TABLE 1.
Differentiating characters of taxa of the genus Rhodobacter and closely related genera of the family ‘Rhodobacteraceae.’
| Characteristic | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 |
| Cell shape | R-O | R-O | R-O | R-O | R | R-O | R | R-O | R | R,O | R | R-O | R | C-R |
| Motility | ± | + | – | – | – | – | ± | ± | – | ± | – | ± | ± | ± |
| Phototrophic growth | + | + | + | + | + | + | – | – | – | – | – | + | – | – |
| Multiplication | Binary fission | Binary fission | Sessile budding | Binary fission | Binary fission | Binary fission | Binary fission | Binary fission/Budding | nd | nd | Binary fission | Binary fission | nd | Binary fission |
| Slime production | ± | ± | – | – | + | + | – | nd | nd | nd | nd | ± | nd | |
| Growth at 5°C | ± | – | – | – | – | + | – | ± | – | – | + | nd | – | ± |
| Vitamins | b,n,t | b,n,t | n,t,b | b,paba,t | b | b,n,t | – | b,n,t,paba,B3,B12 | nd | nd | b,n,t,paba,B3 | b,n,t,paba, B12, complex | B3,B12 | nd |
| NaCl requirement | – | – | – | – | + | – | + | ± | + | + | – | ± | – | + |
| Sulfate assimilation | + | + | + | – | + | + | nd | nd | nd | nd | nd | ± | – | – |
| Denitrification | ± | – | – | – | – | – | – | ± | – | ±∗ | – | – | – | ± |
| BChl-a | + | + | + | + | + | + | – | – | – | – | – | + | – | – |
| IMA | Vesicles | Vesicles | Lamellar | Vesicles | Vesicles | Vesicles | – | – | – | – | – | Vesicles | – | – |
| Production of carotenoids | + | + | + | + | + | + | – | – | – | – | – | + | – | – |
| Light harvesting complexes | LH1,LH2 | LH1,LH2 | LH1,LH2 | LH1,LH2 | LH1,LH2 | LH1,LH2 | – | – | – | – | – | LH1,LH2 | – | – |
| Photoautotrophic growth | ± | ± | + | + | – | – | – | – | – | – | – | ± | – | – |
| Dark anaerobic growth | ± | ± | – | nd | – | + | – | – | – | – | – | ± | – | – |
| Fatty acids | ||||||||||||||
| C18:03OH | – | + | nd | – | – | – | – | + | – | ± | – | – | – | ± |
| C18:1ω7c11 methyl | + | – | – | + | + | ± | ± | – | ± | – | + | + | ± | |
| Polar lipids | ||||||||||||||
| GL | + | – | – | – | – | + | + | ± – | – | – | – | – | nd | + |
| SL | – | – | – | – | – | – | – | – | – | – | – | + | – | |
| PC | + | + | + | – | + | + | + | + | – | + | – | – | + | |
| DPG | + | – | – | – | – | + | + | ± | – | – | – | – | + | |
| Isolation source | Fresh, soil | Fresh and Marine | Freshwater | Freshwater | Marine | Snow sample | Soil, Slattern | Freshwater | Blood, Nose | Marine | Soil | Hyper-saline and marine | Marine | Soil, sewage |
(1) Rhodobacter sphaeroides clade (Rba. sphaeroides, Rba. johrii, Rba. megalophilius, Rba. azotoformans, Rba. ovatus and Rba. alkalitolerans; data from this study, Hiraishi et al., 1996; Imhoff, 2005; Arunasri et al., 2008; Srinivas et al., 2008; Girija et al., 2010; Gandham et al., 2018); (2) Rhodobacter sensu stricto clade (Rba. capsulatus, Rba. aestuarii, Rba. maris, Rba. viridis, Rba. sediminis, Rba. lacus and Rba. azollae; data from this study and from Imhoff, 2005; Venkata Ramana et al., 2009; Girija et al., 2010; Shalem Raj et al., 2013; Subhash and Lee, 2016; Suresh et al., 2017); (3) Rhodobacter blasticus clade (Rba. blasticus; data from this study, data taken from Eckersley and Dow, 1980; Girija et al., 2010); (4) Rhodobacter veldkampii clade (Rba. veldkampii; data from this study, data taken from Hansen and Imhoff, 1985; Girija et al., 2010); (5) Rba. vinaykumarii clade (Rba. vinaykumarii; data from this study, data taken from Srinivas et al., 2007; Girija et al., 2010); (6) Cereibacter (Cer. changlensis; data taken from Girija et al., 2010; Suresh et al., 2015); (7) Falsirhodobacter (F. deserti, F. halotolerans; data taken from Subhash et al., 2013; Wang et al., 2015); (8) Gemmobacter (10 species; data taken from Rothe et al., 1987; Chen C.X. et al., 2013; Sheu et al., 2013; Liu et al., 2014; Kämpfer et al., 2015; Suresh et al., 2015); (9) Haematobacter (H. missouriensis, H. massiliensis; data taken from Helsel et al., 2007; Subhash et al., 2013; Wang et al., 2014); (10) Pseudorhodobacter (four strains, data taken from Uchino et al., 2002; Jung et al., 2012; Chen W.M. et al., 2013; Lee et al., 2013; Zhang et al., 2016); (11) Paenirhodobacter (P. enshiensis; data taken from Wang et al., 2014); (12) Rhodovulum (based on nineteen species including the recently described Rdv. aestuarii; data taken from Lakshmi et al., 2011; Srinivas et al., 2012, 2014; Nupur et al., 2014; Divyasree et al., 2015; Suresh et al., 2015); (13) Pararhodobacter (P. aggregans; data taken from Foesel et al., 2011; Xie et al., 2015); (14) Paracoccus (based on 41 species; data taken from Kämpfer et al., 2012; Sun et al., 2013; Pan et al., 2014; Zhang et al., 2014). R-O, rod to oval; R, rod; C-R, coccoid to rod; b, Biotin; B12, vitamin B12; B3, vitamin B3; n, niacin; paba, p-aminobenzoic acid; t, thiamine; PC, Phosphatidylcholine; SL, Sulfolipid; GL, Glycolipid; DPG, Diphosphatidylglycerol; LH, light harvesting system; +, present; −, absent; ∗, data of nitrate reduction; nd, No data available; IMA, Internal membrane architecture.