Kandeliimicrobium roseum gen. nov., sp. nov., a new member of the family Rhodobacteraceae isolated from mangrove rhizosphere soil.

A Gram-stain-negative, non-flagellated, short rod-shaped bacterium, designated XY-R6, was isolated from the rhizosphere soil of a mangrove plant, Kandelia candel (L.) Druce, in Mai Po Nature Reserve, Hong Kong. Growth of strain XY-R6 was observed at pH 5.0-9.5 (optimum 6.5-8.0), between 8 and 42 °C (optimum 28-34 °C), and in the presence of 0-9.5 % (w/v) NaCl (optimum 1-4 %). The predominant isoprenoid quinone was ubiquinone-10. The major fatty acids were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c) (55.61 %), C19 : 0cycloω8c (21.59 %) and C16 : 0 (11.24 %). The major polar lipids were phosphatidylglycerol, phosphatidylethanolamine, aminolipid, phosphatidylcholine and diphosphatidylglycerol. The genomic DNA G+C content of strain XY-R6 was 69.3 mol%. Phylogenetic analyses, based on 16S rRNA gene sequences, revealed that strain XY-R6 belonged to the family Rhodobacteraceae of the class Alphaproteobacteria and formed a distinct lineage, showing the highest gene sequence similarities to the members of genus Wenxinia(94.5-94.3 %), followed by the genera Profundibacterium (94.3 %), Defluviimonas(93.8-92.5 %), Oceanicola (93.8 %) and Cereibacter (93.7 %). Similarities to other genera within the family Rhodobacteraceae were below 94.0 %. Based on comprehensive phenotypic, phylogenetic and chemotaxonomic characterization, it is indicated that strain XY-R6 represents a novel species of a new genus in the family Rhodobacteraceae, for which the name Kandeliimicrobium roseum gen. nov., sp. nov. is proposed, with XY-R6 (=MCCC 1K01498=KCTC 52266=DSM 104294) as the type strain.