Bacillus thuringiensis protoxin: location of toxic border and requirement of non-toxic domain for high-level in vivo production of active toxin

Article Abstract:

A study of the position of the toxic border of Bacillus thuringiensis protoxin and the role of the non-toxic domain of the protein for active toxin production in vivo by introducing sequential termination codons reveals that mutations that code for the 606 aa and beyond are more toxic, while the mutations that code for 605 aa or less are non-toxic, indicating that the 606 position localizes the critical residue. Analysis of the toxicity of the extracts and the quantity of proteins in the immuno-precipitates indicates that the activity of the mutants is similar to that of the intact protein. Inclusion bodies formed from gene products of the intact protoxin are active and soluble in alkali, while such bodies from the mutants are inactive and insoluble.

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Involvement of chitinases of Bacillus thuringiensis during pathogenesis in insects

Article Abstract:

The chitinolytic activities of the chitinases of Bacillus thuringiensis during pathogenesis in insects were examined in two subspecies of B. thuringiensis against the larvae of Culicoides nubeculosus and against the caterpillars of the cotton leafworm. Results showed that the chitinase inhibitor allosamidin exhibited varying effects on the bacterial strains tested depending on the substrate used. It was also observed that the presence of Serratia marcescens chitinase A improves the activity of the two strains of B. thuringienses against hosts from different orders of insects.

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Bacillus thuringiensis subsp. aizawai generalized transducing phage phi-HD248: restriction site map and potential for fine-structure chromosomal mapping

Article Abstract:

The Bacillus thuringiensis subsp. aizawai transducing genome phi-HD248 is double-stranded and has a size of 47,150 bp. The restriction endonuclease map derived from the enzymes BamHI, BglII, SalI and SstI suggests a partial circular nature for the phage. The restriction fragments of BamHI, SstI and BglII have other full-length restriction fragments on either side. The terminal positions of BamHI, SstI and BglII fragments in all phi-HD248 DNA molecules are different. The enzyme SalI has a unique cleavage site which is probably useful as a vector for genes in B. thuringiensis.

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