[Characterization of crystal-forming bacteria Bacillus thuringiensis subsp. tohokuensis toxic to mosquitos].

Distribution study of Bacillus thuringiensis strains in Western Siberian soils allowed us to isolate crystal-forming bacteria assigned to a new pathovar of Bacillus thuringiensis ssp. tohokuensis with a toxic effect on mosquito larvae. A description of this bacterial pathovar is presented.

[Entomopathogenic bacteria Bacillus thuringiensis as producers of restriction endonucleases]. / Entomopatogennye bakterii Bacillus thuringiensis--produtsenty éndonukleaz restriktsii.

A total of 115 collection strains of Bacillus thuringiensis, belonging to various subspecies, have been studied for the presence of DNA restriction-modification systems. Restriction endonucleases of 13 strains have been isolated and characterized. No considerable correlations between the taxonomic positions of the bacteria and the specificities of the endonucleases isolated have been detected. It is concluded that the enzymes with identical specificities are present in both the crystalliferous and acrystalliferous strains of the same subspecies.

[Identification and characterization of strains of Bacillus thuringiensis by genomic fingerprinting using biotinylated phage M13 DNA]. / Identifikatsiia i pasportizatsiia shtammov Bacillus thuringiensis metodom genomnoi daktiloskopii s ispol'zovaniem biotinilirovannoi DNK faga M13]

Genomic DNA of the entomopathogenic bacterium Bacillus thuringiensis was analyzed by the genomic fingerprinting technique. The biotin-labeled single-stranded DNA of the phage M13 was used as a marker of hypervariable sequences. A procedure for analyzing the differentiation among various Bacillus thuringiensis strains was developed. Characteristic patterns of fingerprints were obtained for several strains, the main representatives of subspecies that are most frequently used in the manufacture of bacterial insecticides, such as subsp. thuringiensis, subsp. kurstaki, and subsp. galleriae. Because no essential differences were revealed in band patterns upon comparing fingerprints of crystal-producing bacterial strains with those of acrystallic mutants, it was assumed that the loss of crystal-producing ability in the insect pathogen Bacillus thuringiensis is not connected with significant rearrangement of its genome.

[Comparative characteristics of mutants of Bacillus thuringiensis subsp. Kurstaki]. / Sravnitel'naia kharakteristika mutantov Bacillus thuringiensis subsp. Kurstaki.

A study of physiological and biochemical properties of 12 strains of Bacillus thuringiensis subsp. kurstaki was performed. The strains studied included natural isolates similar to the type strain in their properties, a Cry-Spo+ mutant, and also mutants assigned to C-1 or C-73 crystovar according to the properties of their parasporal crystals and the ability to hydrolyze esculin, generate acid from salicin, and exert urease activity. The crystals produced by C-1 crystovar cultures were three times larger than those formed by C-73 crystovar bacteria; their distinctive feature was pathogenicity for mosquito larvae, and their effect on other insects (gypsy moth and meadow moth) was on the average twofold greater than the effect of C-73 crystovar crystals. A study of the antibacterial action of delta-endotoxins of B. thuringiensis subsp. kurstaki allowed us to more clearly elucidate the reasons for the differences in biological activity of C-1 and C-73 crystovars. Comparative analysis of the data obtained confirmed that the effect of delta-endotoxins, formed per unit volume of the culture liquid, on insects and microorganisms is an important characteristic of B. thuringiensis strains. Of all the strains studied, the Cry-Spo+ mutant was the most potent producer of proteases and lecithinase.