Survival of exponential phase cells at 50°C and the effect of indole supplementation.

<p>(A) Exponential phase cultures of wild-type and <i>ΔtnaA</i> cells (OD₆₀₀≈0.1) were shifted from 37°C to a 50°C and % survival was measured after 2 h and 24 h. There is a significant difference between the survival of wild-type and <i>ΔtnaA</i> at 24 h (t-test: t = 2.3073, df = 12.374 [Welch’s correction], p = 0.0195). (B) To test the effect of indole supplementation, 20 μM indole (dissolved in DMSO) was added to a <i>ΔtnaA</i> culture. An appropriate amount of DMSO was added to the control cultures that lacked indole. All data are the average of at least 4 independent cultures. Error bars show standard deviations.