TABLE 1.

Bacterial strains used

Strain	Relevant characteristicsa	Source
Streptococcus sanguinis SK36		42
Streptococcus gordonii DL1		43
Streptococcus mutans UA159		44
Streptococcus oralis J22		45
S. sanguinis ΔlytF	ssa_0036 deleted by replacement with ermAM; Ermr	This study
S. sanguinis lytF-c	ΔlytF with pDL278/ssa_0036, transformed via concatenation; Ermr, Spcr	This study

^aErm, erythromycin; Spc, spectinomycin.