Descriptions of Rhodopseudomonas parapalustris sp. nov., Rhodopseudomonas harwoodiae sp. nov. and Rhodopseudomonas pseudopalustris sp. nov., and emended description of Rhodopseudomonas palustris.

ABSTRACT

Four strains (JA310(T), JA531(T), JA447 and JA490) of red to reddish brown pigmented, rod-shaped, motile and budding phototrophic bacteria were isolated from soil and freshwater sediment samples from different geographical regions of India. All strains contained bacteriochlorophyll a and carotenoids of the spirilloxanthin series. The major cellular fatty acid of strains JA310(T) and JA531(T) was C(181)ω7c, the quinone was Q-10 and polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an aminohopanoid and an unidentified aminolipid. Phylogenetic analysis based on 16S rRNA gene sequences showed that all strains clustered with species of the genus Rhodopseudomonas in the class Alphaproteobacteria. Strains JA531(T), JA447 and JA490 were genotypically (>80% related based on DNA-DNA hybridization) and phenotypically closely related to each other and the three strains were distinct from strain JA310(T) (33% related). Furthermore, all four strains had less than 48% relatedness (DNA-DNA hybridization) with type strains of members of the genus Rhodopseudomonas, i.e. Rhodopseudomonas palustris ATCC 17001(T), Rhodopseudomonas faecalis JCM 11668(T) and Rhodopseudomonas rhenobacensis DSM 12706(T). The genomic DNA G+C contents of strains JA310(T) and JA531(T) were 63.8 and 62.4 mol%, respectively. On the basis of phenotypic, chemotaxonomic and molecular genetic evidence, it is proposed that strains JA310(T) ( = NBRC 106083(T) = KCTC 5839(T)) and JA531(T) ( = NBRC 107575(T) = KCTC 5841(T)) be classified as the type strains of two novel species of the genus Rhodopseudomonas, Rhodopseudomonas parapalustris sp. nov. and Rhodopseudomonas harwoodiae sp. nov., respectively. In addition, we propose that strain DSM 123(T) ( = NBRC 100419(T)) represents a novel species, Rhodopseudomonas pseudopalustris sp. nov., since this strain differs genotypically and phenotypically from R. palustris ATCC 17001(T) and other members of the genus Rhodopseudomonas. An emended description of R. palustris is also provided.