, 2009). We first noticed that the yicJI mutant formed smaller colonies than the wild type and the Δfrz strains on LB-agar plates. We then compared the growth of the wild-type strain, the Δfrz mutant, and the ΔJI mutant during MDV3100 order agitated and static cultures in LB-medium. Whereas the growth curves of the wild-type and of the Δfrz mutants were similar under both conditions,

the ΔJI mutant was affected in its ability of adaptation to the stationary phase of growth (OD600 nm of the ΔIJ mutant culture is 1 or 0.7 U lower than that of the wild-type strain after 72 h of agitated or static growth, respectively; Fig. 4). We reported previously that the frz operon is involved in the survival mechanism of BEN2908 during the late stationary growth phase in LB medium and in serum. Indeed, during co-cultures under oxygen-restricted conditions (static cultures), the wild-type strain BEN2908 outcompeted Anti-infection Compound Library purchase the BEN2908Δfrz strain during the late stationary growth phase, but not during the

exponential growth phase. This phenotype is strongly affected by oxygenation, as it is not revealed when the co-cultures are agitated (Rouquet et al., 2009). We thus tested the survival ability of the ΔJI mutant under these co-culture conditions, and we found that its fitness is strongly affected during the late stationary phase of growth, even when the co-cultures are highly agitated (Fig. 5, A–C). As the effect of the Frz system on the survival ability of the bacteria during the late stationary phase of growth was found to depend on the composition

of the culture medium, we analyzed the survival ability of the ΔJI mutant during static co-cultures with the wild-type strains in minimal media in which the fitness of the Δfrz mutant is not or only slightly affected (d-glucose, d-fructose, d-sorbose, and d-psicose). In contrast to the Δfrz mutant, the survival ability of the ΔJI mutant is strongly affected during the late stationary phase of growth in all these minimal media (Fig. 5, D–G). As isoprimeverose was found to be a substrate of YicI, we also tested the survival ability of the ΔJI and the Δfrz mutants during static co-cultures Ergoloid with the wild-type strain in a minimal medium containing this sugar as a sole carbon source. Again, the fitness of the ΔJI mutant was strongly affected during the late stationary phase of growth (6.2 ± 1.0% of mutant in the population after 7 days of co-culture), whereas that of the Δfrz mutant was not (53.7 ± 1.6% of mutant in the population after 7 days of co-culture). In conclusion, although the phenotypes of the Δfrz and the ΔJI mutants are not completely similar, both frz and yicJI metabolic operons are involved in the fitness of the bacteria and are cotranscribed through molecular mechanisms that could involve the FrzR activator and phosphoryl group transfer.