This is a refereed journal and all articles are professionally screened and reviewed O RIGINAL A RTICLE Advances in Environmental Biology, 2(2): 63-69, 2008 ISSN 1995-0756 © 2008, American-Eurasian Network for Scientific Information 63 Corresponding Author: Mohammed Wedyan, Department of Biology, Al Hussein Bin Talal University, Ma'an, Jordan. E-mail: mwedyan@ahu.edu.jo Isolation and Characterization of Halophilic Bacteria from the Dead Sea Coast, Jordan Khaled A. Tarawneh, Mohammed Wedyan, Mahmoud A. Al-zou'bi, Khaled M. Khleifat and 1 2 1 1 Amjed Tarawneh 1 Department of Biological Sciences, Mutah University, Mutah, Jordan. 1 Department of Biology, Al Hussein Bin Talal University, Ma’an, Jordan. 2 Khaled A. Tarawneh, Mohammed Wedyan, Mahmoud A. Al-zou'bi, Khaled M. Khleifat and Amjed Tarawneh: Isolation and Characterization of Halophilic Bacteria from the Dead Sea Coast, Jordan: Adv. Environ. Biol., 2(2): 63-69, 2008 ABSTRACT: Seven halophilic bacterial strains were isolated from sediment sample obtained from Dead Sea coast, Al Karak, Jordan. The strains showed good growth in medium containing 10-15% (w/v) NaCl at 37°C. The Morphological, biochemical and physiological analysis were done to characterize the seven Isolates. All of the isolates were Gram negative and required different NaCl concentration for growth. The optimum conditions such as temperature, pH and salts (NaCl) were determined. The utilization of organic compounds; Fructose, Lactose, Glucose, Sucrose and the hydrolysis of organic compounds such as; casein, gelatin, aesculin, starch, tween20 and tween 80 were also ivestigated. The effect of NaCl concentration divided the isolates into three groups; The first group contained two isolates H4 and H5 which were assigned extreme halophilic bacteria . They were similar to the genus Haloferax, especially H. volcani which was isolated from the Dead Sea, with little differences in some characterization. The second group contained four isolates similar in morphological, physiological and biochemical characterization, H1, H3, H6 and H7, were assigned moderately halophilic bacteria. These isolates were different from those and known species isolated from the Dead Sea. The third group contained one isolate moderately halophilic H2 which was different from the second group isolates and from some other known species isolated from the Dead Sea. Key words: Hypersaline, Halophilic bacteria, Salteners, Dead Sea Introduction In spite of its high salinity, the Dead Sea is the natural habitat for a variety of microorganisms[1, 2,3]. These include unicellular green algae of the genus Dunaliella, which is the sole primary producers in the lake, and a variety of heterotrophic prokaryotes, aerobes, anaerobes as well as Archaea[4,5]. A number of Dead Sea microorganisms have been isolated and were maintained in culture such as Archaea, Haloarcula marismortui[3]. A similar strain was isolated from the Dead Sea in the late 1960s[6]. This organism has become a popular model for the study of halophilic enzymes, and its genome was recently sequenced[7]. Haloferax volcanii isolated in the early 1970s from surface sediments[8]. Halorubrum sodomense isolated from the archaeal bloom that developed in the Dead Sea in 1980[9]. Halobaculum gomorrense, isolated during the bloom of 1992[10]. Additional archaeal isolates have been obtained in the