1% survival for those shifted directly from 37°C to 50°C (Figure 2C). RB50ΔsigE pre-adapted at 40°C also survived better at 50°C than when directly shifted from 37°C to 50°C. However, only 38% of the RB50ΔsigE cells survived after one hour (compared to 76% of the wild-type RB50), and 5% survived after two hours at 50°C (Figure 2C). These results demonstrate that B.

selleck bronchiseptica exhibits a classical thermotolerance response and that SigE contributes to this response. Both ethanol and heat shock lead to protein unfolding and membrane perturbation and often elicit similar stress responses [43]. To test the role of sigE in response to ethanol stress, RB50 and RB50ΔsigE www.selleckchem.com/products/gsk2126458.html were subcultured from mid-exponential-phase cultures into fresh Stainer-Scholte Vistusertib research buy broth with or without 3% ethanol. Both strains grew similarly in medium without ethanol, as noted above. RB50 grew significantly slower in medium containing 3% ethanol than in medium without ethanol (compare the growth curve for RB50 in Figure 2D with that in Figure 2A), but eventually reached a cell density only slightly below that of cultures grown without ethanol. In contrast, the cell density of RB50ΔsigE grown in the presence of 3% ethanol never surpassed an OD600 of around 0.1, even after 24 hours. Expression of plasmid-encoded sigE in RB50ΔsigE complemented this phenotype, restoring growth in medium with 3%

ethanol to nearly that of RB50 (Figure 2D), indicating that sigE is required for survival during ethanol stress. Figure 3 Colonization of the respiratory tract of C57BL/6

mice by RB50 and RB50Δ sigE. Groups of three 4–6 week-old C57BL/6 mice were inoculated with 5 × 105 CFU of RB50 (filled squares) and RB50ΔsigE (open triangles). Groups of three mice were sacrificed at each time point. The bacterial load in the indicated organ is expressed as log10 CFU ± SE. The dashed line indicates the limit of detection. The experiment was performed twice with similar results and a representative dataset is shown. σE homologues Leukocyte receptor tyrosine kinase have also been found to play a role during oxidative stress in S. Typhimurium and Burkholderia pseudomallei[29, 41]. However, in disk diffusion assays, SigE was not required for survival in the presence of hydrogen peroxide or paraquat, two inducers of oxidative stress (data not shown). Either SigE is not involved in combating oxidative stress in B. bronchiseptica, or other oxidative-stress responsive pathways compensate for SigE when it is absent. Growth in the murine respiratory tract is not affected by the lack of sigE B. bronchiseptica RB50 colonizes the respiratory tract of immunocompetent mice, causing an asymptomatic infection that is eventually cleared by the immune system. To determine whether B. bronchiseptica SigE contributes to colonization and persistence in the respiratory tract, groups of C57BL/6 mice were inoculated with RB50 or RB50ΔsigE.