A mosquitocidal toxin gene, cloned from Bacillus thuringiensis subsp. israelensis, was introduced into mutant crystal-negative B. thuringiensis subsp. israelensis cells. Partial toxicity to mosquitos was restored. The 58-kilodalton cloned gene product is a minor protein component of B. thuringiensis subsp. israelensis crystals and is structurally related to a major, 135-kilodalton crystal toxin.

Spores of Bacillus thuringiensis subsp. israelensis and their toxic crystals are bioencapsulated in the protozoan Tetrahymena pyriformis, in which the toxin remains stable. Each T. pyriformis cell concentrates the spores and crystals in its food vacuoles, thus delivering them to mosquito larvae, which rapidly die. Vacuoles containing undigested material are later excreted from the cells. The fa...

Electron microscopy of Bacillus thuringiensis subsp. kyushuensis revealed that the parasporal inclusions are composed of a homogeneous center surrounded by a thick, electron-dense coating. Antibodies directed against the 135- and 65-kilodalton B. thuringiensis subsp. israelensis peptides cross-reacted with the 70- and 26-kilodalton peptides, respectively, of B. thuringiensis subsp. kyushuensis.

Bacillus thuringiensis subsp. israelensis produces a potent mosquitocidal protein, Cry4A. We have identified a 15-bp catabolite responsive element (cre), overlapping the -35 element of the cry4A promoter. Changing a guanine to adenine at position -49 in the promoter abolished glucose catabolite repression of cry4A and enhanced promoter activity two- to threefold. This cis regulatory element is ...

A novel mosquitocidal bacterium, Bacillus thuringiensis subsp. jegathesan, and one of its toxins, Cry11B, in a recombinant B. thuringiensis strain were evaluated for cross-resistance with strains of the mosquito Culex quinquefasciatus that are resistant to single and multiple toxins of Bacillus thuringiensis subsp. israelensis. The levels of cross-resistance (resistance ratios [RR]) at concentr...

An enzyme-linked immunosorbent assay was used to detect and quantitate the parasporal crystal toxins of Bacillus thuringiensis subspp. kurstaki and israelensis. The assay method described is extremely sensitive, accurate, and highly specific. With this technique, crystalline insecticidal proteins from several subspecies of B. thuringiensis were compared. The dipteran crystal toxin produced by B...

The DNA regions upstream from the genes encoding polypeptides of Bacillus thuringiensis subsp. israelensis larvicidal crystals (cry4A, cry4B, cry11A) contain sequences with similarities to the spo0A box of Bacillus subtilis (or '0A' box) and the promoter recognized by the sigma H-associated RNA polymerase of B. subtilis. Expression of cry-lacZ transcriptional fusions was analysed in various B. ...

The crystal delta-endotoxin of Bacillus thuringiensis subsp. israelensis is less toxic to larvae of Anopheles freeborni than to larvae of Aedes aegypti. However, when solubilized crystal was used, larvae from both species showed similar sensitivities. This effect presumably was due to the differences in feeding behavior between the two mosquito larvae when crystal preparations are used. A proce...

Vegetative Bacillus thuringiensis subsp. israelensis cells (6 X 10(5)/ml) achieved 100% mortality of Aedes aegypti larvae within 24 h. This larvicidal potential was localized within the cells; the cell-free supernatants did not kill mosquito larvae. However, they did contain a heat-labile hemolysin which was immunologically distinct from the general cytolytic (hemolytic) factor released during ...

Three species of Bacillus were evaluated as potential surrogates for Bacillus anthracis for determining the sporicidal activity of chlorination as commonly used in drinking water treatment. Spores of Bacillus thuringiensis subsp. israelensis were found to be an appropriate surrogate for spores of B. anthracis for use in chlorine inactivation studies.