mosquito larvae.
• Molecular methods offer complementary identification capabilities to traditional serological techniques.