Search

The genus Jannaschia is one of the representatives of aerobic anoxygenic phototrophic (AAP) bacteria, which is a strictly aerobic bacterium, producing a photosynthetic pigment bacteriochlorophyll (BChl) a. However, a part of the genus Jannaschia members have not been confirmed the photosynthetic ability. The partly presence of the ability in the genus Jannaschia could suggest the complexity of evolutionary history for anoxygenic photosynthesis in the genus, which is expected as gene loss and/or horizontal gene transfer. Here a novel AAP bacterium designated as strain AI_62 T (= DSM 115720  T  = NBRC 115938  T ), was isolated from coastal seawater around a fish farm in the Uwa Sea, Japan. Its closest relatives were identified as Jannaschia seohaensis SMK-146  T (95.6% identity) and J. formosa 12N15 T (94.6% identity), which have been reported to produce BChl a. The genomic characteristic of strain AI_62 T clearly showed the possession of the anoxygenic photosynthesis related gene sets. This could be a useful model organism to approach the evolutionary mystery of anoxygenic photosynthesis in the genus Jannaschia. Based on a comprehensive consideration of both phylogenetic and phenotypic characteristics, we propose the classification of a novel species within the genus Jannaschia, designated as Jannaschia pagri sp. nov. The type strain for this newly proposed species is AI_62 T (= DSM 115720  T  = NBRC 115938  T )., (© 2024. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

How atoms and electrons in a molecule move during a chemical reaction and how rapidly energy is transferred to or from the surroundings can be studied with flashes of laser light. However, despite prolonged efforts to develop various coherent spectroscopic techniques, the lack of an all-encompassing method capable of both femtosecond time resolution and nanosecond relaxation measurement has hampered various applications of studying correlated electron dynamics and vibrational coherences in functional materials and biological systems. Here, we demonstrate that two broadband (>300 nm) synchronized mode-locked lasers enable two-dimensional electronic spectroscopy (2DES) study of chromophores such as bacteriochlorophyll a in condensed phases to measure both high-resolution coherent vibrational spectrum and nanosecond electronic relaxation. We thus anticipate that the dual mode-locked laser-based 2DES developed and demonstrated here would be of use for unveiling the correlation between the quantum coherence and exciton dynamics in light-harvesting protein complexes and semiconducting materials.

Here, we report the first description of a marine purple sulfur bacterium (PSB) from sulfide-rich sediments of a marine mangrove in the Caribbean. TEM shows that this new isolate contains intracytoplasmic vesicular membrane systems (containing bacteriochlorophyll a) and larger internal sulfur granules, confirmed by EDXS analyses performed using ESEM. The sulfur distribution and mapping obtained for this PSB strain has allowed us to conclude that elemental sulfur is formed as an intermediate oxidation product and stored intracellularly. SEM shows that the bacterial cells are ovoid and extremely motile via lophotrichous flagella. Phylogenetic characterization, based on the analysis of 16S rDNA and functional gene pufM sequences, demonstrate that this strain belongs to the Chromatiaceae and may be a representative of a new species of the genus Halochromatium. Thus, reduced sediments of marine mangrove represent a sulfide-rich environment that sustains the development of Chromatiaceae, in addition to sulfur-oxidizing bacteria and cyanobacteria, as previously reported., (Copyright © 2018. Published by Elsevier Masson SAS.)

The molar extinction coefficients of light-harvesting complex 2 (LH2) have been ambiguous in spite of its fame and wide utilization. Herein we determine the molar extinction coefficients of the LH2 proteins derived from the three purple photosynthetic bacteria Rhodoblastus acidophilus, Rhodobacter sphaeroides and Phaeospirillum molischianum at 298 K by direct extraction of bacteriochlorophyll (BChl) a from the lyophilized proteins, followed by estimation of BChl a amounts from their electronic absorption spectra.

Most purple photosynthetic bacteria contain bacteriochlorophyll(BChl)-a (a magnesium complex) and bacteriopheophytin(BPhe)-a (its free base) as their photoactive pigments. These pigments are composed of two parts: a cyclic tetrapyrrole as the chromophore and a long hydrocarbon-chain as the propionate-type esterifying group at the 17-position. The hydrocarbon-chain is usually an isoprenoid-type C20 phytyl (Phy) group in both the pigments. In the ester group of BChl-a, several variants such as geranylgeranyl (GG), dihydrogeranylgeranyl (DHGG) and tetrahydrogeranylgeranyl (THGG) groups were found in the final stage of BChl-a biosynthesis. On the other hand, the esterifying variants in BPhe-a have not been studied as much due to the lower levels of this pigment relative to BChl-a. The esterifying group does not affect the electronic absorption properties of such pigments in the monomeric state, but drastically alters the hydrophobicity. In this study, BChl-a and BPhe-a in the six phylogenetically distinct classes of purple bacteria were analyzed in terms of their esterifying groups in the 17-propionate residues, using high-performance liquid chromatography. Both BChls-a and BPhes-a carrying GG, DHGG and THGG in addition to the usual Phy were found for all the bacterial species studied at measurable levels. In some of the species, the ratio of BPhes-a esterified with GG, DHGG and THGG over the total BPhe-a drastically decreased in comparison with that of the corresponding BChls-a. Especially, the relative content of BPhe-a with GG largely decreased. This observation might indicate that BPhe-a as a cofactor of reaction centers was preferentially esterified with partially reduced and flexible chains (THGG and Phy) rather than less reduced and rigid ones (GG and DHGG)., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Reaction center-light harvesting 1 (RC-LH1) complexes are the fundamental units of bacterial photosynthesis, which use solar energy to power the reduction of quinone to quinol prior to the formation of the proton gradient that drives ATP synthesis. The dimeric RC-LH1-PufX complex of Rhodobacter sphaeroides is composed of 64 polypeptides and 128 cofactors, including 56 LH1 bacteriochlorophyll a (BChl a) molecules that surround and donate energy to the two RCs. The 3D structure was determined to 8 Å by X-ray crystallography, and a model was built with constraints provided by electron microscopy (EM), nuclear magnetic resonance (NMR), mass spectrometry (MS), and site-directed mutagenesis. Each half of the dimer complex consists of a RC surrounded by an array of 14 LH1 αβ subunits, with two BChls sandwiched between each αβ pair of transmembrane helices. The N- and C-terminal extrinsic domains of PufX promote dimerization by interacting with the corresponding domains of an LH1 β polypeptide from the other half of the RC-LH1-PufX complex. Close contacts between PufX, an LH1 αβ subunit, and the cytoplasmic domain of the RC-H subunit prevent the LH1 complex from encircling the RC and create a channel connecting the RC QB site to an opening in the LH1 ring, allowing Q/QH₂ exchange with the external quinone pool. We also identified a channel that connects the two halves of the dimer, potentially forming a long-range pathway for quinone migration along rows of RC-LH1-PufX complexes in the membrane. The structure of the RC-LH1-PufX complex explains the crucial role played by PufX in dimer formation, and it shows how quinone traffic traverses the LH1 complex as it shuttles between the RC and the cytochrome bc₁ complex.

