Electrofusion of Escherichia coli cells.

Bacterial cell fusion was observed under conditions optimal for highly efficient electrotransformation of untreated Escherichia coli cells. E. coli clones possessing the joint phenotype were found after electric treatment of genetically marked parental strains. The phenotypes of the clones segregated due to a subsequent cultivation of the clones, whereas some of them turned out to be recombinants. Electron microscopy carried out 1 h after electric treatment of the cells revealed physical contacts between the cells being in parallel arrangement. The electrofusion processes detected are important for the estimation of electrotransformation efficiency. A possibility to use electrofusion of untreated bacterial cells for in vivo transfer of plasmid and chromosomal DNAs is discussed.