[Fermentation of inositol by bacteria of the genus Salmonella]. / Fermentatsiia inozita bakteriiami roda Salmonella.

The capacity for the fermentation of inositol varies in different Salmonella strains. At the same time this capacity forms the basis for the determination of biovars (e. g., in S. typhimurium) and sometimes serves as the only sign for distinguishing different Salmonella sero- and biovars (e. g., S. mission and S. isangi, etc.). The study of the capacity of wild Salmonella strains for the fermentation of inositol has revealed that the fermentation of inositol is controlled by chromosomal and, seemingly, plasmid genes. In the latter case the possibility of using this sign for the biochemical and epidemiological typing of Salmonella strains is questionable.

[Detailed mapping of the Hly-region of the plasmid pHly241. Homology of the hemolysis determinants of plasmids pHly241 and pHly195]. / Detal'noe kartirovanie Hly-oblasti plazmidy pHly241. Gomologiia determinantov gemoliza plazmid pHly241 i pHly195.

Data on the hemolysin synthesis determined by the plasmid pHly241, belonging to the incompatibility group I2, and its derivatives are presented in this paper. The restriction analysis of the pHly241 plasmid has resulted in the detailed mapping of the hly determinant region in the plasmid. The substantial homology has been demonstrated between the regions of the plasmids pHly241 and pHly195 coding for hemolysin synthesis and excretion from the bacterial cell.

[Increased transformation ability of Escherichia coli strains carrying the plasmid pLD4]. / Povyshennaia sposobnost' k transformatsii shtammov kishechnoi palochki s plazmidoi pLD4.

The effect of resident plasmid pLD4, a derivative of plasmid Hly241, on transformability of the host bacteria cells has been studied. Plasmid pLD4 was transferred into the different strains of E. coli subsequently transformed by the DNA of plasmids pBR322, pBR325, pAL-R2, pMB9. The majority of strains harbouring pLD4 obtain the increased ability to be transformed as compared with the ability of isogenic plasmidless strains. The similar but less expressed effect was conferred by the plasmid Hly241. Another hemolytic plasmid Hly195 and its derivatives, carrying the different transposons, as well as plasmid F' tet Hly did not increase the transformability of host bacteria. The optimal parameters for transformation of the strains harbouring pLD4 and plasmidless strains coincide, but the number of competent cells is considerably higher for plasmid containing strains, due to preliminary results.

[Competence in Escherichia coli cells. V. Interaction of the competence factor with the cells]. / Kompetentnost' u kletok Escherichia coli. Soobshchenie V. Vzaimodeistvie faktora kompetentnosti s kletkami.

Some trends of the interaction of the competence factor with the cells are described on the model of phage lambda transfection. It is shown that this process depends on the composition of the recipients growth media, the temperature regime in the interaction processand on the concentration of the competence factor and the recipient cells. The preliminary treatment of the recipient by EDTA (0.0001 M), CaCl2 (less than 0.02 M), MgCl2 (less than 0.01 M), and NaCl (less than 0.01 M) resulted in the increaze of their sensitivity to subsequent treatment by the factor. Data are obtained demonstrating that after the treatment of cells by the competence factor their sensitivity to decreased CaCl2 concentration is increasing.

[Competency of Escherichia coli cells. IV. Effect of freezing--thawing on the formation of competency in Escherichia coli cells in the presence of Ca++ ions]. / Kompetentnost' u kletok Escherichia coli. Soobshchenie IV. Vliianie zamorazhivaniia--ottaivaniia na formirovanie kompetentnosti u kletok Escherichia coli v prisutstvii ionov Ca++

The paper is initiated in the aim to use the effect of freezing-thawing in the system of intact Escherichia coli cells treated with Ca++ ions to increase the transfection efficiency. It is demonstrated that freezing-thawing of Ca++ treated cells increases the transfection indices of lambda phage DNA for E. coli Hfr clone with low transfection indices in 20-30 times, and for the strain of E. coli X7026 of high competence-in 5 times. Freezing-thawing efficiently increased the transfection only in cells with a decreasing competence. E. coli Hfr H cells acquired the capacity of more efficient lambda phage DNA perception independently on the growth phase, while in E. coli X7026 cells the maximal transfection increase under the effect of complementary interactions was observed at the beginning of the logariphmic and stationary growth stages, but not during the competence period. Short-term changes emerging in cells during freezing-thawing can probably promote the better penetration of Ca++ ions to active sites on the cell surface, which produces favourable conditions for lambda phage DNA formation.

[Competence in Escherichia coli cells. III. Formation of competent states in Escherichia coli X7026 and Escherichia coli Hfr H cells during storage in different conditions]. / Kompetentnost' u kletok Escherichia coli. Soobshchenie III. Formirovanie kompetentnogo sostoianiia u kletok Escherichia coli X7026 i Escherichia coli Hfr H pri khranenii v razlichnykh usloviiakh

The competence formation in 2 strains of Escherichia coli X7026 and Hfr H to isolated phage gamma DNA after the prolonged treatment of cells with Ca++ ions at low temperatures was investigated. In both strains studied the sensitivity of cells to phage lambda DNA increased during several days of maintenance at 4 degrees C in 0.2 M CaCl2, and reached the maximal value in 24-48 hours for E. coli Hfr H cells, and in 72-96 hours for E. coli X7026 cells. Cells maintained in CaCl2 for 24 hours and more interacted more effectively with DNA in the cold, and didn't need Ca++ ions at the last stage of transfection (incubation of the infectious mixture at 37 degrees C) as the freshly grown cells did. Variations induced in the cells after the prolonged action Ca++ ions were preserved only in the presence of CaCl2. After the washing of CaCl2 from the cells with 0.15 M NaCl they returned to the initial state. The competence formation in cells of E. coli X7026 under the effect of Ca++ ions was going on more actively when the cells were preliminary incubated for several days at 4 degrees C in the absence of CaCl2. E. coli Hfr H cells were resistant to this treatment.