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Two bacterial strains, designated HSP-20 T and CCP-1 T , isolated from freshwater habitats in Taiwan, were characterized by polyphasic taxonomy. Both strains were Gram-stain-negative, aerobic, non-motile and rod-shaped. Cells of strains HSP-20 T and CCP-1 T formed pink and dark red coloured colonies, respectively. Both strains contained bacteriochlorophyll a , and showed optimum growth under anaerobic conditions by photoheterotrophy, but no growth by photoautotrophy. Phylogenetic analyses based on 16S rRNA gene and whole-genome sequences indicated that both strains belonged to the genus Rhodobacter . Analysis of 16S rRNA gene sequences showed that strains HSP-20 T and CCP-1 T shared 98.3 % sequence similarity and were closely related to Rhodobacter tardus CYK-10 T (96.0 %) and Rhodobacter flagellatus SYSU G03088 T (96.0 %), respectively. Both strains shared common chemotaxonomic characteristics including Q-10 as the major isoprenoid quinone, C 18 : 1  ω 7 c as the predominant fatty acid, and phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine as the main polar lipids. The DNA G+C content of both strains was 66.2 mol%. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between these two novel isolates and their closest relatives were below the cut-off values of 95-96, 90 and 70 %, respectively, used for species demarcation. On the basis of phenotypic and genotypic properties and phylogenetic inference, both strains should be classified as novel species within the genus Rhodobacter , for which the names Rhodobacter amnigenus sp. nov. (=BCRC 81193 T =LMG 31334 T ) and Rhodobacter ruber sp. nov. (=BCRC 81189 T =LMG 31335 T ) are proposed.

Two Gram-stain-negative, aerobic, non-motile bacteria, designated KMS-5 T and CYK-10 T , were isolated from freshwater environments. 16S rRNA gene sequence similarity results indicated that these two novel strains belong to the family Rhodobacteraceae . Strain KMS-5 T is closely related to species within the genus Tabrizicola (96.1-96.8 % sequence similarity) and Cypionkella (96.5-97.0 %). Strain CYK-10 T is closest to Rhodobacter thermarum YIM 73036 T with 96.6 % sequence similarity. Phylogenetic analyses based on 16S rRNA gene sequences and an up-to-date bacterial core gene set showed that strain KMS-5 T is affiliated with species in the genus Tabrizicola and strain CYK-10 T is placed in a distinct clade with Rhodobacter blasticus ATCC 33485 T , Rhodobacter thermarum YIM 73036 T and Rhodobacter flagellatus SYSU G03088 T . These two strains shared common chemotaxonomic features comprising Q-10 as the major quinone, phosphatidylethanolamine, phosphatidylglycerol and phosphatidylcholine as the principal polar lipids, and C 18 : 1  ω 7 c as the main fatty acid. The average nucleotide identity, average amino acid identity and digital DNA-DNA hybridization values between these two novel isolates and their closest relatives were below the cut-off values of 95-96, 90 and 70 %, respectively, used for species demarcation. The obtained polyphasic taxonomic data suggested that strain KMS-5 T represents a novel species within the genus Tabrizicola , for which the name Tabrizicola oligotrophica sp. nov. is proposed with KMS-5 T (=BCRC 81196 T =LMG 31337 T ) as the type strain, and strain CYK-10 T should represent a novel species of the genus Rhodobacter , for which the name Rhodobacter tardus sp. nov. is proposed with CYK-10 T (=BCRC 81191 T =LMG 31336 T ) as the type strain.

An ovoid to rod-shaped, phototrophic, purple non-sulfur bacterium was isolated from a brown-coloured microbial mat from the brackish water of Bhitarkanika mangrove forest, Dangmal, Orissa, India. Cells of strain JA296(T) were Gram-negative and motile, forming chains of four to eight cells. The colour of the cell suspension grown under anaerobic conditions in the light was yellowish green. Bacteriochlorophyll a and the carotenoids spheroidene and spheroidenone of the spirilloxanthin series were present as photosynthetic pigments. The bacterium was a facultative anaerobe and was able to grow photo-organoheterotrophically and chemo-organoheterotrophically. Thiamine was required as a growth factor. C(18 : 1)omega7c was the dominant fatty acid. Internal cytoplasmic membranes were of the vesicular type. Strain JA296(T) did not require NaCl for growth. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA296(T) was most closely related to Rhodobacter capsulatus ATCC 11166(T) (95.5 % sequence similarity) and clustered with species of the genus Rhodobacter of the family Rhodobacteraceae, class Alphaproteobacteria. On the basis of 16S rRNA gene sequence analysis and morphological and physiological characteristics, strain JA296(T) represents a novel species of the genus Rhodobacter, for which the name Rhodobacter aestuarii sp. nov. is proposed; the type strain is JA296(T) (=JCM 14887(T) =CCUG 55130(T)).

A novel ovoid, phototrophic, purple non-sulfur bacterium was isolated in pure culture from a sample of sediment from an industrially polluted pond (Noor Mohammad Kunta) in Hyderabad, India. Strain JA234(T) was found to be Gram-negative and non-motile and grew photoheterotrophically with a number of organic compounds serving as carbon source/electron donor. Photo-organoheterotrophic and chemo-organoheterotrophic growth were demonstrated. Biotin and thiamine were required for growth of strain JA234(T). Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA234(T) is most closely related to Rhodobacter azotoformans (97.3 % sequence similarity) and clusters with other species of the genus Rhodobacter of the family Rhodobacteraceae. However, DNA-DNA hybridization with Rba. azotoformans JCM 9340(T) showed a relatedness of only 31.3 % with respect to strain JA234(T). On the basis of 16S rRNA gene sequence analysis, DNA-DNA hybridization data and morphological and physiological characteristics, strain JA234(T) represents a novel species of the genus Rhodobacter, for which the name Rhodobacter ovatus sp. nov. is proposed. The type strain is JA234(T) (=JCM 14779(T)=CCUG 55049(T)).