Abstract
The taxonomy of strain KF46F(T), which was isolated previously after an aerobic enrichment with the azo compound 1-(4'-carboxyphenylazo)-2-naphthol as the sole source of energy and carbon, was investigated by a polyphasic approach. The organism contained a quinone system with ubiquinone Q-8 and 2-hydroxyputrescine and putrescine as the major polyamines, suggesting that strain KF46F(T) belonged to the beta-subclass of the Proteobacteria. The polar lipid profile consisted mainly of phosphatidylethanolamine and minor amounts of phosphatidylglycerol and diphosphatidylglycerol. Sequencing of the 16S rRNA gene supported its placement in the family Comamonadaceae, but the sequence similarities to the most closely related species of the genera Hydrogenophaga, Acidovorax, Comamonas and Xylophilus were only in the range 95.0 to 96.1%. Different methods for the construction of phylogenetic trees showed the separate position of strain KF46F(T) 'between' the genera Hydrogenophaga, Variovorax, Comamonas and Xylophilus. Analysis of the fatty acids revealed an unusual profile, with the presence of 8:0 3-OH, 10:0 3-OH, 16:1 2-OH, 16:0 2-OH and 18:1 2-OH in addition to 17:0 cyclo, which is unique among the previously described genera of the family Comamonadaceae. Thus, a new taxon is proposed for strain KF46F(T), with the name Xenophilus azovorans gen. nov., sp. nov.