Glycocaulis albus sp. nov., a moderately halophilic dimorphic prosthecate bacterium isolated from petroleum-contaminated saline soil

Two novel bacterial strains, SLG210-30A1T and SLG210-19A2, which shared 99.9 % 16S rRNA gene sequence similarity with each other, were isolated from petroleum-contaminated saline soil in Shengli Oilfield, eastern China. Cells were Gram-stain-negative, motile, aerobic, mesophilic and moderately halophilic. They could grow chemoheterotrophically with oxygen as an electron acceptor. Morphologically, cells were typical Caulobacteria-type dimorphic prosthecate bacteria. The genomic DNA G+C contents of strains SLG210-30A1T and SLG210-19A2 were 61.8 mol% and 61.6 mol% respectively. Strain SLG210-30A1T had Q10 as the predominant respiratory ubiquinone, and C16 : 0 (28.4 %), C17 : 0 (11.6 %), C18 : 0 (22.1 %) and C18 : 1ω7c (14.0 %) as the major cellular fatty acids. The polar lipids of the two isolates were some glycolipids, a lipid, a phospholipid, an aminoglycolipid and an aminophospholipid (all unidentified). The 16S rRNA gene sequences of strains SLG210-30A1T and SLG210-19A2 showed the highest similarities with Glycocaulis abyssi MCS 33T (99.8–99.9 %), but low sequence similarities (<94.7 %) with type strains of other members of the family Hyphomonadaceae . However, the DNA–DNA relatedness of G. abyssi MCS 33T to strains SLG210-30A1T and SLG210-19A2 was 37.4±4.4 % and 36.1±1.1 %, respectively. Based on different physiological, biochemical, and phylogenetic characteristics, strains SLG210-30A1T and SLG210-19A2 represent a novel species of the genus Glycocaulis . The name Glycocaulis albus is therefore proposed with strain SLG210-30A1T ( = LMG 27741T = CGMCC 1.12766T) as the type strain. An emended description of the genus Glycocaulis is also provided.