Polyphasic characterization of a new extremely halophilic bacterium isolated from an Iranian hypersaline lake

Abstract

Halophilic bacteria are represented by heterogeneous physiological and taxonomic groups. Studies of such bacteria are of great importance, as they may produce compounds of industrial interest, such as extracellular hydrolytic enzymes that have diverse potential use in biotechnological processes. The aim of the study was the taxonomic characterization of an extremely halophilic bacterium isolated from Aran-Bidgol hypersaline lake in Iran. A polyphasic approach including phenotypic, chemotaxonomic and phylogenetic characterization was used for the identification of the new extremely halophilic bacterium. During the study of the microbial population in hypersaline lakes in Iran, an aerobic, Gram-staining-negative, non-pigmented, rod shaped, extremely halophilic bacterium, designated strain IA16T, was isolated and characterized. Phylogenetic analysis based on the comparison of 16S rRNA gene sequences revealed that strain IA16T is a member of the family Rhodospirillaceae; however its similarity was as low as 91.6 %, 88.9 % and 88.7 % to the most closely related taxa including Rhodovibrio, Pelagibius and Fodinicurvata type species, respectively. Growth occurred between 2.5 and 5.2 M NaCl and optimally at 3.4 M NaCl. The optimum pH and temperature for growth of strain IA16T were pH 7.0 and 40 °C, respectively. The major cellular fatty acids of the isolate were C19:0 cyclo ω7c and C18:0. The polar lipid pattern of strain IA16T consisted of diphosphatidylglycerol, phosphatidylglycerol, two phospholipids and two glycolipids. The G+C content of the genomic DNA of this strain was 67.0 mol%. On the basis of polyphasic evidence from this study, IA16T is suggested as representative of a new species in a new genus within the family<br><br>Rhodospirillaceae, for which the name Limimonas halophila gen. nov., sp. nov. is proposed.