Aerobic anoxygenic photosynthesis (AAP) is found in an increasing number of proteobacterial strains thriving in ecosystems ranging from extremely oligotrophic to eutrophic. Here, we have investigated whether the fuel oxygenate-degrading betaproteobacterium Aquincola tertiaricarbonis L108 can use AAP to compensate kinetic limitations at low heterotrophic substrate fluxes. In a fermenter experiment with complete biomass retention and also during chemostat cultivation, strain L108 was challenged with extremely low substrate feeding rates of tert-butyl alcohol (TBA), an intermediate of methyl tert-butyl ether (MTBE). Interestingly, formation of photosynthetic pigments, identified as bacteriochlorophyll a and spirilloxanthin, was only induced in growing cells at TBA feeding rates less than or equal to maintenance requirements observed under energy excess conditions. Growth continued at rates between 0.001 and 0.002 h(-1) even when the TBA feed was decreased to values close to 30 % of this maintenance rate. Partial sequencing of genomic DNA of strain L108 revealed a bacteriochlorophyll synthesis gene cluster (bchFNBHL) and photosynthesis regulator genes (ppsR and ppaA) typically found in AAP and other photosynthetic proteobacteria. The usage of light as auxiliary energy source enabling evolution of efficient degradation pathways for kinetically limited heterotrophic substrates and for lowering the threshold substrate concentration Smin at which growth becomes zero is discussed.

A reddish-brown bacterium, designated strain JA318(T), was purified from a photoheterotrophic enrichment culture obtained from the rhizosphere soil of paddy. Cells of strain JA318(T) are spiral shaped, Gram-stain-negative and motile by means of amphitrichous flagella. Strain JA318(T) has no NaCl requirement for growth but can tolerate up to 1.5 % (w/v) NaCl. Internal photosynthetic membranes are present as lamellar stacks. Photoorganoheterotrophy is the only growth mode observed. Strain JA318(T) contains bacteriochlorophyll a, lycopene and rhodopin as major carotenoids. Thiamine, niacin and para-aminobenzoic acid (PABA) are required as growth factors. Major fatty acids are C18 : 1ω7c and C16 : 0. Ubiquinone-8 and rhodoquinone-8 are the observed quinones. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and an unidentified aminolipid are the major polar lipids in strain JA318(T). Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain JA318(T) clustered with species of the genus Rhodospirillum which belongs to the class Alphaproteobacteria. The highest sequence similarity of strain JA318(T) was found with Rhodospirillum sulfurexigens JA143(T) (99.9 %). The DNA-DNA reassociation values of strain JA318(T) with Rsp. sulfurexigens JA143(T) and Rhodospirillum photometricum DSM 122(T) were 52 ± 2 % and 45 ± 1 %, respectively. The genomic DNA G+C content of strain JA318(T) was 60.2 mol%. Based on the morphological, physiological, chemotaxonomical and molecular evidence, strain JA318(T) is significantly different from the type strains of species of the genus Rhodospirillum, of the family Rhodospirillaceae, and it is proposed that the strain be classified as a representative of a novel species for which the name Rhodospirillum oryzae sp. nov. is proposed. The type strain is JA318(T) (= KCTC 5960(T) = NBRC 107573(T)).

Two strains (JA643(T) and JA755) of Gram-stain-negative, facultatively anaerobic phototrophic, bacteria capable of growth at low temperatures (10-15 °C) were isolated from freshwater streams from different geographical regions of India. Both strains contain bacteriochlorophyll a and carotenoids of the spirilloxanthin series. Phosphatidylethanolamine, phosphatidylcholine, phosphatidylglycerol, diphosphatidylglycerol, an unidentified phospholipid (PL), unidentified amino lipids (AL1-AL6, AL9) and an unidentified lipid (L1) were the polar lipids present in both strains. The major cellular fatty acid was C18 : 1ω7c (76-79 % of the total). Bacteriohopane derivatives (BHD1,2), unidentified hopanoids (UH1-5), diplopterol (DPL) and diploptene (DPE) were the major hopanoids of both strains. The DNA G+C content was 64.2-64.5 mol%. 16S rRNA gene sequence-based phylogenetic analysis showed that both strains are closely related to the genus Rhodomicrobium and clustered with Rhodomicrobium vannielii DSM 162(T) (99 % sequence similarity). However, both strains exhibited only 46.1 % DNA-DNA hybridization with R. vannielii DSM 162(T). Strains JA643(T) and JA755 shared >99 % 16S rRNA gene sequence similarity and were >85 % related on the basis of DNA-DNA hybridization; they are therefore considered to represent a novel species in the genus Rhodomicrobium, for which the name Rhodomicrobium udaipurense sp. nov. is proposed. The type strain is JA643(T) ( = KCTC 15219(T) = NBRC 109057(T)).

