[Factors increasing the effectiveness of Bacillus subtilis fusion].

The factors potentiating the efficacy of fusion of protoplasts of Bacillus subtilis were studied. A 50-fold increase in the yield of primary prototrophs was provided by 90-minute preincubation of protoplasts in a liquid hyperbaric medium and 10-minute treatment with trypsin. Increased efficacy of fusion of protoplasts depended on their regeneration percentage.

[Effect of B polA1- exrA- and recA-gene mutations on the reparation of single-strand DNA breaks induced by N-nitrosomethylurea].

The effect of different doses of N-methyl-N-nitrosourea (MNU) on a viability of bacterial cells with different defects in the systems of repair of UV-damages, and the MNU induction of single-strand DNA breaks (SS) were studied. The kinetics of both processes was investigated. There was a good correlation between the NMU sensitivity of bacterial cells and the number of SS in their DNAs.

[Intergeneric conjugational crossing of Escherichia coli with Salmonella typhimurium. II. Transfer of a polA1 mutation from Escherichia coli to Salmonella typhimurium and its phenotypic expression in the salmonella genome].

The Escherichia coli structural gene for DNA polymerase I was inserted into Salmonella typhimurium chromosome by conjugal transfer. The genetic analysis of P1-mediated transduction of obtained hybrid showed that polA gene is located in it between metE and rha loci and is cotransduced with metE (about 50%) and rha (12%). The phenotypic properties of polA1 hybrid E.

[Reparation of the damages induced by UV light in salmonellae].

The survival of Salmonella typhimurium wild type strains after UV-irradiation is studied. It is demonstrated that many of these are more sensitive to UV-irradiation than Escherichia coli of the wild type. Alkaline sucrose density gradient centrifugation has demonstrated a deficiency of these strains in normal excision repair of UV-damaged DNA.