jejuni strains with deletion in five individual genes encoding essential RPs subunits were used. The mutations targeted the nitrate reductase (ΔnapA; Cj0780), nitrite reductase (ΔnrfA; Cj1357c), formate #PD0332991 in vivo randurls[1|1|,|CHEM1|]# dehydrogenase (ΔfdhA; Cj1511c), hydrogenase (ΔhydB; Cj1266c), methylmenaquinol:fumarate reductase (ΔmfrA; Cj0437; this gene was previously identified as encoding a succinate dehydrogenase subunit, sdhA). It was previously shown that the deletion of these genes resulted in the loss of the catalytic functions of the associated respiratory enzymes; however,
the mutants retained a generation time that was similar to that of the parental strain [8–10]. Although the mutants’ role in respiration has been previously investigated, neither the impact of the cognate RPs on survival phenotypes such as H2O2 resistance and biofilm formation nor their potential contribution to adaptation under varying temperature and oxygen conditions were analyzed. Further, the potential interactions of these LDN-193189 price mutants with human and chicken intestinal cells were not characterized. Here, we show that individual RPs can contribute to C. jejuni’s motility,
oxidative stress response (H2O2 resistance), biofilm formation, and in vitro interactions with host cells. Our data highlight a role for RPs in C. jejuni’s adaptation to different environmental conditions as well as its in vitro interactions with intestinal cells of disparate hosts. Results and discussion C. jejuni’s motility is considered important for effective colonization of hosts as well as chemotaxis  and, subsequently, persistence in different niches. Therefore, we investigated whether the deletion of the RPs might differentially impact C. jejuni’s motility in response to different temperatures. Examination under scanning electron microscopy showed that none of the mutants were defective in flagellation, regardless of the incubation temperature (data not shown). Further, the mutants’ motility was evaluated using 0.4% semisolid agar as described elsewhere [15, 17]. Using this method, motility under anaerobic conditions could not be accurately assessed, because the zones of motility
were not defined and sufficiently large for reliable measurement. This precluded the assessment of the 4��8C effect of oxygen concentration on motility. However, our results show that during incubation under microaerobic conditions, ΔfdhA displayed significantly decreased zone of motility as compared to the wildtype, while the deletion of hydB did not impact this phenotype (Figure 1a, Table 1). Alternatively, ΔnapA, ΔnrfA, and ΔmfrA exhibited significantly increased motility as compared to the wildtype (Figure 1a, Table 1). Since the oxidation of formate is considered a major energy source for C. jejuni, the motility defects that are displayed by the ΔfdhA as compared to the other mutants and the wildtype strain can be perhaps attributed to the role of the formate dehydrogenase in energy metabolism.