Microaerobic, anaerobic, and ambient oxygen incubation conditions are abbreviated as “Micro”, “Ana” and “O2” respectively. Statistically significant (P < 0.05) differences are highlighted with * and indicate comparisons with the wildtype. The experiment was repeated three times independently and samples were

tested in at least three replicates per experiment. Data are presented as mean ± standard error. The observed impact of RPs on biofilm formation is likely mediated by multiple factors, including the metabolic and energy requirements that facilitate efficient growth and persistence in response to the THZ1 properties of a given niche. However, our results highlight the overall Selleckchem MGCD0103 importance of RPs in Smad inhibitor C. jejuni’s adaptations to different niches as well as their differential contribution to promote the pathogens survival and cognate persistence via biofilm formation in disparate environments. Since RPs contribute to C. jejuni survival phenotypes in a manner that was dependent on the incubation temperature and/or oxygen concentration, it was important

to investigate if the deletion of RPs will impact C. jejuni’s interactions with the cells of hosts that possess markedly different physiology and body temperatures. For this purpose, the interactions of the mutants with human intestinal cells (INT-407) and primary chicken intestinal epithelial cells (PIC) were analyzed using the gentamicin Branched chain aminotransferase protection assay as described elsewhere [29, 30]. All cells were incubated in a tissue culture chamber (5% CO2) either at 37°C or 42°C corresponding to the hosts’ body temperatures. Our results show that ΔnrfA adhered to PIC in significantly higher numbers, while ΔfdhA and ΔhydB were significantly deficient in adherence as well as invasion of the chicken cell monolayers (Figure 3a). While assessing intracellular survival for the mutants in PIC, no CFUs were retrieved for any of the strains, including the wildtype.

This observation corroborated a previous study, which showed that during overnight incubation C. jejuni can escape the PIC monolayers due to the bacterium’s inherent mode of colonization of chicken intestinal epithelia [31]. Specifically, Van Deun et al. [31] showed that C. jejuni strains that invaded PIC were not able to proliferate in the intracellular milieu and rapidly exited the cells, supposedly to replicate in the intestinal mucus. It was also suggested that this mode of infection (i.e. short-term entry to the PIC) allows C. jejuni to escape mucosal clearance [31]. In comparison to the interaction with PIC, all mutants were defective to a varying degree, albeit if not always significantly, in adherence to INT-407 cells, while ΔmfrA, ΔfdhA and ΔhydB were also impaired in their invasion potential and ΔnrfA showed an increased ability for intracellular survival (Figure 3b, Table 1).