Phenylobacterium aquaticum sp nov., isolated from the reservoir of a water purifier

A Gram-reaction-negative, strictly aerobic, non-motile, non-spore-forming, rod-shaped bacterial strain designated W2-3-4(T) was isolated from the reservoir of a water purifier. This bacterium was characterized to determine its taxonomic position by using a polyphasic approach. Strain W2-3-4(T) grew well at 25-30 degrees C on nutrient and R2A agars. On the basis of 16S rRNA gene sequence similarity, strain W2-3-4(T) was shown to belong to the family Caulobacteraceaeand to be related to Phenylobacterium conjunctum FWC21(T) (98.0% sequence similarity) and Phenylobacterium haematophilum CCUG 26751(T) (97.2%). Lower sequence similarities were found with the type strains of all other recognized members of the genus Phenylobacterium (95.7-97.1%). The G+C content of the genomic DNA was 68.7mol%. The major respiratory quinone was Q-10 and the major fatty acids were summed feature 8 (comprising C-18 : (1)omega 7c and/or C-18 (:) (1)omega 6c), C-16 (:) (0), C-18 : 1 omega 7c 11-methyl and summed feature 3 (comprising C-16 : (1)omega 7c and/or C-16 (:) (1) omega 6c). The polar lipids were phosphatidylglycerol, an unknown phospholipid, four unknown glycolipids and three unidentified polar lipids. DNA-DNA relatedness values between strain W2-3-4(T) and its closest phylogenetically neighbours were below 7%. Strain W2-3-4(T) could be differentiated genotypically and phenotypically from recognized species of the genus Phenylobacterium. The isolate therefore represents a novel species, for which the name Phenylobacterium aquaticum sp. nov. is proposed, with the type strain W2-3-4(T) (=KACC 18306(T) =LMG 28593(T)).