Halovulum dunhuangense gen. nov., sp. nov., isolated from a saline terrestrial spring

Abstract

A bacterial strain, YYQ-30T, isolated from a mixed water–sand–sediment sample collected from a terrestrial spring located in Dunhuang, China, was characterized with respect to its morphology, physiology and taxonomy. Cells of the strain were Gram-stain-negative, aerobic, oxidase- and catalase-positive, non-flagellated, oval to rod-shaped (0.5–1.0 μm wide and 1.1–6.6 μm long) and divided by binary fission. Growth was observed in the presence of 0–10.0 % (w/v) NaCl with optimal growth at 0–3.0 %, at pH 6.0–9.0 (optimum pH 7.0–8.5) and at 10–45 °C (optimum 30–37 °C). The isolate could reduce nitrate to nitrite and hydrolyse aesculin and gelatin (weakly), but was unable to degrade Tween 80 or starch. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YYQ-30T belongs to the family Rhodobacteraceae and forms a distinct lineage with the type strain of Albimonas donghaensis and forms a branch within a cluster constituted by the type strains of species of the genera Albimonas, Rhodovulum, Albidovulum, Haematobacter and Tropicimonas; levels of 16S rRNA gene sequence similarity between strain YYQ-30T and members of related genera ranged from 94.1 to 89.7  %. Strain YYQ-30T contained Q-10 as the predominant ubiquinone and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 70.0  %), C18 : 0 (9.5  %), summed feature 2 (one or more of C14  :  0 3-OH, iso-C16  :  1 I and C12  :  0 aldehyde; 6.9  %) and 11-methyl C18  :  1ω7c (6.0  %) as the principal fatty acids. The polar lipids comprised diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, three unidentified phospholipids, two unidentified aminolipids and five unknown lipids. The pufLM gene was detected. The G+C content of the genomic DNA was 71.7 mol%. Based on the phylogenetic, chemotaxonomic and phenotypic data obtained in this study, strain YYQ-30T is considered to represent a novel species in a new genus within the family Rhodobacteraceae, for which the name Halovulum dunhuangense gen. nov., sp. nov. is proposed. The type strain of Halovulum dunhuangense is YYQ-30T ( = LMG 27418T = MCCC 1A06483T).