Survival of the S. thermophilus strain LMG18311 and the Δ rgg
mutant after heat shock (0, 15, 30, 45 and 60 min at 52°C). S. thermophilus was cultivated in CDM medium at 30°C and then exposed to heat stress. The percentage of survival was calculated as N/N0 ×100 where N0 is the CFU number of the control condition and N the CFU number in heat stress condition. Dark gray bars correspond to wild type strain and light gray bars correspond to Δrgg
strain. Data are presented as the mean +/- standard deviation of 3 independent experiments done in triplicate. Student's t test: *, p < 0.001.