Background: Aerobic gammaproteobacteria affiliated to the OM60/NOR5 clade are widespread in saline environments and of ecological importance in several marine ecosystems, especially the euphotic zone of coastal areas. Within this group a close relationship between aerobic anoxygenic photoheterotrophs and non-phototrophic members has been found., Results: Several strains of aerobic red-pigmented bacteria affiliated to the OM60/NOR5 clade were obtained from tidal flat sediment samples at the island of Sylt (North Sea, Germany). Two of the novel isolates, Rap1red and Ivo14(T), were chosen for an analysis in detail. Strain Rap1red shared a 16S rRNA sequence identity of 99% with the type strain of Congregibacter litoralis and was genome-sequenced to reveal the extent of genetic microheterogeneity among closely related strains within this clade. In addition, a draft genome sequence was obtained from the isolate Ivo14(T), which belongs to the environmental important NOR5-1 lineage that contains so far no cultured representative with a comprehensive description. Strain Ivo14(T) was characterized using a polyphasic approach and compared with other red-pigmented members of the OM60/NOR5 clade, including Congregibacter litoralis DSM 17192(T), Haliea rubra DSM 19751(T) and Chromatocurvus halotolerans DSM 23344(T). All analyzed strains contained bacteriochlorophyll a and spirilloxanthin as photosynthetic pigments. Besides a detailed phenotypic characterization including physiological and chemotaxonomic traits, sequence information based on protein-coding genes and a comparison of draft genome data sets were used to identify possible features characteristic for distinct taxa within this clade., Conclusions: Comparative sequence analyses of the pufLM genes of genome-sequenced representatives of the OM60/NOR5 clade indicated that the photosynthetic apparatus of these species was derived from a common ancestor and not acquired by multiple horizontal gene transfer from phylogenetically distant species. An affiliation of the characterized bacteriochlorophyll a-containing strains to different genera was indicated by significant phenotypic differences and pufLM nucleotide sequence identity values below 82%. The revealed high genotypic and phenotypic diversity of closely related strains within this phylogenetic group reflects a rapid evolution and frequent niche separation in the OM60/NOR5 clade, which is possibly driven by the necessities of an adaptation to oligotrophic marine habitats.

Background: Populations of aerobic anoxygenic photoheterotrophic bacteria in marine environments are dominated by members of the Roseobacter lineage within the Alphaproteobacteria and the OM60/NOR5 clade of gammaproteobacteria. A wealth of information exists about the regulation of pigment production and mixotrophic growth in various members of the Roseobacter clade, but a detailed knowledge about aerobic bacteriochlorophyll a-containing gammaproteobacteria is still limited to one strain of the species Congregibacter litoralis., Results: The production of photosynthetic pigments and light-dependent mixotrophic growth was analysed in Luminiphilus syltensis DSM 22749T, Chromatocurvus halotolerans DSM 23344T and Pseudohaliea rubra DSM 19751T, representing three taxonomically diverse strains of bacteriochlorophyll a-containing gammaproteobacteria affiliated to the OM60/NOR5 clade. In these strains the expression of a photosynthetic apparatus depended mainly on the type of carbon source and availability of oxygen. The effect of illumination on pigment expression varied significantly between strains. In contrast to Chromatocurvus halotolerans, pigment production in Luminiphilus syltensis and Pseudohaliea rubra was repressed by light of moderate intensities, probably indicating a higher sensitivity to light-induced oxidative stress. The efficiency of using light for mixotrophic growth did not correlate with the cellular level of photosynthetic pigments, but depended mainly on the type of metabolized substrate with malate being the optimal carbon source in most cases., Conclusions: Oligotrophic growth conditions or carbon limitation were not required for light-dependent mixotrophic growth in members of the OM60/NOR5 clade. The ability of using light as energy source and the fine tuning of photosynthesis gene expression depended mainly on the type of carbon source and oxygen availability, which indicates that the regulation of pigment production is controlled by the cellular redox state. While light has the main impact on the regulation of photosynthetic pigments in photoheterotrophic representatives of the Roseobacter lineage this was not the case in strains of the OM60/NOR5 clade.

Two Gram-reaction-negative, rod-shaped, motile bacteria, designated strains U82 and U95(T), were isolated from the marine alga Ulva australis collected at Sharks Point, Clovelly, a rocky intertidal zone near Sydney, Australia. Both strains were oxidase- and catalase-positive, formed brown- to black-pigmented colonies and required NaCl for growth. Phylogenetic analysis based on nearly complete 16S rRNA gene sequences revealed that these strains belong to the Roseobacter clade within the Alphaproteobacteria. The 16S rRNA genes of both strains were identical across the sequenced 1326 nt, but showed differences in the intergenic spacer region (ITS) between the 16S and the 23S rRNA genes. At the genomic level the DNA G+C contents of strains U82 and U95(T) were identical (52.6 mol%) and they had a DNA-DNA hybridization value of 83.7%, suggesting that these strains belong to the same species. The closest described phylogenetic neighbour to strains U82 and U95(T) was Thalassobius aestuarii DSM 15283(T) with 95.8% 16S rRNA gene sequence similarity. Other close relatives include further species of the genera Thalassobius and Shimia. Strains U82 and U95(T) were negative for bacteriochlorophyll a production, showed antibacterial activity towards other marine bacteria, were resistant to the antibiotics gentamicin and spectinomycin and were unable to hydrolyse starch or gelatin. The major fatty acids (>1%) were 18 : 1ω7c, 16 : 0, 18 : 2, 10 : 0 3-OH, 12 : 0, 20 : 1 2-OH and 18 : 0. The polar lipid pattern indicated the presence of phosphatidylglycerol, phosphatidylcholine, two unidentified aminolipids and four unidentified phospholipids. Both strains produced ubiquinone 10 (Q-10) as the sole respiratory lipoquinone. Based on their phenotypic and phylogenetic characteristics, it is suggested that strains U82 and U95(T) are members of a novel species within a new genus for which the name Epibacterium ulvae gen. nov., sp. nov. is proposed. The type strain of the type species is U95(T) ( = DSM 24752(T) = LMG 26464(T)).

