[Characterization of a new strain of Bacillus thuringiensis, a producer of an endotoxin against coleoptera]. / Kharakteristika novogo shtamma Bacillus thuringiensis, produtsenta éndotoksina protiv zhestkokrylykh.

A new strain of Bacillus thuringiensis 2-7 was found to belong to the serotype H8. Cells of this strain contained irregular and flat crystalline inclusions and two large plasmids. The gene responsible for crystal formation is most likely located on the large plasmid greater than 105 MDa in size. Comparison of the cry gene of B. thuringiensis 2-7 and the cryIIIA gene of B. thuringiensis subsp. tenebrionis showed that their nucleotide sequences are identical.

[Comparative electron microscopic study of Bacillus thuringiensis cells grown in a chemostat]. / Sravnitel'noe élektronno-mikroskopicheskoe issledovanie kletok Bacillus thuringiensis, vyrashchennykh v khemostate.

It has been shown that the culture of Bacillus thuringiensis subsp. gall. 69-6 dissociates into R- and S-variants in chemostat. Although under some conditions the sporogenesis and the synthesis of S-variant toxin began two hours earlier than these processes in R-variant cells which were observed, respectively, after 10 or 12 hours from the beginning of the experiment, the intensities of sporogenesis and toxin production as well as the exit of spores and toxin excretion from cells were similar after 24 hours. The resistance to the bacteriophage present in chemostat was the advantage of S-variant cells. The data obtained by electron microscopy indicate that the phagoresistance is caused by the structural organization of the S-variant cell wall. Its peptidoglycan component is thin and is distinguished by crumb structure. By means of negative contrast microscopy it was found that the surface T-layer of R-variant cell wall was characterized by the tetragonal packaging of protein subunits indicating the regular orientation of phagoreceptors in it. The redistribution of protein subunits in the T-layer of S-variant cell wall prevented from the adsorbance of bacteriophages on the cell surface. The adsorbance of phages on the surface of R-variant cells was observed rather often. It led to the degradation of peptidoglycan, the formation of protoplasts and lysis.

[Biological characteristics of the variants of Bacillus thuringiensis subsp. galleriae formed during continuous culture]. / O nekotorykh biologicheskikh osobennostiakh variantov Bacillus thuringiensis subsp. galleriae, obrazuiushchikhsia pri nepreryvnom kul'tivirovanii.

Bacillus thuringiensis subsp. galleriae S. variants formed during continuous cultivation differ from the parent culture in certain properties. In contrast to the parent R form, their growth in the chemostat does not yield virulent mutants which can cause their lysis on solid media. The chemostat S forms are resistant against virulent phage mutants produced when the R variants are grown under the conditions of continuous cultivation and against a virulent phage obtained from the parent culture 69-6 under the action of vancomycin. The R forms are sensitive to these phages. When the S forms are grown under the chemostat conditions, they do not revert to the R forms. The R and S forms do not differ noticeably in the character of their growth, formation of spores and crystals, and biological activity.

[Variability of Bacillus thuringiensis under various growth conditions]. / Izmenchivost' Bacillus thuringiensis pri raznykh usloviiakh vyrashchivaniia.

When a lysogenic culture of Bacillus thuringiensis subsp. galleriae 69-6 was grown under the batch conditions, 93-99% of cells in the population produced R-form colonies and ca. 1% yielded S-form colonies. The amount of spore-forming cells was 99% in R-variants and 8% in S-variants. The quantity of S-variants rose abruptly to 99% when the culture was grown under the chemostat conditions. The number of S-variants increased with the rate and the duration of growth. The process was influenced by growth-limiting factors. Temperate phage variants capable of host culture lysis on solid media (i.e. h-mutants) were not found under the conditions of batch cultivation. However, such phage particles (h-mutants) appeared under the conditions of chemostat. The titre of these phage particles reached 10(8), 10(7) and 10(4) particles per 1 ml at limitation with yeast extract, glucose and phosphorus, respectively. Under the conditions of chemostat, the particles behaved as temperate ones and their growth was not found. Irrespective of the limitation, the phage titre did not correlate with the ratio of R and S-forms in the population. When the growth was limited with phosphorus, the quantity of S-forms increased abruptly while the spontaneous induction of the phage was inhibited. The quantity of cells capable of spore formation decreased in the cultures isolated from the chemostat and grown on MPA: 69-80% of the cells in R-forms and merely 8% in S-forms.

[Polylysogeny in Bacillus thuringiensis var. Galleriae cultures]. / O polilizogenii kul'tur Bacillus thuringiensis var. galleriae.

The culture of Bacillus thuringiensis var. galleriae was shown to be polylysogenic. As has been found earlier, the culture has a phage with the original structure of particles whose tail possesses a special substructure called a "collar". The phage was described in detail as a phage of Bac. thuringiensis 1-97 with a "collar". Further studies of the culture of Bac. thuringiensis var. galleriae 1-97 has shown that it also contains another phage which differs sharply from the first one in the morphology of particles, the spectrum of lytic action, and other properties. Electron microscopy of the cultural fluid of the Bac. thuringiensis var. galleriae cultures has revealed in them the presence of different amounts of the particles of both morphological types found in the strain 1-97. These data suggest that the cultures of Bac. thuringiensis var. galleriae are polylysogenic. The methods for the isolation of the new phage are described.

[Specific phages used for differentiation of the entomopathogenic bacterium Bacillus thuringiensis]. / O primeneii spetsifichnykh fagov dlia differentsiatsii entomopatogennykh bakterii, otnosiashchikhsia k Bacillus thuringiensis

The sensitivity to specific phages and morphological, physiological, and antigenic properties were compared among several strains of Bacillus thuringiensis isolated from insects inhabiting various geographical zones. All 43 cultures assigned to Bac. thuringiensis var. sotto and 198 among 170 cultures classed as Bac. thuringiensis var. dendrolimus were found to belong to Bac. thuringiensis var. dendrolimus. None of these cultures was resistant to its specific phage. The same was true of 22 studied cultures of Bac. thuringiensis var. galleriae. Only two among studied 45 cultures of Bac. thuringiensis var. thuringiensis were resistant to phages specific for this variety. Therefore, the abundance of variants resistant to specific phages in natural conditions differs among the varieties of Bac. thuringiensis. In most cases, cultures of the same variety of Bac. thuringiensis isolated from various insects inhabiting different geographical zones are identical by their sensitivity to specific phages and by other important characteristics.