TABLE 2.

Effects of heat and DNA damage stresses on lexA (SMU.2027) gene expression

Stress	Change in S. mutansa
	WT	ΔlexA::lexA A115D mutant	ΔclpP mutant
50°C	+2.84 ± 0.55	+1.18 ± 0.17*	−1.31 ± 0.14*
Antibiotic ofloxacin	+5.22 ± 3.03	+1.09 ± 0.11*	+1.29 ± 0.45*
Hydrogen peroxide	+5.04 ± 3.93	+1.32 ± 0.25*	+1.28 ± 0.54*

^aqPCR was performed to analyze lexA gene expression. The expression is presented as the average fold change ± standard deviation compared with lexA gene expression in the absence of stress. Statistical significance was determined by using Student's t test with the parametric P value cutoff set at <0.01 (*, mutant versus WT).