A Gram-stain-negative, aerobic, non-motile and rod-shaped bacterial strain, designated WT-MW11(T), was isolated from wood falls on the coast of Wando, an island of South Korea, and its taxonomic position was investigated by using a polyphasic approach. Strain WT-MW11(T) grew optimally at pH 7.0-8.0, at 25 °C and in the presence of 2.0-3.0 % (w/v) NaCl. Bacteriochlorophyll a was not produced. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain WT-MW11(T) clustered with Pseudorhodobacter ferrugineus IAM 12616(T) and Pseudorhodobacter aquimaris HDW-19(T), with which it exhibited 16S rRNA gene sequence similarity values of 97.9 and 95.5 %, respectively. Strain WT-MW11(T) contained Q-10 as the predominant ubiquinone and C18 : 1ω7c as the major fatty acid. The polar lipid profile of strain WT-MW11(T) was similar to those of P. ferrugineus JCM 20687(T) and P. aquimaris HDW-19(T). The DNA G+C content of strain WT-MW11(T) was 61.6 mol% and its mean DNA-DNA relatedness value with P. ferrugineus JCM 20687(T) was 12.3 %. The phylogenetic and genetic distinctiveness and differential phenotypic properties revealed that strain WT-MW11(T) was distinguishable from the two recognized species of the genus Pseudorhodobacter. On the basis of the data presented, strain WT-MW11(T) is considered to represent a novel species of the genus Pseudorhodobacter, for which the name Pseudorhodobacter wandonensis sp. nov. is proposed. The type strain is WT-MW11(T) ( = KCTC 23672(T) = CCUG 61506(T)). The description of the genus Pseudorhodobacter is emended.

A Gram-staining-negative, pale-pink-pigmented, non-motile, obligately aerobic and rod-shaped bacterium, designated strain W37(T), was isolated from soil and subjected to a taxonomic investigation using a polyphasic approach. The strain grew at 1-30 °C, oxidized thiosulfate and accumulated polyhydroxyalkanoates. Photosynthetic pigments were represented by bacteriochlorophyll a and carotenoids. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain W37(T) was most closely related to members of the genera Roseococcus and Rubritepida (with sequence similarities of <92.8 %) but formed a distinct lineage in the family Acetobacteraceae. The polar lipid profile comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, three unidentified aminolipids and one other unidentified lipid. The predominant cellular fatty acids were C18 : 1ω7c and summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH). The DNA G+C content of strain W37(T) was 68.2 mol%. On the basis of phenotypic characteristics and phylogenetic analysis, strain W37(T) represents a novel species of a new genus in the family Acetobacteraceae, for which the name Humitalea rosea gen. nov., sp. nov. is proposed. The type strain of the type species is W37(T) ( = CIP 110261(T) = LMG 26243(T)).

A Gram-negative, aerobic, non-motile, pink-pigmented and rod-shaped strain, designated ZS3-33(T), was isolated from Antarctic intertidal sandy sediment. The strain grew optimally at 15 °C and with 1.0 % (w/v) NaCl. It reduced nitrate to nitrite and hydrolysed Tween 20. It could not produce bacteriochlorophyll a. The predominant cellular fatty acid was C18 : 1ω7c and the predominant respiratory quinone was Q-10. The major polar lipids were phosphatidylglycerol, phosphatidylcholine, two unidentified aminophospholipids and an unidentified aminolipid. Analyses of 16S rRNA gene sequences revealed that strain ZS3-33(T) belonged to the genus Pseudorhodobacter, showing 97.4 % similarity to the type strain of Pseudorhodobacter ferrugineus and 95.3 % similarity to the type strain of Pseudorhodobacter aquimaris. Levels of gyrB gene sequence similarity between strain ZS3-33(T) and the type strains of P. ferrugineus and P. aquimaris were 87.6 and 81.7 %, respectively. DNA-DNA relatedness between strain ZS3-33(T) and P. ferrugineus DSM 5888(T) was 56.6 %. The genomic DNA G+C content of strain ZS3-33(T) was 57.1 mol%. Based on data from this polyphasic study, strain ZS3-33(T) represents a novel species of the genus Pseudorhodobacter, for which the name Pseudorhodobacter antarcticus sp. nov. is proposed. The type strain is ZS3-33(T) ( = CGMCC 1.10836(T) = KCTC 23700(T)). An emended description of the genus Pseudorhodobacter Uchino et al. 2002 emend. Jung et al. 2012 is also proposed.

A green phototrophic bacterium (strain JA737(T)), which was oval- to rod-shaped, Gram-negative and motile, was isolated from mud of a stream in the Western Ghats of India. Strain JA737(T) contained bacteriochlorophyll a, and the major carotenoid was neurosporene. The major quinone was Q-10 and the polar lipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, an unidentified aminolipid, two unidentified phospholipids and five unidentified lipids. Phylogenetic analysis showed that the strain clustered with members of the genus Rhodobacter belonging to the family Rhodobacteraceae of the class Alphaproteobacteria. Based on 16S rRNA gene sequence analysis, strain JA737(T) had highest sequence similarity with Rhodobacter capsulatus ATCC 11166(T) (98.8 %), Rhodobacter maris JA276(T) (97 %), Rhodobacter aestuarii JA296(T) (96.7 %) and other members of the genus Rhodobacter (<96 %). However, strain JA737(T) showed 22-55 % DNA-DNA relatedness with the above type strains. On the basis of phenotypic, chemotaxonomic and molecular genetic evidence, strain JA737(T) represents a novel species of the genus Rhodobacter, for which the name Rhodobacter viridis sp. nov. is proposed. The type strain is JA737(T) ( = KCTC 15167(T) = MTCC 11105(T) = NBRC 108864(T)).

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.

Two strains (JA266(T) and JA333) of Gram-negative, rod-shaped, phototrophic, purple non-sulfur bacteria were isolated from a freshwater fish pond and an industrial effluent. Both strains were capable of phototrophic and chemotrophic growth. Bacteriochlorophyll a and carotenoids of the spirilloxanthin series were present as photosynthetic pigments. The major fatty acid for both strains was C(18 : 1)ω7c (>65 %), with minor amounts of 11-methyl C(18  : 1)ω7c, C(16 : 0), C(16 : 1)ω7c and C(18 : 0) also present. Both strains have the lamellar type of intracellular photosynthetic membranes. Ubiquinone-10 (Q(10)) and rhodoquinone-10 (RQ(10)) were present as primary quinone components. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine were the major polar lipids, while minor amounts of amino lipids (AL1, AL2) and an unidentified lipid (L1) were common to both strains. The DNA G+C contents of strains JA266(T) and JA333 were 71.3 and 69.9 mol%, respectively. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that both strains clustered with members of the genus Rhodoplanes in the class Alphaproteobacteria. Strains JA266(T) and JA333 had gene sequence similarity of 98.7 and 98.9 % with Rhodoplanes serenus TUT3530(T), 96.4 and 96.5 % with Rhodoplanes elegans AS130(T), respectively, and less than 96 % with other members of the genus Rhodoplanes. 16S rRNA gene sequence similarity between the two strains was 99.3 % and they exhibited high (84.7 %) relatedness based on DNA-DNA hybridization. Furthermore, both strains had less than 65 % DNA-DNA relatedness with the type strain R. serenus TUT3530(T). On the basis of phenotypic and genotypic data, it is proposed that strain JA266(T) be classified as a novel species of the genus Rhodoplanes, with the species name Rhodoplanes piscinae sp. nov. The type strain of the proposed novel species is JA266(T) ( = JCM 14934(T) = KCTC 5627(T)), while strain JA333 ( = NBRC 107574 = KCTC 5962) is an additional strain.

