Limimonas halophila gen. nov., sp. nov., an extremely halophilic bacterium in the family Rhodospirillaceae

Abstract

A novel, Gram-staining-negative, non-pigmented, rod-shaped, strictly aerobic, extremely halophilic bacterium, designated strain IA16(T), was isolated from the mud of the hypersaline Lake Aran-Bidgol, in Iran. Cells of strain IA16(T) were not motile. Growth occurred with 2.5-5.2 M NaCl (optimum 3.4 M), at pH 6.0-8.0 (optimum pH 7.0) and at 30-50 °C (optimum 40 °C). Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain IA16(T) belonged in the family Rhodospirillaceae and that its closest relatives were Rhodovibrio sodomensis DSM 9895(T) (91.6 % sequence similarity), Rhodovibrio salinarum NCIMB 2243(T) (91.2 %), Pelagibius litoralis CL-UU02(T) (88.9 %) and Fodinicurvata sediminis YIM D82(T) (88.7 %). The novel strain's major cellular fatty acids were C19 : 0 cyclo ω7c and C18 : 0 and its polar lipid profile comprised phosphatidylglycerol, diphosphatidylglycerol, four unidentified phospholipids, three unidentified aminolipids and two other unidentified lipids. The cells of strain IA16(T) contained the ubiquinone Q-10. The G+C content of the novel strain's genomic DNA was 67.0 mol%. The physiological, biochemical and phylogenetic differences between strain IA16(T) and other previously described taxa indicate that the strain represents a novel species in a new genus within the family Rhodospirillaceae, for which the name Limimonas halophila gen. nov., sp. nov. is proposed. The type strain of Limimonas halophila is IA16(T) ( = IBRC-M 10018(T) = DSM 25584(T)).