Validity of mechanism of gene transfer in the process called conjugation in bacteria.

ABSTRACT

We have attempted a new evaluation of the process of conjugation in bacteria, because of some basic dissimilarities observed between this and that of eukaryotes, or plants and animals. Reference donor and recipient strains, widely used to prove conjugation in bacteria, were chosen; addition of DNase during the conjugation process, led to an unexpected but highly reproducible increase in the transconjugant colony counts (TCC; ca. > or = 1 log), when compared with that of the controls without DNase. Transconjugants were also obtained when the same live donors were substituted with the UV-killed ones although the TCC was very low initially. Contrarily, donors treated with DNA-intercalating agents, e.g. acridine orange or ethidium bromide, resulted in a complete failure to produce transconjugants. There was a quantitative relationship between the DNase used on donors and levels of DNA sugars/nucleotides/DNA, which possibly resulted from interaction between the DNase and DNA being present/produced on the donor surface. This may be indicative of what may actually happen in the donor-recipient mixtures in the conjugation test proper, where the recipient DNase may activate a donor DNA production cycle. The evidences presented did not suggest that the donor DNA in the conjugation process is actually vestibuled through any intercellular conjugation passages, and is susceptible to the action of DNase or the intercalating dyes.