[Acceptance and transfer of plasmid Rts1 by bacteria of the genus Erwinia]. / Vospriiatie i peredacha plazmidy Rts1 bakteriiami roda Erwinia.

The ability of 13 Erwinia strains to accept, to inherit and to transmit the Rts1 factor by conjugation was studied. 11 strains accepted the Rts1 factor from Escherichia coli K-12 CSH-2 with the frequency of about 10(-7)--10(-3). The Rts1 factor was genetically stable in the Erwinia cells and was not eliminated by acriflavine and under the temperature of 37 and 42 degrees C. All the R+ exconjugants were characterized with more high degree of the resistance of kanamycin than E. coli cells harbouring the same R factor. Erwinia strains harbouring the Rts1 plasmid transferred it by conjugation into homologic (Erwinia) and heterologic (E. coli) bacteria. The study of kinetics of the transfer of the Rts1 factor in different mating systems showed that the transfer of this plasmid from R+ Erwinia into R- Erwinia and R- E. coli--in the liquid medium. It is concluded that Erwinia can be the host and the donor of the Rts1 factor.

[Bacteriocinogenic activity of strains of the genus Erwinia]. / Bakteriotsinogennaia aktivnost' shtammov roda Erwinia.

Antibacterial activity of 272 Erwinia strains was studied. It was found that 182 or 66.9 per cent of the strains were capable of producing spontaneously antibacterial substances belonging to the class of bacteriocins; 125 bacteriocynogenic strains were divided into 25 groups on the basis of their antibacterial spectrum similarity; 57 bacteriocynogenic strains were not included into any of these groups because of their significant heterogenicity with respect to the feature studied. It was shown that most of the strains inhibited viability of the bacteria of both its own and other species. Investigation of the antagonistic activity of the Erwinia strains with broad antibacterial spectra with respect to E. coli indicative for colicins gave negative results. The study of the Erwinia strains sensitivity to the antibacterial effect of the bacteriocynogenic cultures showed that 210 out of 272 cultures were sensitive to separate bacteriocins.

[Characteristics of the conjugation transfer of the R plasmids in bacteria of the intestinal group to Erwinia cells]. / Osobennosti kon''iugatsionnoi peredachi R-plazmid bakterii kishechnoi gruppy kletkam Erwinia.

The conjugal transfer of seven R factors with different genes of drug resistance from Escherichia coli bacteria to twenty Erwinia strains was studied. Seven Erwinia strains were able to accept R plasmids, however the frequency of R factors transfer from E. coli to Erwinia was about 10(-6)-10(-4), and as a rule was higher when the cross was made at optimum temperature for the donor. The most of R- exconjugants showed higher degree of resistance to streptomycin and lower degrees of resistance to tetracycline and chloramphenicol than donor E. coli strains. R plasmids which were transferred to Erwinia from enteric bacteria were characterized by low genetical stability and in some cases were eliminated at first generations of recipient bacteria. Some R- strains of Erwinia exconjugants were able to transfer the accepted plasmids by conjugation into E. coli cells, but were not able to do it in homologous systems.

[Study of the drug resistance of bacteria of the genus Erwinia]. / Izuchenie lekarstvennoi ustoichivosti bakterii roda Erwinia.

Sensitivity of 788 strains of Erwinia isolated from natural substrates and received from other laboratories was studied with respect to penicillin, streptomycin, tetracycline, chloramphenicol and kanamycin. It was found that 346 (43.9 per cent) strains were drug resistant. However, the levels of the resistance to most of the drugs tested were not high and amounted to 5-10 gamma/ml. Penicillin resistance was the most frequent characteristics of the strains studied (341 strains). The resistance levels to this drug were higher than those to the other drugs and ranged from 25 to 100 gamma/ml. In some cases they were higher. Analysis of the drug resistance spectra showed that Erwinia strains resistant to 1 (172 strains) or 2 (149 strains) antibiotics were most frequent. 25 strains were multiresistant (to 3-5 drugs). All the resistant strains had 18 types of drug resistance. The genetic control of the drug resistance feature was carried out in the experiments on crossing of the drug resistant strains of Erwinia with the sensitive bacteria of the same genera, i.e. Erwinia chrysanthemi EP-3 and E. coli K-12. The results of the experiments were negative, which should be considered as an evidence of chromosomal localization of the antibiotic resistant genes in the Erwinia bacteria studied.

[Compatibility of R-factors in naturally occurring enteric bacteria]. / Izuchenie sovmestimosti R-faktorov u kishechnykh bakterii, vydelennykh iz prirody

The compatibility of four wild type fi+R factors to R1 factor, a representative of the FII compatibility group of F-like class of the plasmids was studied. Two of them (R448 and R459) were incompatible to the R1 factor at selective for R448 and R459 donors conditions. The recipient R1 factor elimination apparently takes place at the first generations of conjugants. The compatibility of these R plasmids to R1 is possible at selective for donor and recipient plasmids conditions. R459 and R1 factors were transfered to Escherichia coli W945 simultaneously and recombination between them was suggested. B211 and R215 factors are compatible to R1 factor and their coexistence with the last is stable despite whether conjugants were selected on one or two R plasmids principle. Further conjugants transfer R211 and R215 only, but not R1. It is concluded that R factors No 448 and No 459 are of FII group compatibility. R211 and R215 factors group compatibility is still unknown.