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Article Dans Une Revue Science of the Total Environment Année : 2020

Flocking asbestos waste, an iron and magnesium source for Pseudomonas

Résumé

Iron and magnesium are essential nutrients for most microorganisms. In the environment, the availability of iron is low relative to that of magnesium. Microorganisms have developed various iron acquisition systems, which have been well studied, whereas few studies have examined magnesium acquisition. The production of siderophores is one of the efficient strategies widely used to sustain iron nutritional requirements. Many studies have shown that minerals, such as clays, iron oxides, and silicates, can serve as nutrient sources for bacteria. Asbestos, a natural fibrous silicate present in soil contains iron and/or magnesium, depending on the species of asbestos. Our aim was to study the acquisition of iron and magnesium from flocking asbestos waste by Pseudomonas aeruginosa and the involvement of the siderophores, pyoverdine and pyochelin. Flocking asbestos waste promoted growth under iron- and magnesium-limited conditions, together with a decrease in pyoverdine production, correlating with the dissolution of iron from the waste. In long-term experiments, flocking asbestos waste provided these two essential elements for bacterial growth and resulted in a decrease of iron in asbestos fibers. Among the enzymes required for pyochelin and pyoverdine synthesis, PchA and PvdJ were tagged with the fluorescent protein mCherry to analyze the expression patterns of proteins involved in siderophore production. Both enzymes were produced in the presence of flocking asbestos waste, suggesting a role of the pyoverdine and pyochelin pathway in asbestos dissolution. We investigated the involvement of each siderophore in iron and magnesium removal using mutants in one or both siderophore pathways. We observed a significant increase in iron extraction in the presence of siderophores and the absence of one of the two siderophores could be compensated by the other. Flocking asbestos waste represents an iron and magnesium source for P. aeruginosa, with iron removal linked to a siderophore-driven mechanism.
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hal-02981380 , version 1 (07-03-2022)

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Paternité - Pas d'utilisation commerciale

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Sébastien R. David, Sarah Fritsch, Anne Forster, Dris Ihiawakrim, Valérie Geoffroy. Flocking asbestos waste, an iron and magnesium source for Pseudomonas. Science of the Total Environment, 2020, 709, pp.135936. ⟨10.1016/j.scitotenv.2019.135936⟩. ⟨hal-02981380⟩
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