Pseudomonas siderophores: production, spectrophotometry detection and Botrytis suppression

Abstract

Siderophores are iron-chelating agents produced by almost all microorganisms in response to iron deficiency. Due to the requirement of iron for cell growth and metabolism, siderophore-mediated acquisition of iron plays a central role in determining the ability of different microorganisms to colonize plant roots and contributes to microbial interactions in the plant rhizosphere. In this study, five new Pseudomonas (Q14B, Q13B, Q7B, Q6B, Q1B), isolated from the rhizosphere of tomato in Morocco, were examined for siderophores production capacity. The results show that all five isolates produced siderophores on both solid and liquid mediums. In liquid medium, the highest level of production is obtained by Q13B (53.8%). Concerning siderophores’ chemical types, the five strains of Pseudomonas produce two types of siderophores hydroxamate and catecholate. It was shown by the peaks of absorbance in the wavelength 495 and between 420-450 nm for catecholate and hydroxamate-type siderophores respectively. The results showed that the production of siderophores is progressively inhibited with increasing concentrations of iron in the medium. The maximum production was obtained with a concentration of 0.5 μM, while the lowest was recorded at 10.0 μM of iron. The results of this study showed that the five Pseudomonas isolates producing siderophores could be potential biological control agents.