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International Journal of Soil Science

Year: 2008  |  Volume: 3  |  Issue: 1  |  Page No.: 28 - 34

Production of Hydroxamate-Type of Siderophores by Rhizobium strains from Sesbania sesban (L.) Merr.

M. Sridevi and K.V. Mallaiah


Twenty six Rhizobium strains isolated from root nodules of Sesbania sesban (L.) Merr. were screened for their ability to produce siderophores. Among the twenty six strains, twenty strains produced hydroxamate-type of siderophores in Fiss-glucose mineral medium. The maximum amount of siderophore was produced by Rhizobium strain 22. The production of siderophore started at 8 h and reached maximum after 24 h. The addition of limited amount of iron in the media increased growth as well as siderophore production. Fiss-glucose mineral medium supplemented with 1% sucrose and 0.1% (NH4)2SO4 increased siderophore production. UV-spectrophotometric scanning of purified siderophore showed absorption maxima in the range of 500-520 nm and indicating that it belongs to dihydroxamate-type of siderophore. Tryptophan and tyrosine were identified as conjugated amino acids of the purified siderophore. The outer membrane protein profiles of the Rhizobium strain 22 grown in high iron containing medium revealed an unique protein band of molecular mass 45 kDa.

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