Fig. 1.

Recovery of S. mutans from stress. To test the contribution of endogenous CSP to stress recovery, early-log phase cells of the UA159 wild-type, a ΔcomC mutant (no CSP production) and an ΔcomC complemented strain (overproduction of CSP) were grown in THYE (control), in THYE containing spectinomycin (A) or in THYE at pH 5.0 (B) for 2.5 h. Cells were harvested and resuspended in fresh THYE at 1/100 dilution. Absorbance of the growing cultures was then automatically recorded for 16 h. Cells that recovered from stress in the absence of CSP showed a growth defect, while the CSP overproducing cells recovered from stress more quickly but attained lower growth yields than the wild type. These results imply that the S. mutans CSP pheromone is important in the stress response to acid and the antibiotic spectinomycin.