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Growth & toxicity of Bacillus thuringiensis var israelensis

S Y Desai, Y I Shethna

    The Indian Journal of Medical Research
    |September 1, 1989
    PubMed

    Insights

    Bacillus thuringiensis var israelensis grew well and sporulated in chemically defined media with specific amino acids. Formulations showed high toxicity against mosquito larvae for extended periods.

    Area of Science:

    • Microbiology
    • Insect Toxicology
    • Biotechnology

    Background:

    • Bacillus thuringiensis var israelensis (Bti) is a potent microbial larvicide.
    • Optimizing Bti production and formulation is crucial for effective pest control.

    Purpose of the Study:

    • To evaluate chemically defined media for Bti growth and sporulation.
    • To assess the larvicidal efficacy of Bti and its immobilized formulations against Culex pipiens quinquefasciatus.

    Main Methods:

    • Culturing Bti in media with glutamic acid, glutamine, or aspartic acid (20 mM).
    • Analyzing parasporal crystal production and toxicity.
    • Testing immobilized Bti formulations (calcium alginate, agar agar) against mosquito larvae.

    Main Results:

    • Chemically defined media with individual amino acids supported abundant Bti growth and sporulation.
    • Glutamine (20 mM) accelerated sporulation, yielding an LC50 of 3.92 µg/L against C. pipiens quinquefasciatus.
    • Immobilized Bti formulations maintained >90% toxicity for 90 days.

    Conclusions:

    • Chemically defined media are suitable for Bti production.
    • Glutamine enhances Bti sporulation and larvicidal activity.
    • Immobilized Bti formulations offer long-lasting mosquito control.

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