Acquisition of iron by the non-siderophore-producing Pseudomonas fragi

Abstract

The iron requirement, siderophore production and iron uptake mechanisms of the type strain Pseudomonas fragi ATCC 4973 and five P. fragi isolates from meat were analysed. The strains exhibited a high sensitivity to iron starvation: their growth was strongly inhibited in medium supplemented with the iron chelator ethylenediamine di(hydroxypheny1acetic acid) or in medium treated with 8-hydroxyquinoline to remove contaminating iron. No siderophores were detectable in the growth supernatants of iron-starved cells. Cross-feeding experiments in iron-depleted medium showed, however, that the bacterial growth could be strongly stimulated by siderophores of foreign origin including desferriferrioxamine B, enterobactin and some pyoverdines. Moreover, all the strains were capable of efficiently using the iron sources present in their natural environment, i.e. transferrin, lactoferrin and haemoglobin. Iron starvation led to the specific production of supplementary outer-membrane proteins of apparent molecular mass ranging from 80 to 88 kDa. Furthermore, growth in the presence of exogenous siderophores resulted, in some strains, in the induction of siderophore-mediated iron uptake systems. For one strain the concomitant synthesis of an iron-regulated, siderophore-inducible outer-membrane protein was observed.

Effect of Exogenous Siderophores on Iron Uptake Activity of Marine Bacteria under Iron-Limited Conditions

“…This suggests that active factors in these extracts are siderophores which have stimulatory functions on the growth of V0210. Although growth stimulation of some terrestrial bacteria has been reported by the addition of exogenous siderophores (6,8,21), it is not clear whether those bacteria might have been stimulated to synthesize their own siderophores. Paper electrophoresis of siderophore extracts from V0210 cultures showed that the CAS-positive component was produced only after cultivation with each of the exogenous siderophores from the four Sid ϩ strains, V0122, V0304, V0902, and V1110.…”

“…All procedures were performed according to the method of Champomier-Verges et al (6). After cultivating bacteria in iron-replete or iron-deficient media for 48 h, cells from 5-ml cultures were harvested by centrifugation and then resuspended in microcentrifuge tubes in 1 ml of 50 mM Tris-HCl-0.5 mM MgCl 2 buffer, pH 7.4.…”

Characterization of the ferrioxamine uptake system of Nitrosomonas europaea

“…In some cases, siderophores produced by one micro-organism can be taken up by another. For instance, Arthrobacter flavescens is able to take up siderophores made by soil fungi and bacteria (Winkelmann, 1991), and the non-siderophore-producing Pseudomonas fragi uses exogenous siderophores, such as ferrioxamine, enterobactin and some pyoverdines, for its Fe nutrition (Champomier-Verges et al, 1996). Exogenous siderophores, such as cepabactin and coprogen, promote Fe uptake by Pseudomonas aeruginosa PAO1, while others, such as ferrichrome A, have no effect on its Fe nutrition, indicating the requirement for specific siderophore transporters (Meyer, 1992).…”

Elucidation of the Vibrio anguillarum Genetic Response to the Potential Fish Probiont Pseudomonas fluorescens AH2, Using RNA-Arbitrarily Primed PCR

“…Hence, presumably not just simple iron deficiency induces the vibE homologue, but a combination of a lack of iron and the presence of other components of the AH2 supernatant is required to induce the vibE homologue. From other studies (8,16) siderophores are known to positively affect the growth of bacteria other than the siderophore-producing organism. The examples include specific cross feeding (16) or stimulation of a non-siderophore-producing bacterium by addition of siderophore-containing supernatants from another producing organism (8).…”

“…From other studies (8,16) siderophores are known to positively affect the growth of bacteria other than the siderophore-producing organism. The examples include specific cross feeding (16) or stimulation of a non-siderophore-producing bacterium by addition of siderophore-containing supernatants from another producing organism (8). Although growth of V. anguillarum is inhibited after exposure to the siderophore-containing AH2 supernatant, the presence of siderophores of strain AH2 origin might positively affect the V. anguillarum siderophore synthesis apparatus, leading to production of novel V. anguillarum siderophores (e.g., anguibactin) and hence induction of the vibE homologue.…”