An oval to rod-shaped, Gram-stain-negative, phototrophic bacterium, strain JA738(T), was isolated from a sediment sample collected from a pink pond. Strain JA738(T) was non-motile and had vesicular-type intracellular photosynthetic membranes. Bacteriochlorophyll a and carotenoids of the spheroidene series were present as the major photosynthetic pigments. Strain JA738(T) required thiamine and pantothenate for growth. The major cellular fatty acids were C(18 : 1)ω7c, C(18 : 1)ω5c, C(18 : 0) and C(18 : 1)ω7c11-methyl; minor amounts of C(10 : 0) 3-OH and C(16 : 0) were also present. The major quinone was Q-10 and major polar lipids were phosphatidylglycerol, phosphatidylethanolamine and two unidentified sulfolipids (SL1-2). Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA738(T) clustered with species of the genus Rhodovulum in the class Alphaproteobacteria. Strain JA738(T) was most closely related to Rhodovulum adriaticum DSM 2781(T) (96.4 % 16S rRNA gene sequence similarity) and other members of the genus Rhodovulum (<96.1 %). On the basis of phenotypic and molecular genetic evidence, it is proposed that strain JA738(T) should be classified as a novel species of the genus Rhodovulum for which the name Rhodovulum bhavnagarense sp. nov. is proposed. The type strain is JA738(T) ( = DSM 24766(T) = KCTC 15110(T)).

Objective: Photopigments, including carotenoid and bacteriochlorophyll a, are the most important functional units of photosynthesis in purple bacteria. We developed rapid qualitative and quantitative methods to determine photopigments., Methods: Using Rhodopesudomonas palustris CQV97 as a reference, we used image gray intensity analysis, absorption spectrophotometry, thin layer chromatography (TLC), HPLC and mass spectrometry (MS) for photopigment analysis., Results: The total amount of photopigments increased by 13.5% by using modified acetone-methanol extraction. We developed two types of photopigment fingerprintings by TLC and HPLC, estimated the apparent relative content of each photopigment of fingerprintings, and determined the corresponding relationships between R(f) value of each photopigment on TLC fingerprinting and retention time of each photopigment elution in HPLC fingerprinting. Based on the data from the absorption spectra, MS and related photopigment biosynthetic pathway analysis, we identified 11 photopigments in CQV97 strain. Using this strain as a standard, we analyzed photopigments of the tested samples by TLC or HPLC. It was shown that (1) the relative standard deviation (RSD) of the two methods was less than 5%; (2) the compositions and contents of the theory sample were consistent with that of the standard sample; (3) the photopigment compositions of the real sample was the same as the standard sample, but the photopigment content was different., Conclusion: Both of TLC and HPLC analyses for photopigment determination have good stability and repeatability. The fingerprintings analyses are suitable for rapid determination of photopigments of purple bacteria and have important application in control of regulation mechanism for photopigment synthesis.

A coastal Roseobacter strain of marine aerobic anoxygenic phototrophic bacteria (AAnPB) was isolated and phylogenetically determined. The strain OBYS 0001 was characterized by its physiological and biochemical properties with reference to the Erythrobacter longus type strain NBRC 14126. When grown in batch cultures, the growth curves of the both strains were similar. Cellular bacteriochlorophyll a concentrations of the strains reached the maxima in the stationary growth conditions. In vivo fluorescence excitation/optical density spectra between 470 and 600 nm for OBYS 0001 represented higher values than NBRC 14126. Variable fluorescence measurements revealed that the functional absorption cross section (σ) of the bacterial photosynthetic complexes for OBYS 0001 was significantly higher than that for NBRC 14126 under green excitation. These results suggest that Roseobacter can capture green light more efficiently than Erythrobacter for photosynthesis. The photochemical quantum efficiencies (F (v)/F (m)) of the bacterial photosynthetic complexes for OBYS 0001 were consistently lower than those for NBRC 14126. A relationship between the growth rate and F (v)/F (m) was significant for OBYS 0001, but that was not found for NBRC 14126. These results suggested that F (v)/F (m) for AAnPB could not be used as a proxy of the growth rate which is consistent with their mostly heterotrophic characters.

The reaction centers (RCs) from several species of a purple photosynthetic bacterium, Rhodopseudomonas palustris, were first isolated by ammonium-sulfate fractionation of the isolated core complexes, and were successfully purified by anion-exchange and gel-filtration chromatography as well as sucrose-density gradient centrifugation. The RCs were characterized by spectroscopic and biochemical analyses, indicating that they were sufficiently pure and had conserved their redox activity. The pigment composition of the purified RCs was carefully analyzed by LCMS. Significant accumulation of both bacteriochlorophyll(BChl)-a and bacteriopheophytin(BPhe)-a esterified with various isoprenoid alcohols in the 17-propionate groups was shown in RCs for the first time. Moreover, a drastic decrease in BPhe-a with the most dehydrogenated and rigid geranylgeranyl(GG) ester was observed, indicating that BPhe-a in RC preferably took partially hydrogenated and flexible ester groups, i.e. dihydro-GG and tetrahydro-GG in addition to phytyl. Based on the reported X-ray crystal structures of purple bacterial RCs, the meaning of flexibility of the ester groups in BChl-a and BPhe-a as the cofactors of RCs is proposed., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A Gram-stain-negative, aerobic, motile, ovoid bacterial strain, designated HDW-19(T), was isolated from seawater of the west coast of Korea and subjected to a polyphasic taxonomic study. Strain HDW-19(T) grew optimally at pH 7.0-8.0, at 30 °C and in the presence of 2-3% (w/v) NaCl. Bacteriochlorophyll a was not produced by strain HDW-19(T). Neighbour-joining, maximum-likelihood and maximum-parsimony phylogenetic trees based on 16S rRNA gene sequences showed that strain HDW-19(T) clustered with Pseudorhodobacter ferrugineus IAM 12616(T), with which it shared 96.4% similarity. A neighbour-joining phylogenetic tree based on gyrB gene sequences showed that strain HDW-19(T) also clustered with the type strain of P. ferrugineus, sharing 83.0% similarity. Strain HDW-19(T) contained Q-10 as the predominant ubiquinone and C(18:1)ω7c as the major fatty acid. The major polar lipids were phosphatidylcholine, phosphatidylglycerol, three unidentified aminophospholipids and two unidentified aminolipids. The DNA G+C content of strain HDW-19(T) was 60.9 mol%. Differential phenotypic properties, together with phylogenetic distinctiveness, showed that strain HDW-19(T) can be differentiated from P. ferrugineus. On this basis, strain HDW-19(T) is considered to represent a novel species of the genus Pseudorhodobacter, for which the name Pseudorhodobacter aquimaris sp. nov. is proposed. The type strain is HDW-19(T) (=KCTC 23043(T) =CCUG 58879(T)).

