Ornithinibacillus halophilus sp. nov., a moderately halophilic, Gram-stain-positive, endospore-forming bacterium from a hypersaline lake

Abstract

A novel Gram-stain-positive, moderately halophilic bacterium, designated strain G8BT, was isolated from water of the hypersaline lake Aran-Bidgol in Iran and characterized taxonomically using a polyphasic approach. Cells of strain G8BT were rod-shaped, motile and produced oval endospores at a terminal position in swollen sporangia. Strain G8BT was strictly aerobic, catalase-positive and oxidase-negative. The strain was able to grow at NaCl concentrations of 0.5–12.5 % (w/v), with optimum growth occurring at 5–7.5 % (w/v) NaCl. The optimum temperature and pH for growth were 35–40 °C and pH 7.5–8.0, respectively. On the basis of 16S rRNA gene sequence analysis, strain G8BT was shown to belong to the genus Ornithinibacillus within the phylum Firmicutes and showed closest phylogenetic similarity with Ornithinibacillus bavariensis WSBC 24001T (97.6 %). The DNA G+C content of strain G8BT was 36.9 mol%. The major cellular fatty acids of strain G8BT were anteiso-C15 : 0, anteiso-C17 : 0, iso-C15 : 0 and iso-C16 : 0, and its polar lipid pattern consisted of phosphatidylglycerol, diphosphatidylglycerol, four unknown phospholipids and an unknown aminolipid. The isoprenoid quinones were MK-7 (98 %) and MK-8 (2 %). Strain G8BT contained a peptidoglycan of type A4β, l-Orn–d-Asp. All these features confirmed the placement of isolate G8BT within the genus Ornithinibacillus . DNA–DNA hybridization experiments revealed a low level of relatedness (6 %) between strain G8BT and Ornithinibacillus bavariensis DSM 15681T. On the basis of evidence from this study, a novel species of the genus Ornithinibacillus , Ornithinibacillus halophilus sp. nov., is proposed, with strain G8BT ( = IBRC-M 10683T = KCTC 13822T) as the type strain.