Isolation of siderophore producing halophilic bacteria from the agricultural soil in Karaj Eshtehard

Iron is the fourth most abundant element of the earth’s crust. While iron is widespread in the environment, it is often considered biologically unavailable as it is often only found in the form of highly insoluble Fe (III) oxides؛ So most microbes inhabiting aerobic, neutral or alkaline environments live in a state of permanent iron deficiency. A commonstrategie for iron sequestration is through the excretion of chelators, with high affinity for Fe (III), known as siderophores.Some biotechnological application of siderophores include: plant growth promoting that occurs via the removal ofpathogens, antimicrobial activity, removing toxic methals off the soils, medical and therapeutic purposes. For isolation of halophilic bacteria from the soil and determination of the siderohore producing ability a total of 90 microorganisms were isolated from nine soil samples based on 12%MH medium, of which seven were determine as moderate halophiles. For inducing of siderophore production, solution of undefined parts of medium such as peptone and yeast extract deferatedseparately by extraction with same volume of 3% 8-hydroxyquinoline in chloroform. Since all the isolates were Grampositivebacteria and CAS universal assay, is unsuitable to cultivate some microorganisms such as Gram-positive bacteria,using an overlay technique (O-CAS) in which a modified chrome azurol S medium is cast upon culture agar plates, two moderate halophile siderophore producing bacteria were identified. The sign of siderophore prodution is color changing and formation of orange halo on blue background CAS media. Functional group identified through chemical assays including Arnow, Csaky and spectrophotometric tests and belongs to hydroxamate-type of siderophores.

کلیدواژه ها:

Siderophore ، chelators ، Halophile ، O-CAS