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

Two novel bacterial strains, SLG210-30A1(T) 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 SLG210-30A1(T) and SLG210-19A2 were 61.8 mol% and 61.6 mol% respectively. Strain SLG2110-30A1(T) had Q10 as the predominant respiratory ubiquinone, and C-16:0 (28.4%), C-17:0 (11.6 %), C-18:0 (22.1 %) and C-18:1 omega 7c (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 SLG210-30A1(T) and SLG210-19A2 showed the highest similarities with Glycocaulis abyssi MCS 33(T) (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 33(T) to strains SLG210-30A1(T) and SLG210-19A2 was 37.4 +/- 4.4 % and 36.1 +/- 1.1%, respectively. Based on different physiological, biochemical, and phylogenetic characteristics, strains SLG210-30A1(T) and SLG210-19A2 represent a novel species of the genus Glycocaulis. The name Glycocaulis albus is therefore proposed with strain SLG210-30A1(T) (=LMG 27741(T)=CGMCC 1.12766(T)) as the type strain. An emended description of the genus Glycocaulis is also provided.