The distribution of aerobic anoxygenic phototrophs (AAPs) was surveyed in various regions of the Mediterranean Sea in spring and summer. These phototrophic bacteria were present within the euphotic layer at all sampled stations. The AAP abundances increased with increasing trophic status ranging from 2.5 × 10(3) cells per ml in oligotrophic Eastern Mediterranean up to 90 × 10(3) cells per ml in the Bay of Villefranche. Aerobic anoxygenic phototrophs made up on average 1-4% of total prokaryotes in low nutrient areas, whereas in coastal and more productive stations these organisms represented 3-11% of total prokaryotes. Diel bacteriochlorophyll a decay measurements showed that AAP community in the Western Mediterranean grew rapidly, at rates from 1.13 to 1.42 day(-1). The lower AAP abundances registered in the most oligotrophic waters suggest that they are relatively poor competitors under nutrient limiting conditions. Instead, AAPs appear to be metabolically active organisms, which thrive better in more eutrophic environments providing the necessary substrates to maintain high growth rates., (© 2011 Society for Applied Microbiology and Blackwell Publishing Ltd.)

A novel Gram-negative, non-motile bacterium, designated strain ZS2-28(T), was isolated from sandy intertidal sediment samples collected from the coastal regions of the Chinese Antarctic Zhongshan Station on the Larsemann Hills, Princess Elizabeth Land, East Antarctica. Strain ZS2-28(T) was obligately heterotrophic, strictly aerobic, psychrotolerant (growth occurred at 0-33 °C) and moderately halophilic (optimal growth in 7-8 % NaCl). A single major peak at 872-874 nm in the infrared absorption spectrum indicated the presence of bacteriochlorophyll a. Poly-β-hydroxybutyrate accumulation and slime production were also detected. The predominant cellular fatty acid was C₁₈:₁ω7c, with C₁₀:₀ 3-OH, C₁₆:₀, C₁₇:₀ cyclo, C₁₉:₀ω8c cyclo and summed feature 3 (C₁₆:₁ω7c and/or iso-C₁₅:₀ 2-OH) present in smaller amounts. The respiratory quinone was Q-10. The main polar lipids were phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine and an unidentified aminolipid. The G+C content of the genomic DNA was 63.3 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain ZS2-28(T) formed a distinct evolutionary lineage within the clade containing members of the genera Roseibaca, Roseinatronobacter and Rhodobaca of the class Alphaproteobacteria. On the basis of its phylogenetic position, as well as its phenotypic and chemotaxonomic characteristics, strain ZS2-28(T) represents a novel species of a novel genus, for which the name Roseicitreum antarcticum gen. nov., sp. nov. is proposed. The type strain is ZS2-28(T) ( = CGMCC 1.8894(T)  = LMG 24863(T)).

A strain EG19(T) of aerobic bacteria able to form pleomorphic cells was isolated from a brine spring runoff stream in the west central region of the province of Manitoba, Canada. The pale pinkish purple strain contained bacteriochlorophyll a incorporated into light-harvesting I and reaction center complexes. Its inability to grow under anaerobic illuminated conditions prompted designation as a member of the functional group known as aerobic anoxygenic phototrophic bacteria. Phylogenetic analysis of the 16S rRNA gene sequence revealed that it belonged to the Gammaproteobacteria, forming a distinct branch of phototrophs distantly related to most described aerobic anoxygenic phototrophs, quite marginally related (95.6%) both to the only other described gammaproteobacterial aerobic phototroph, Congregibacter litoralis, and also to nonphototrophs in the genus Haliea (95.1-96.1%). Physiological tests demonstrated tolerance profiles to salinity (0-18% NaCl), pH (7-12), and temperature (7-40°C) consistent with survival in a shallow hypersaline stream on the exposed, vegetation-depleted salt playa of its native East German Creek. Phylogenetic data and phenotypic properties such as pigment composition, morphology, and physiology support the proposal of the novel genus and species Chromocurvus halotolerans gen. nov., sp. nov., with EG19(T) (=DSM 23344(T), =VKM B-2659(T)) as the type strain.

Two strains (JA480(T) and JA481) of phototrophic alphaproteobacteria were isolated from sediment samples collected from brackish water near Nagapattinam, India. They were Gram-negative, vibrioid cells containing bacteriochlorophyll a and rhodopin as major photosynthetic pigments. Most cells of both strains were non-flagellated; 1 % of cells showed two monopolar flagella. Cells showed positive phototaxis. Both strains showed chimeric intracellular photosynthetic membranes, where both lamellar stacks and vesicles were present together in a single cell. The major fatty acids were C(18 : 1)ω7c and C(16 : 0) in both strains. The genomic G+C content was 67.2-68.8 mol% and the two strains were closely related (mean DNA-DNA hybridization >85 %). 16S rRNA gene sequence comparisons indicated that the isolates represent members of the Rhodospirillaceae within the class Alphaproteobacteria. According to the sequence comparison data, strain JA480(T) is positioned distinctly outside the group formed by the phototrophic genera Rhodospirillum, Rhodocista, Phaeospirillum, Rhodovibrio, Rhodospira and Roseospira, with only 80-92 % 16S rRNA gene sequence similarity. Distinct morphological, physiological and genotypic differences from previously described taxa support the classification of this isolate as a representative of a novel species in a new genus, for which the name Phaeovibrio sulfidiphilus gen. nov., sp. nov. is proposed. The type strain of Phaeovibrio sulfidiphilus is JA480(T) ( = KCTC 5825(T)  = NBRC 106163(T)  = DSM 23193(T)).

