RESUMO
It was shown that among intergeneric conjugants of Vibrio cholerae biotype proteus (a donor) X Serratia marcescens (a recipient), growing in a medium with two antibiotics, most of the clones are similar, in their sensitivity to gamma-radiation, to the recipient or only differ in their higher radioresistance. There are some clones with higher radiosensitivity.
Assuntos
Serratia marcescens/efeitos da radiação , Vibrio cholerae/efeitos da radiação , Conjugação Genética/efeitos da radiação , Raios gama , Plasmídeos/efeitos da radiaçãoRESUMO
Intergeneric conjugants were obtained in crosses of bacteria Vibrio cholerae biotype proteus (donor) x Serratia marcescens. The study of exconjugants demonstrates the following characteristics: 1. The majority of clones isolated possess some morphological characters of the donor (colourlessness and transparency of colonies) which gradually disappear during successive transfers and return to the phenotype of recipients (red colour of colonies); 2. Exconjugants acquire a plasmid factor of the fertility of vibrios (P-factor) and may transmit it to other cells; 3. The majority of exconjugants are agglutinated by immune sera of both donor and recipient; 4. The factor of streptomycine resistance is transmitted from the donor to a recipient. Conjugants acquire streptomycine resistance from the donor and laevomycetine (chloramphenicol) resistance from the recipient and can grow on a nutrient medium containing both antibiotics; 5. The conjugants isolated show a great diversity in a number of characters and, supposedly, form a genetically heterogenous group. A great part of exconjugants is characterized by a slow growth, some of them being not viable and unable to survive during transfers. In connection with instability of conjugants, we suppose that the exongenome is not incorporated into the chromosome of the recipient; more likely, it exists in a form of self-replicating duplex, or is connected with a plasmid genome.
