IntroductionThis study aimed to identify and characterize novel siderophore-producing organisms capable of secreting high quantities of the iron-binding compounds. In the course of this, two not yet reported halophilic strains designated ATCHATand ATCH28Twere isolated from hypersaline, alkaline surface waters of Salar de Llamará and Laguna Lejía, respectively. The alkaline environment limits iron bioavailability, suggesting that native organisms produce abundant siderophores to sequester iron.MethodsBoth strains were characterized by polyphasic approach. Comparative analysis of the 16S rRNA gene sequences revealed their affiliation with the genusHalomonas. ATCHATshowed close similarity toHalomonas salicampiandHalomonas vilamensis, while ATCH28Twas related closest toHalomonas ventosaeandHalomonas salina. The ability of both strains to secrete siderophores was initially assessed using the chromeazurol S (CAS) liquid assay and subsequently further investigated through genomic analysis and NMR. Furthermore, the effect of various media components on the siderophore secretion by strain ATCH28Twas explored.ResultsThe CAS assay confirmed the ability of both strains to produce iron-binding compounds. Genomic analysis of strain ATCHATrevealed the presence of a not yet reported NRPS-dependant gene cluster responsible for the secretion of siderophore. However, as only small amounts of siderophore were secreted, further investigations did not lie within the scope of this study. Via NMR and genomic analysis, strain ATCH28Thas been determined to produce desferrioxamine E (DFOE). Although this siderophore is common in various terrestrial microorganisms, it has not yet been reported to occur withinHalomonas, making strain ATCH28Tthe first member of the genus to produce a non-amphiphilic siderophore. By means of media optimization, the produced quantity of DFOE could be increased to more than 1000 µM.DiscussionPhenotypic and genotypic characteristics clearly differentiated both strains from other members of the genusHalomonas. Average nucleotide identity (ANI) values and DNA–DNA relatedness indicated that the strains represented two novel species. Therefore, both species should be added as new representatives of the genusHalomonas, for which the designationsHalomonas llamarensissp. nov. (type strain ATCHAT= DSM 114476 = LMG 32709) andHalomonas geminasp. nov. (type strain ATCH28T= DSM 114418 = LMG 32708) are proposed.