Abstract
Fluorescent Pseudomonas (FP) is a major group of plant growth promoting rhizobacteria
and a well-known synthesizer of siderophores, which imparts a selective advantage on
rhizosphere competence and their biocontrol traits. The present study was aimed at examining
the factors affecting the production of siderophores and their potential biocontrol
traits. Sixteen FP isolates were shortlisted based on their siderophore-producing ability in
chrome azural S medium. The isolates were checked for variations in siderophore production
under varying incubation times, temperatures, pH, iron (Fe3+) concentrations and
mutagens. In addition, the iron binding affinity of siderophores, mycelial inhibition assay
and plant growth promotion traits were assessed. Results showed that the siderophore
production was highly influenced by the time of incubation, changes in pH, temperature
and iron concentration. Chemical characterization showed that the produced siderophores
were hydroxamates. Maximum siderophore production was observed at pH 7 whereas UV
and EtBr exposure invariably suppressed siderophore production drastically in all isolates.
All FPs from maize rhizosphere showed excellent siderophore production which could be
due to the competence in strategy-II of the plant rhizosphere and significant growth inhibition
on Fusarium oxysporum. Our results suggest the inclination of siderophores to iron, in
terms of various criteria affecting production and the possible role of environmental mutations
that affect the natural iron harvesting mechanism.
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Authors and Affiliations
Jayamohan Nellickal Subramanyan