Conclusion In this study we show that siderophore-mediated iron uptake is important for the virulence of P. luminescens to insect larvae. This is similar to what has been reported for other pathogens and further highlights the relevance of Photorhabdus as a model for studying bacteria-host interactions [43]. Moreover, in contrast to what we previously reported in another species of Photorhabdus (P. temperata K122) [11], we show that siderophore-mediated

selleck chemical iron uptake in P. luminescens TT01 is not required for the growth and development of the nematode. Therefore it appears that different Photorhabdus-Heterorhabditis complexes have specific requirements for iron. In addition we show that the yfeABCD operon (encoding the Yfe divalent cation transporter)

is required for virulence in some, but not all, insect hosts. Although the Yfe transporter can mediate the uptake of either Fe2+ or Mn2+ we have shown that this transporter is involved in iron uptake during pathogenicity. On the other hand we present data that suggests that the Yfe transporter may be involved in Mn2+-uptake during growth in the gut lumen of the IJ nematode. Therefore, the substrate specificity of the Yfe www.selleckchem.com/CDK.html transporter in P. luminescens TT01 appears to be dependent on the invertebrate host colonized by the bacteria. Methods Bacterial strains and growth conditions Strains used in this study are listed in Table 3. Photorhabdus temperata K122,

Photorhabdus luminescens subsp laumondii TT01 and Escherichia coli strains were routinely cultured in Luria-Bertani (LB) broth or on LB agar and were incubated at 30°C or 37°C respectively. CAS agar, for the detection of siderophores, was prepared by adding CAS solution (1:10 (v:v)) into the LB agar just before pouring. CAS solution was prepared as described previously [11]. When required antibiotics were added at the following final concentrations: kanamycin (Km) 50 μg/ml, ampicilin (Amp) 100 μg/ml, chloramphenicol (Cm) 20 μg/ml and rifampicin Anidulafungin (LY303366) (Rif) 100 μg/ml. Table 3 Bacterial strains used in this study Strain Genotype Reference Photorhabdus     P. temperata (Pt) K122 Spontaneous RifRmutant Joyce and www.selleckchem.com/products/R406.html Clarke, 2003 P. luminescens (Pl) TT01 Spontaneous RifRmutant Bennett and Clarke, 2005 BMM417 K122 exbD::Km Watson and Clarke, 2005 BMM430 TT01 ΔexbD This study BMM431 (Δyfe) TT01 ΔyfeABCD This study BMM432 (Δfeo) TT01 ΔfeoABC This study BMM433 TT01 ΔexbD Δyfe This study BMM434 TT01 ΔexbD Δfeo This study BMM435 TT01 Δfeo Δyfe This study BMM436 TT01 ΔexbD Δfeo Δyfe This study E.coli     S17-1(λpir) lysogenised with λpir, replication of ori R6K Laboratory stock Construction of deletions in exbD, feoABC and yfeABCD Targeted deletion mutants were constructed as previously described [10].