Rhodobacter megalophilus sp. nov., a phototroph from the Indian Himalayas possessing a wide temperature range for growth

Abstract

Two strains of phototrophic, purple non-sulfur bacteria capable of growing at low temperatures (5 6C) were isolated from the Himalayas. The two strains showed positive phototaxis and grew over a relatively wide temperature range (5-40 6C). Phylogenetic analysis based on 16S rRNA gene sequences showed that strain JA194T clustered with members of the genus Rhodobacter. ) is sufficiently different from other Rhodobacter species to merit its description as the type strain of a novel species, for which the name Rhodobacter megalophilus sp. nov. is proposed.The genus Rhodobacter includes both motile and nonmotile species. Motile species of the genus have a single polar flagellum and those that lack flagellar motility include Rhodobacter veldkampii (Imhoff, 2005), Rba. vinaykumarii (Srinivas et al., 2007c), Rba. changlensis and Rba. ovatus (Srinivas et al., 2008). Rba. changlensis, a phototrophic bacterium from the Indian Himalayan region, was recently described by our group . In the present communication, we propose a novel species of this genus isolated from the Indian Himalayas, which has properties distinct from all other Rhodobacter species based on phenotypic and phylogenetic analysis. Strain JA194T was isolated from a soil sample collected from Suraj tal near Sarchu [34u 179 N 77 u 589 E, 11 975 feet (3650 m) above sea level], in the Indian Himalayas. Strain JA247 was isolated from a soil sample collected from an army camp located at Kargil, Ladakh [34u 179 N 77 u 559 E, 18 050 feet (5502 m) above sea level], in the Himalayas. Purification of the strains and polyphasic study for their taxonomic characterization were performed as described by Srinivas et al. (2007a). For dendrogram construction, sequences were aligned by using the program CLUSTAL_X (Thompson et al., 1997) and the alignment was corrected manually. Phylogenetic analysis was carried out by using the PHYLIP package, version 3.5 (Felsenstein, 1993). The evolutionary distance matrix was calculated according to the distance model of Jukes & Cantor (1969). The evolutionary tree was constructed by using the neighbour-joining method (Saitou & Nei, 1987) and the resultant tree topologies were evaluated by bootstrap analysis based on 100 resamplings via the SEQBOOT and CONSENSE programs in the PHYLIP package.For metabolome fingerprinting, exponentially growing photoheterotrophic cultures were harvested by centrifugation (15 000 r.p.m. for 15 min for reference strain Rba. sphaeroides DSM 158 T ; 35 000 r.p.m. for 30 min for strains JA194T and JA247) and the resultant pellets were washed Abbreviation: FT-IR, Fourier transform infrared.The GenBank/EMBL/DDBJ accession numbers for the 16S rRNA gene sequences of strains JA194 T and JA247 are AM421024 and AM421806, respectively. Phase-contrast micrographs of cells of strain JA194T and FT-IR fingerprint analysis of the endometabolome and lipids of strain JA194 T and Rba. sphaeroides DSM 158 T are available as supplementary material with the online version of this paper.

Efficient Ammonium Removal by Bacteria Rhodopseudomonas Isolated from Natural Landscape Water: China Case Study

“…Within the temperature range of 10-50 • C, Smobiisys501 grew better at higher temperatures, but when the temperature reached 35 • C, bacterial growth decreased. The optimal growth temperature of Smobiisys501 was about 30 • C (Figure 4a), which was consistent with the reported strain of the genus Rhodopseudomonas [30]. In this study, the growth of Smobiisys501 was affected by the pH, like in previous studies [31,32].…”

“…In order to obtain the optimal growth conditions of Smobiisys501, three cultivation conditions which affect the growth of Smobiisys501 including temperature (10,20,30,35,40,45, and 50 • C), pH (4, 5, 6, 7, 8, 9, and 10), and nitrogen source (nitrate (LiNO 3 , NaNO 3 , KNO 3 ), ammonium (CH 3 COONH 4 , NH 4 Cl, (NH 4 ) 2 C 2 O 4 ), (NH 4 ) 2 SO 4 ), organic nitrogen (urea, peptone, and yeast extract)) were determined [22]. The pH value of raw water was adjusted to desirable values using 0.1 M NaOH or 0.1 M HCl.…”

Rhodobacter johrii sp. nov., an endospore-producing cryptic species isolated from semi-arid tropical soils

“…megalophilus JA194 T from Rba. sphaeroides DSM 158 T (Arunasri et al, 2008) and Rubrivivax benzoatilyticus from Rubrivivax gelatinosus (Ramana et al, 2006). Other pairs of closely related phototrophic species with nearly 99 % 16S rRNA gene sequence similarity, such as Phaeospirillum molischianum and Phaeospirillum fulvum (Imhoff et al, 1998a), Allochromatium minutissimum and Allochromatium vinosum (Imhoff et al, 1998b) and Blastochloris sulfoviridis and Blastochloris viridis (Hiraishi, 1997), have been maintained due to characteristic phenotypic differences.…”

“…maris (Venkata Ramana et al, 2008), Rba. megalophilus (Arunasri et al, 2008) and Rba. aestuarii (Anil Kumar et al, 2009).…”

Catellibacterium aquatile sp. nov., isolated from fresh water, and emended description of the genus Catellibacterium Tanaka et al. 2004

“…At the time of writing, the genus includes only one species, Catellibacterium nectariphilum, which was isolated from activated sludge and requires a diffusible compound from other bacterial cultures for vigorous growth (Tanaka et al, 2004). Since 2008, many novel bacteria belonging to 'Rhodobacter clade' have been isolated from various environments, such as Rhodobacter megalophilus from soil (Arunasri et al, 2008), Rhodobacter maris and Rhodobacter aestuarii from marine environments , 2009, Rhodobacter ovatus from a polluted pond , Rhodovulum kholense from mud (Anil , Rhodovulum lacipunicei (Chakravarthy et al, 2009), Paracoccus halophilus from marine sediment (Liu et al, 2008), Paracoccus aestuarii from tidal-flat sediment (Roh et al, 2009), Paracoccus saliphilus from a salt lake (Wang et al, 2009) and Rhodobaca barguzinensis from sediments of a soda lake (Boldareva et al, 2008). Their wide distribution and metabolic diversity (such as heterotrophic, phototrophic and chemically autotrophic metabolism) suggest that members of this clade may play important roles in various ecosystems, especially aquatic environments.…”