"Conjugal" transfer of plasmid DNA among oral streptococci.

Abstract

The .beta. plasmid from Streptococcus faecalis strain DS5, which codes for resistance to erythromycin and lincomycin, was introduced into a Lancefield group F streptococcus, strain DR1501, by transformation. This strain, DR1501 (.beta.), was an excellent donor of the .beta. plasmid and readily transferred the resistance markers to various lactic acid bacteria, including certain strains of S. mutans, S. sanguis and S. salivarius. The transfer of the .beta. plasmid is mediated by a mechanism that requires cell-to-cell contact. The transfer of plasmid RNA during conjugation was confirmed by the isolation of .beta. plasmid from transconjugant clones and by their ability to then serve as donors of the erythromycin and lincomycin resistance markers.