Effect of saeRS deletion on Triton X-100-induced autolysis. SE1457ΔsaeRS, SE1457, and SE1457saec cells were diluted in TSB medium containing 1 M NaCl, grown to mid-exponential phase (OD600 = ~0.6-0.8), and resuspended in the same volume of 0.05 M Tris-HCl solution containing 0.05% Triton X-100 (pH 7.2). OD600 readings were measured every 30 min. The autolysis rate induced by Triton X-100 was calculated as follows: lysis rate = OD0 - ODt/OD0. The experiments were carried out in triplicate independently. WT, SE1457; SAE, SE1457ΔsaeRS; SAEC, SE1457saec.