A direct transfer of plasmid pBP517 from C600 to J53 Escherichia coli K12 strains by electroporation, either by the standard method, or in the presence of 20 μg/mL of DNAse was carried out. In a standard experiment, donor and recipient bacteria were mixed and subjected to the electroporation procedure, about 2700 (range 1600-3700) recombinants were found, while no colonies were detected from non treated bacteria. When the same tests were performed at the presence of DNAse the number of recombinants fell to about 200 (range 183-218). This difference between the number of colonies found in the presence or in absence of DNAse was observed every time the tests were repeated. According to these observations, plasmid DNA has been transferred from donor to recipient cells via electroporation also when DNAse was added. Since the free genetic material is destroyed by the enzyme and recombination takes place it has been hypothesized that there must be a direct contact between the partner cells.
contact between bacterial cells, electroporation, direct DNA transfer