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This study focuses on the microbial content and diversity of soil halophiles in the semi-arid areas of Jordan as adaptation of these organisms to desert harsh conditions could potentially lead thesm to produce novel secondary metabolites and thus to important discoveries. Soil samples were collected from three locations representing the semi-arid environments in Jordan and were studied for their total halophilic microbial content at wide range concentrations of NaCl (0.85% - 30%). Microbial count at all locations maximized at 0.85% with an average of 1909 CFU gm-1 soil and decreased as the NaCl concentration increased only in the Azraq-Eastern Jordan that showed extremely halophilic microbial content with an average of 29 CFU gm-1 soil and 2-5 diverse colony types at 30% NaCl. The growth response of all recovered microorganisms at different concentrations of NaCl (0.85%-30%) was observed after 14 days of incubation at 28 ˚C as weak (+1), moderate (+2), and good growth (+3). Accordingly, the recovered isolates were categorized into halotolerant (0.85%-30%), moderately halophilic (5%-15%), and extremely halophilic (15%-30%) groups. Macroscopic and microscopic examination of the extremely halophilic isolates revealed that they are either Gram positive bacilli or yeasts with the ability of extreme halophiles to produce orange to rose and cream pigments. Growth of the AQ332 and AQ334 isolates at extreme hyper-saline conditions indicates that they are highly specialized microorganisms and deserve to be studied further in future.
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