Reclassification of Rhodospirillum photometricum Molisch 1907, Rhodospirillum sulfurexigens Anil Kumar et al. 2008 and Rhodospirillum oryzae Lakshmi et al. 2013 in a new genus, Pararhodospirillum gen. nov., as Pararhodospirillum photometricum comb. nov., Pararhodospirillum sulfurexigens comb. nov. and Pararhodospirillum oryzae comb. nov., respectively, and emended description of the genus Rhodospirillum.

The genus Rhodospirillum is represented by four species, with three of them showing phylogenetic divergence compared to the type species, Rhodospirillum rubrum. Differences in the major diagnostic properties such as internal photosynthetic membranes, quinones, fatty acids, carotenoid composition and a few other phenotypic properties warrant the reclassification of members of this genus. Resultantly, a new genus, Pararhodospirillum gen. nov., is proposed based on the analysis of nine strains to accommodate Rhodospirillum photometricum, Rhodospirillum sulfurexigens and Rhodospirillum oryzae as Pararhodospirillum photometricum comb. nov., Pararhodospirillum sulfurexigens comb. nov. and Pararhodospirillum oryzae comb. nov., respectively. The type species of the genus is Pararhodospirillum photometricum comb. nov. An emended description of the genus Rhodospirillum is also proposed.

Rhodopseudomonas pentothenatexigens sp. nov. and Rhodopseudomonas thermotolerans sp. nov., isolated from paddy soils.

Two strains (JA575(T) and JA576(T)) of orange- to pink-pigmented, rod-shaped, motile and budding phototrophic bacteria were isolated from paddy soils. Both strains contained bacteriochlorophyll a and carotenoids of spirilloxanthin series. Both strains had C(18 : 1)ω7c as the major cellular fatty acid, ubiquinone-10 (Q(10)) as the main quinone, and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine as polar lipids. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that both strains clustered with species of the genus Rhodopseudomonas in the class Alphaproteobacteria. Strains JA575(T) and JA576(T) were genotypically (<35 % DNA-DNA relatedness) and phenotypically distinct from each other. Further, both strains showed less than 48 % DNA-DNA relatedness with the type strains of all recognized species of the genus Rhodopseudomonas. The molecular evidence is supported by phenotypic evidence. It is proposed that strains JA575(T) and JA576(T) be classified as representing two novel species of the genus Rhodopseudomonas with the species names Rhodopseudomonas pentothenatexigens sp. nov. and Rhodopseudomonas thermotolerans sp. nov., respectively. The type strains of the proposed novel species are JA575(T) (= NBRC 108862(T) = KCTC15143(T)) and JA576(T) (= NBRC 108863(T) = KCTC 15144(T)), respectively.

Blastochloris gulmargensis sp. nov., isolated from an epilithic phototrophic biofilm.

A novel Gram-negative, motile, bacteriochlorophyll b-containing purple non-sulfur bacterium, strain JA248(T), was isolated from phototrophic enrichments of a yellow-green epilithic biofilm sample collected from Gulmarg, India. The genomic DNA G+C content of strain JA248(T) was 63.8 mol%. A phylogenetic tree based on 16S rRNA gene sequence analysis showed that strain JA248(T) had highest similarity to members of the genus Blastochloris and was closely related to Blastochloris sulfoviridis DSM 729(T) (98.5 % sequence similarity) and Blastochloris viridis DSM 133(T) (98.4 %) of the class Alphaproteobacteria. Strain JA248(T) was characterized based on polyphasic taxonomy, and distinct phenotypic and molecular differences based on DNA-DNA hybridization (relatedness of <46.5 % with the two species of the genus Blastochloris), multilocus sequence analysis, and phenotypic and chemotaxonomic evidence separated strain JA248(T) from other species of the genus Blastochloris. Strain JA248(T) therefore represents a novel species in the genus Blastochloris, for which the name Blastochloris gulmargensis sp. nov. is proposed. The type strain is JA248(T) ( = JCM 14795(T)  = DSM 19786(T)).