Production and Comparison of Peptide Siderophores from Strains of Distantly Related Pathovars of Pseudomonas syringae and Pseudomonas viridiflava LMG 2352

Abstract

The production of peptide siderophores and the variation in siderophore production among strains of Pseudomonas syringae and Pseudomonas viridiflava were investigated. An antibiose test was used to select a free amino acid-containing agar medium favorable for production of fluorescent siderophores by two P. syringae strains. A culture technique in which both liquid and solid asparagine-containing culture media were used proved to be reproducible and highly effective for inducing production of siderophores in a liquid medium by the fluorescent Pseudomonas strains investigated. Using asparagine as a carbon source appeared to favor siderophore production, and relatively high levels of siderophores were produced when certain amino acids were used as the sole carbon and energy sources. Purified chelated siderophores of strains of P. syringae pv. syringae, P. syringae pv. aptata, P. syringae pv. morsprunorum, P. syringae pv. tomato, and P. viridiflava had the same amino acid composition and spectral characteristics and were indiscriminately used by these strains. In addition, nonfluorescent strains of P. syringae pv. aptata and P. syringae pv. morsprunorum were able to use the siderophores in biological tests. Our results confirmed the proximity of P. syringae and P. viridiflava; siderotyping between pathovars of P. syringae was not possible. We found that the spectral characteristics of the chelated peptide siderophores were different from the spectral characteristics of typical pyoverdins. Our results are discussed in relation to the ecology of the organisms and the conditions encountered on plant surfaces.The species Pseudomonas syringae contains all of the phytopathogenic and oxidase-negative fluorescent pseudomonads except Pseudomonas viridiflava (27,38). P. syringae is divided into 57 pathovars that are pathogenic for numerous monocot and dicot crops (13). P. syringae strains are well adapted to conditions on plant surfaces. A better understanding of the ecological benefits of these pathogens is necessary if new and efficient methods of biological control are to be developed. One of these benefits could be the production of peptide siderophores in iron-deficient environments (8,33). In general, the peptide siderophores produced by fluorescent Pseudomonas strains are pyoverdins (2, 3). All pyoverdins contain the same quinoline chromophore, a peptide chain, and a dicarboxylic acid (or the corresponding amide) connected to the chromophore. The peptide chain is always the same for a given strain but is different in different strains and species (2). Two partially characterized peptide siderophores of P. syringae that have been described (8, 33) have Fe(III)-binding constants at pH 7.0 of about 1 ϫ 10 25 . These values are 10 times higher than the values obtained for pyoverdins produced by saprophytic fluorescent Pseudomonas strains (8, 33). Therefore, it would be interesting to know whether production of these molecules is common in P. syringae strains and whether the molecules are effectively produced on plant surf...

Investigation of Siderophore production and Antifungal activity against Phytophthora capsici as related to Iron (III) nutrition by Lysobacter antibioticus HS124

“…The siderophore activity (and production) in HS124 increased over a relatively wide range of iron concentrations reaching a peak at 100 µM Fe (III), followed by a sharp decline at concentrations beyond 100 µM. The observed pattern is generally consistent with earlier reports that gradual repression of siderophore production was observed with increasing concentrations (0 to 10 µM) of iron (III) in Pseudomonas syringae (Bultreys and gheysen, 2000), and that total repression of siderophore production by the same species was observed at iron (III) concentration of 100 µM (Laine et al, 1996). However, our findings suggest that Fe (III) requisition by HS124 was considerably higher than those of other siderophore producing bacteria.…”

“…Siderophores produced by Pseudomonas syringae and Pseudomonas viridiflava (Bultreys and Gheysen, 2000), for example, played a vital role in the biocontrol of plant pathogens. Similarly siderophores produced by Pseudomonas fluorescens promoted plant growth via competition for iron (Loper and Henkels, 1999).…”

The complete genome sequence of the Arabidopsis and tomato pathogen Pseudomonas syringae pv. tomato DC3000

“…Siderophores are low molecular weight, high-affinity iron(III) chelators that function as important virulence factors in many bacterial pathogens because of their role in sustaining growth in iron-limited host environments. Synthesis of the siderophore pyoverdin is well documented among fluorescent pseudomonads (41), and the required genes are present in a single cluster in DC3000. Also, a cluster of genes homologous to those required for biosynthesis of the siderophore pyochelin by P. aeruginosa has been found.…”

Characterization of Fluorescent and Nonfluorescent Peptide Siderophores Produced by Pseudomonas syringae Strains and Their Potential Use in Strain Identification

“…A better understanding of the ecological benefits of these pathogens is necessary if efficient methods of biological control are to be developed. Recently, it was shown that an apparently identical fluorescent peptide siderophore is produced by strains belonging to distantly related pathovars of P. syringae and to the closely related phytopathogenic species Pseudomonas viridiflava (7). The spectral characteristics of the molecule differ from those of typical pyoverdins (7), which are the fluorescent peptide siderophores generally produced by saprophytic and opportunistic animal pathogen fluorescent Pseudomonas species (2,4).…”

“…Recently, it was shown that an apparently identical fluorescent peptide siderophore is produced by strains belonging to distantly related pathovars of P. syringae and to the closely related phytopathogenic species Pseudomonas viridiflava (7). The spectral characteristics of the molecule differ from those of typical pyoverdins (7), which are the fluorescent peptide siderophores generally produced by saprophytic and opportunistic animal pathogen fluorescent Pseudomonas species (2,4). The production of the fluorescent siderophore by P. syringae is activated under conditions that are related to conditions encountered on plant surfaces (7,23,30,42,43).…”