Siderophores of halophilic archaea and their chemical characterization

Abstract

Nine halophilic archaea <i style="">viz</i>., <i style="">Halobacterium salinarum, Halobacterium</i> sp.1, <i style="">Halobacterium</i> sp.2, <i style="">Halobaculum</i> sp., <i style="">Halococcus saccharolyticus</i>, <i style="">Halorubrum saccharovorum</i>, <i style="">Haloterrigena turkmenica</i>, <i style="">Halogeometricum</i> sp. and <i style="">Natrialba</i> sp. isolated from marine salterns around Bhavnagar coast were screened for siderophore production. Five isolates viz., <i style="">Halococcus saccharolyticus</i>, <i style="">Halorubrum saccharovorum</i>,<i style=""> Haloterrigena turkmenica</i>, <i style="">Halogeometricum</i> sp. and <i style="">Natrialba</i> sp. produced siderophores as evidenced by positive reaction in FeCl₃ test, CAS assay and CAS agar plate test. Determination of chemical nature of siderophores by chemical assays and bioassays identified them as carboxylates. Quantification of siderophores indicated <i style="">Halorubrum saccharovorum</i> to be the maximum siderophore producer (2.62 RE mg/ml<b style="">)</b> and <i style="">Halococcus saccharolyticus</i> to be the least<b style=""> </b>(1.33 RE mg/ml). The present study is the first report on siderophore production in Indian haloarchaeal strains. Mechanism of iron assimilation in four non-siderophore isolates still needs to be investigated further.