Anaerobic anoxygenic phototrophic bacteria can be found in the suboxic waters of shallow stratified coastal systems, and may play important roles in the total primary production of subtropical stratified coastal lagoons. We investigated the spatiotemporal variability of light CO(2) fixation and net oxygen production in the stratified Conceição Lagoon (Brazil) in summer and fall of 2007, as well as the contribution of bacteriochlorophyll a (BChl a)-containing bacteria to photosynthetically driven electron transfer. Both chlorophyll a (Chl a) and BChl a varied in space, while only BChl a varied in time (three-fold increase from summer to fall). In summer, net oxygen production and light CO(2) fixation were correlated, with both having higher rates with higher Chl a concentrations in the enclosed region of the lagoon. In fall, CO(2) fixation was decoupled from oxygen production. Denaturing gradient gel electrophoresis revealed that bacterial communities of oxic site 12 and suboxic site 33 formed one cluster, different from other oxic samples within the lagoon. In addition, BChl a/Chl a ratios at these sites were high, 40% and 45%, respectively. Light acted as the main factor controlling the BChl a concentration and CO(2) fixation rates. High turbidity within the enclosed area of the lagoon explained high BChl a and decoupling between CO(2) fixation and oxygen production in oxygenated waters. Contribution of purple sulfur bacteria to total bacterial density in suboxic waters was 1.2%, and their biomass contributed to a much higher percentage (12.2%) due to their large biovolume. Our results indicate a significant contribution of anaerobic anoxygenic bacteria to the primary production of the "dead zone" of Conceição Lagoon.

Two strains of oval-rod shaped, Gram-negative, phototrophic, purple non-sulfur bacteria designated JA580(T) and JA595 were isolated from a sediment sample collected from a brown pond. Strain JA580(T) was designated as the type strain, while strain JA595 as an additional strain has similar characteristics to the type strain. Strain JA580(T) was non-motile and grew photoheterotrophically with a number of organic compounds serving as carbon source/electron donor. Intracellular photosynthetic membranes were of the vesicular type. Bacteriochlorophyll a and carotenoids of the spheroidene series were present as the major photosynthetic pigments. Strain JA580(T) requires yeast extract for growth. Strain JA580(T) has an obligate requirement for sulfide or thiosulfate for growth. C(18:1)ω7c, C(18:0), C(18:1)ω9c were the predominant components of cellular fatty acids. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA580(T) clustered with species of the genus Rhodovulum of the family Rhodobacteraceae and is most closely related to the type strains of Rhodovulum adriaticum, Rhodovulum iodosum (96.5%), Rhodovulum robiginosum (96%), Rhodovulum imhoffii (95.6%) and other members of the genus Rhodovulum (<95%). On the basis of phenotypic and molecular genetic evidence, it is proposed that strain JA580(T) should be classified as a novel species of the genus Rhodovulum of the family Rhodobacteraceae, with the species name Rhodovulum phaeolacus sp. nov. The type strain of the species is JA580(T) (=NBRC 107612(T) =KCTC 5963(T)).

Two strains (JC17(T) and JC19a) of orange pigmented bacteria were isolated from an estuarine sample. Cells of both the strains were Gram-negative coccobacilli, non-motile, non-spore forming and strictly aerobic. Chemo-organoheterotrophy was the growth mode for both strains and was possible on a wide range of organic compounds. Strains were non-hemolytic and contained low levels of BChl-a and carotenoids. The fatty acids (>1.0%) comprised C(18:1)omega7c, C(16:1)omega7c/iso-C(15:0)2OH, C(16:0), C(16:0) 3-OH, C(18:1)2OH, C(16:1)omega5c, and C(19:0) cycloomega8c. The genomic DNA G+C content of strain JC17(T) was 66.2mol%. A phylogenetic tree based on 16S rRNA gene sequence analysis showed that strains JC17(T) and JC19a had the highest similarity to members of the genus Roseomonas and were closely related to Roseomonas cervicalis CIP104027(T) (96.4%) and Roseomonas ludipueritiae CIP107418(T) (96.3%) of the family Acetobacteraceae within the class Alphaproteobacteria. Strains JC17(T) and JC19a shared 100% 16S rRNA gene sequence similarity, were phenotypically (morphological, physiological, biochemical characters) identical and had closely related genomes (85% DDH). Based on polyphasic taxonomic data, strain JC17(T) is classified as a novel species of the genus Roseomonas for which the name Roseomonas aestuarii sp. nov. is proposed. The type strain is JC17(T) (=CCUG 57456(T) =KCTC 22692(T) =NBRC105654(T)).

A Gram-negative, rod-shaped, purple non-sulfur bacterial strain, designated JA415T, was isolated from the mud of a pokkali rice field located on Vypeen Island, Ernakulam, Kerala, India. Strain JA415T was motile by means of a single polar flagellum. Photo- and chemo-organoheterotrophic growth was observed using organic compounds as carbon sources and electron donors. Photo- and chemolithoautotrophic growth using thiosulfate as electron donor did not occur. Fermentative growth could not be demonstrated. Intracellular photosynthetic membranes were lamellar stacks parallel to the cytoplasmic membrane. Bacteriochlorophyll a and carotenoids of the spirilloxanthin series were present as photosynthetic pigments. Niacin, pantothenate and p-aminobenzoate were required as growth factors. C18:1omega7c was the predominant cellular fatty acid component. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain JA415T clustered with members of the genus Rhodoplanes in the class Alphaproteobacteria. On the basis of phenotypic and molecular genetic evidence, it is proposed that strain JA415T be classified as a representative of a novel species of the genus Rhodoplanes, family Hyphomicrobiaceae, with the name Rhodoplanes pokkaliisoli sp. nov. The type strain is JA415T (=KCTC 5711T=NBRC 104972T).

