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S Cebrat

Publications and source records attributed to S Cebrat.

12 recordsLinked to original sources
PubMed1990

Conjugational cotransfer of IncFI and IncI conjugative plasmids forming aggregate in a pathogenic Citrobacter freundii strain.

Two plasmids, pEM4 (IncFI) determining virulence and pEM6 (IncI) determining colicine I production and resistance to tetracycline, have been found in a pathogenic strain of Citrobacter freundii. Even though pEM4 and pEM6 plasmids are conjugative and transfer themselves very efficiently during conjugation, a high cotransfer of both plasmids is observed--an unusually high fraction of transconjugants acquiring pEM6 acquires pEM4 and vice versa. The observed cotransfer of these plasmids is connected with their ability to complement their conjugational functions. An insertion mutant of pEM4 with decreased frequency of conjugational transfer has been isolated. This mutant (pEM44) lost its ability to mobilize nonconjugative plasmids. Its transfer is stimulated by pEM6 and it is transferred from (pEM44, pEM6) donors almost exclusively with pEM6 plasmid. The role of cotransfer and stimulation phenomena in spreading of plasmid aggregates in bacterial population is discussed.

Bacteriocin Plasmids↗
PubMed1989

Mobilization of R387 Inc K conjugative plasmid by the conjugative plasmid R64 Inc I.

Plasmid aggregate (R387, R64) was constructed in E. coli K12 strain. Plasmid R387 Inc K was stimulated to conjugational transfer by plasmid R64 Inc I. This stimulation was caused neither by recombination between both plasmids nor by trans-complementation of R387 conjugational systems by gene(s) product(s) of R64 plasmid. The observed phenomenon resembled rather mobilization of nonconjugative plasmids by conjugative ones. As in mobilization, the observed increase in R387 transfer frequency could take place only when both interacting plasmids were present in donor cells. Moreover, the entry exclusion system functioning in recipient cells, toward stimulating R64 plasmid affected strongly the conjugational transfer of stimulated R387 plasmid. Analogous phenomenon was observed during mobilization of nonconjugative plasmids by conjugative ones.

Citrobacter↗
PubMed1989

Genetic properties of plasmids isolated from pathogenic strain of Citrobacter freundii.

It was found that Citrobacter freundii SLJ10 strain was an etiological factor of swine diarrhoea in North Poland. This strain harboured a plasmid aggregate consisting of two plasmids-pEM4 responsible for virulence and pEM6 for selective advantage of the strain, determining resistance to tetracycline and production of bacteriocin. These two plasmids cooperated in conjugal transfer and formed an infective block of genetic information, which could be transferred to other strains of Enterobacteriaceae and cause their virulence.

Citrobacter↗
PubMed1987

R factors of pathogenic strains of Escherichia coli isolated from infant diarrhoea.

Several drug resistance patterns were determined in 170 pathogenic strains of E. coli isolated in 6 Polish towns from infant diarrhoea. The most frequent were strains resistant to 5 different drugs: ampicillin, tetracycline, chloramphenicol, streptomycin and sulfonamide. Conjugative R factors of 30 strains of the same resistance pattern (Ap Tc Cm Sm Su) were characterised by determining their Fi(F) character, incompatibility and molecular weight.

Anti-Bacterial Agents↗
PubMed1979

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate. IV. Reconstruction in R404 plasmid aggregate and separation of twelve genetically distinct derivative forms.

R404 plasmid aggregate is composed of two conjugative and two nonconjugative plasmids. Plasmid aggregate reconstructed from separated plasmids had the same genetic properties as the original R404 plasmid aggregate. It was found that plasmids of R404 factor could be transferred in conjugation in twelve different sets. These twelve genetically distinct classes of transconjugants formed only six groups differing in phenotypic characters.

Conjugation, Genetic↗
PubMed1978

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate. II. Separation of plasmids by transformation.

Transformational separation of plasmids from R404 plasmid aggregate found in Salmonella enteritidis strain was performed. Three classes of transformants differing in their resistance patterns were isolated. Genetic properties of the transformants suggest that their resistance is determined by single plasmids. Plasmid pCK3 (Tra-ApCbCrSuSm) and pCK4 (Tra-ApCbCrCm) are nonconjugative while plasmid pCG1 (TraApCbCrSuSmTcKmNm) is conjugative. Separation of all plasmids of R404 plasmid aggregate allowed to determine their genetic properties and the manner of conjugational transfer of R404 plasmid aggregate R-determinants.

Anti-Bacterial Agents↗
PubMed1978

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate. III. Entry exclusion features of its separative forms.

The genetic relationship of four plasmids separated from R404 plasmid aggregate has been characterized by investigating entry exclusion and intracellular incompatibility. It has been found that the four plasmids exist in an autonomous state in cells carrying the aggregate. They are compatible and the two conjugative plasmids possess different traS genes.

Anti-Bacterial Agents↗
PubMed1977

Genetic properties of the Salmonella enteritidis R404 plasmid aggregate I. Conjugational separation of different derivative plasmid aggregates and their genetic properties.

Conjugational transfer of R404 factor, found in Salmonella enteritidis strain, was examined. Six derivative forms differing in resistance pattern were isolated. The manner of conjugational separation during transfer of R404 factor from E. coli to E. coli strain was the same as from the original strain of S. enteritidis to E. coli strain. During following conjugation, all isolated forms except one, could give forms differing in a resistance pattern from the parenteral ones. This one form, from which different conjugational forms could not be separated, was assumed to be a single plasmid and was designated pCK2. All other forms, including the original R404 factor were assumed to be plasmid aggregates.

Conjugation, Genetic↗
PubMed1976

Transformation of Escherichia coli by R404 factor DNA and properties of the transformants.

Three r-determinants (Cb Cm Cf) out of eight present in R404 factor were transferred in transformation of Escherichia coli by the plasmid DNA isolated from minicells. The r-determinants acquired in this way formed the replicon tr404-1 and were untransferable by conjugation unless another self-transmissible plasmid was present in recipient. The evidences are presented in support of hypothesis that the transfer events consist in infection of transformant cells with sex factor, recombination between tr404-1 replicon and the sex factor and finally transfer of the new formed structure to the host cells of the sex factor.

Anti-Bacterial Agents↗