Roseateles depolymerans gen, nov., sp. nov., a new bacteriochlorophyll a-containing obligate aerobe belonging to the beta-subclass of the Proteobacteria

Strains 61A(T) (T = type strain) and 61B2, the first bacteriochlorophyll (B Chl) a-containing obligate aerobes to be classified in the beta-subclass of the Proteobacteria, were isolated from river water. The strains were origi nally isolated as degraders of poly(hexamethylene carbonate) (PHC), The org anisms can utilize PHC and some other biodegradable plastics. The strains g row only under aerobic conditions. Good production of BChl a and carotenoid pigments is achieved on PHC agar plates and an equivalent production is ob served under oligotrophic conditions on agar medium. Spectrometric results suggest that BChl a is present in light-harvesting complex I and the photoc hemical reaction centre. The main carotenoids are spirilloxanthin and its p recursors. Analysis of the 16S rRNA gene sequence indicated that the phylog enetic positions of the two strains are similar to each other and that thei r closest relatives are the genera Rubrivivax, Ideonella and Leptothrix wit h similarities of 96.3, 96.2 and 96.1%, respectively, The cells are motile, straight rods and contain poly-beta-hydroxybutyrate granules. Ubiquinone-8 is the predominant quinone, Vitamins are not required for growth. The G+C content of genomic DNA is 66.2-66.3 mol%, Genetic and phenotypic features s uggest that the strains represent a new genus in the beta-subclass which is evenly distant from known genera. Consequently, the name Roseateles depoly merans gen. nov., sp. nov. is proposed for the strains; the type strain of Roseateles depolymerans is strain 61A(T) (= DSM 11813(T)).