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The structure of a pyoverdine produced by a Pseudomonas tolaasii-like isolate
D U Fernández1, R Fuchs, K Taraz
1Institut für Organische Chemie der Universität zu Köln, Germany.
Abstract:
Cultures of Agaricus bisporus, the most extensively cultivated mushroom, can be infected severely by Pseudomonas tolaasii. This pathogen is characterized by the so-called white line reaction, a precipitate formed on agar plates between its colonies and those of P. reactans, both belonging to the collective species P. fluorescens. A recent study has shown that a group of P. tolaasii isolates can be subdivided into two groups or 'siderovars', based on the pyoverdines they produce (Munsch et al. 2000). One group of strains is characterized by the pyoverdine described by Demange et al. (1990). A representative of the second group (strain Ps3a) was found to produce the same pyoverdine as a strain which had been classified before as P. aureofaciens. However, based mainly on 16S rRNA gene sequence comparisons and REP-PCR generated fingerprints, the two strains are not identical. They are also distinguishable from the P. tolaasii type strain.
Insights
Pseudomonas tolaasii, a mushroom pathogen, can be classified into two siderovars based on pyoverdine production. These siderovars, identified through molecular methods, are distinct from each other and the P. tolaasii type strain.
Area of Science:
- Microbiology
- Plant Pathology
- Bacterial Genetics
Background:
- Agaricus bisporus cultivation is threatened by Pseudomonas tolaasii infections.
- Pseudomonas tolaasii exhibits a characteristic 'white line reaction' with P. reactans.
- Previous research identified two siderovars within P. tolaasii based on pyoverdine profiles.
Purpose of the Study:
- To investigate the taxonomic relationship between P. tolaasii siderovars and related Pseudomonas species.
- To differentiate between P. tolaasii strains and a strain previously classified as P. aureofaciens using molecular techniques.
Main Methods:
- Analysis of pyoverdine production by P. tolaasii isolates.
- 16S rRNA gene sequence comparisons.
- Repetitive element palindromic PCR (REP-PCR) fingerprinting.
Main Results:
- One P. tolaasii siderovar produces a known pyoverdine, while the second produces a pyoverdine similar to that of P. aureofaciens.
- 16S rRNA gene sequences and REP-PCR fingerprints distinguished the strains.
- The P. aureofaciens-like strain (Ps3a) was found to be distinct from the P. tolaasii type strain.
Conclusions:
- Pyoverdine profiles can aid in the subdivision of P. tolaasii.
- Molecular methods confirm distinctness between P. tolaasii siderovars and related species.
- The classification of the strain Ps3a requires further investigation beyond pyoverdine analysis.