Hydrogenophaga caeni sp. nov., isolated from activated sludge.

A Gram-negative bacterium, designated strain EMB71(T), was isolated from activated sludge used for enhanced biological phosphorus removal in a sequencing batch reactor. The cells of the isolate were facultatively aerobic, motile rods with single polar flagella. Growth was observed to occur at 15-35 degrees C (optimally at 30 degrees C) and at pH 6.0-9.0 (optimally at pH 7.0-8.0). The predominant fatty acids of strain EMB71(T) were C(16 : 0) and summed feature 3 (C(16 : 1)omega7c and/or iso-C(15 : 0) 2-OH), and the polar lipids comprised a large amount of phosphatidylethanolamine and a small amount of diphosphatidylglycerol. The G+C content of the genomic DNA was 61.6 mol % and the major quinone was Q-8. Comparative 16S rRNA gene sequence analyses showed that strain EMB71(T) formed a phyletic lineage with the genus Hydrogenophaga within the family Comamonadaceae. The levels of 16S rRNA gene sequence similarity with respect to the type strains of Hydrogenophaga species ranged from 95.1 to 96.9 %. On the basis of the phenotypic, chemotaxonomic and molecular data, strain EMB71(T) represents a novel species of the genus Hydrogenophaga, for which the name Hydrogenophaga caeni sp. nov. is proposed. The type strain is EMB71(T) (=KCTC 12613(T)=DSM 17962(T)).