Fig. 1
Induction of hok and its effect on cell survival in E. amylovora. a Expression levels of hok induced with four progressive doses (0.001 mM, 0.01 mM, 0.1 mM, and 1 mM) of isopropyl β-D-1-thiogalactopyranoside (IPTG) or with water. b The effect hok induction on survival rate of E. amylovora. The concentrations of IPTG supplemented are indicated in parentheses. After IPTG or water addition, cultures were incubated at 28 °C with 200 rpm shaking for 1 h. Expression levels of hok were measured using quantitative real-time PCR (qRT-PCR), and fold changes were calculated using the 2-ΔΔCT formula. The recA gene was used as an endogenous control. Survival rate was determined as the ratio of colony forming units (CFU)/ml in Ea1189(pOE-hok) after and before the addition of IPTG. Results represent the means of three replications, and error bars indicate the standard deviation. Different letters indicate significant differences (P < 0.05) using Tukey’s HSD (honestly significant difference) test. The experiments were conducted three times with similar results