A Gram-negative, aerobic, neutrophilic, coccoid bacterium, strain E4A9T, was isolated from a deep-sea sediment sample collected from the East Pacific polymetallic nodule region. 16S rRNA gene sequence analysis showed that the isolate was related to the type strain of Altererythrobacter epoxidivorans (96.0% sequence similarity). Lower 16S rRNA gene sequence similarities were observed with other members of the genera Altererythrobacter (94.7%), Erythrobacter (94.0-95.4%), Erythromicrobium (94.8%) and Porphyrobacter (94.6-95.1%) of the family Erythrobacteraceae. Phylogenetic analysis including all described species of the family Erythrobacteraceae and several members of the family Sphingomonadaceae revealed that the isolate formed a distinct phylogenetic lineage with the family Erythrobacteraceae. Chemotaxonomic analysis revealed ubiquinone-10 as the predominant respiratory quinone, anteiso-C15:0, iso-C14:0 and iso-C15:0 as major fatty acids, and phosphatidylglycerol as the major polar lipid. The DNA G+C content was 71.5 mol%. The isolate contained carotenoids, but no bacteriochlorophyll a. On the basis of phenotypic and genotypic data presented in this study, strain E4A9T represents a novel species in a new genus in the family Erythrobacteraceae for which the name Croceicoccus marinus gen. nov., sp. nov. is proposed; the type strain is E4A9T (=CGMCC 1.6776T=JCM 14846T).

A spherical-shaped, phototrophic, purple sulfur bacterium was isolated in pure culture from anoxic sediment in a marine aquaculture pond near Bheemli (India). Strain JA142T is Gram-negative and non-motile. It has a requirement for NaCl (optimum of 2% and maximum of 6% w/v NaCl). Intracellular photosynthetic membranes are of the vesicular type. In vivo absorption spectra indicate the presence of bacteriochlorophyll a and carotenoids of the okenone series as photosynthetic pigments. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA142T is related to halophilic purple sulfur bacteria of the genera Thiohalocapsa and Halochromatium, with the highest sequence similarity to Thiohalocapsa halophila DSM 6210T (97.5%). Morphological and physiological characteristics differentiate strain JA142T from other species of the genera Halochromatium and Thiohalocapsa. Strain JA142T is sufficiently different from Thiohalocapsa halophila based on 16S rRNA gene sequence analysis and morphological and physiological characteristics to allow the proposal of a novel species, Thiohalocapsa marina sp. nov., with the type strain JA142T (=JCM 14780T=DSM 19078T).

A Gram-negative, aerobic rod was isolated from the hypersaline, heliothermal and meromictic Ekho Lake (East Antarctica) at a depth of 6 m. The novel strain (designated EL-50T) was oxidase-positive and weakly catalase-positive and metabolized a variety of carboxylic acids, alcohols, sugars and lipids. Cells of strain EL-50T had an absolute requirement for artificial seawater or NaCl. Optimum growth occurred at 16 degrees C and at pH values ranging from 7.0 to 9.5. A large in vivo absorption band at 865-866 nm indicated the production of bacteriochlorophyll (bchl) a. The predominant cellular fatty acid of strain EL-50T was 18:1omega7c, with 3-OH 14:1, 16:1omega9c, 16:0 and 18:1omega9c present in lower amounts. Fatty acids 16:0 and 18:1omega9c were probably amide-linked. The main polar lipids were diphosphatidylglycerol, phospatidylethanolamine, phosphatidylglycerol and phosphatidylcholine. Ubiquinone 10 was produced. The cell-wall diamino acid was meso-diaminopimelic acid. The DNA G+C content of strain EL-50T was 61 mol%. 16S rRNA gene sequence comparisons indicated that the novel isolate was phylogenetically most closely related to alkaliphilic Rhodobaca and Roseinatronobacter species (approximately 96% 16S rRNA gene similarity). The organism had no particular relationship to any other cultivated members within the Alphaproteobacteria. The distinct morphological, physiological and genotypic differences from the previously described taxa studied supported the description of a new genus and novel species, for which the name Roseibaca ekhonensis gen. nov., sp. nov. is proposed. The type strain is EL-50T (=DSM 11469T=CECT 7235T).

During studies of moderately halophilic strains of Ectothiorhodospira from steppe soda lakes, we found a novel group of bacteria related to Ectothiorhodospira haloalkaliphila with salt optima at 50-80 g NaCl l(-1). Phylogenetic analysis using 16S rRNA gene sequences of strains from soda lakes in Mongolia, Egypt and Siberia revealed separation of the group of new isolates from other Ectothiorhodospira species, including the closely related Ect. haloalkaliphila. DNA-DNA hybridization studies demonstrated that the new isolates form a homogeneous group at the species level, but at the same time are distinct from related species such as Ect. haloalkaliphila, Ect. vacuolata, Ect. shaposhnikovii and Ect. marina. The new isolates are considered to be strains of a novel species, for which the name Ectothiorhodospira variabilis sp. nov. is proposed, with the type strain WN22(T) (=VKM B-2479(T) =DSM 21381(T)). Photosynthetic pigments of the novel species are bacteriochlorophyll a and carotenoids of the spirilloxanthin series with spirilloxanthin and derivatives thereof, together with small amounts of lycopene and rhodopin. Gas vesicles are formed by most of the strains, particularly in media containing yeast extract (0.5 g l(-1)) and acetate (0.5-2.0 g l(-1)). Sequence analysis of nifH (nitrogenase) and cbbL (RuBisCO) confirmed the assignment of the strains to the genus Ectothiorhodospira and in particular the close relationship to Ect. haloalkaliphila. The novel species Ect. variabilis is found in soda lakes separated by great geographical distances and is an alkaliphilic and halophilic bacterium that tolerates salt concentrations up to 150-200 g NaCl l(-1).

A novel strain, SHET, of aerobic bacteriochlorophyll a-containing bacteria was isolated from the surface layer of bottom sediments from the soda lake Shuluutai-Ekhe-Torom (Chita oblast, Eastern Siberia, Russia). The lake water has a total mineralization of 3.0 g/l and a pH of 9.2. The cells of strain SHET are cocci or short rods, which reproduce by uniform division. The cells are motile by means of flagella. The cell wall structure is of the gram-negative type. Sparse intracytoplasmic membrane vesicles are located close to the cell wall. The new isolate is an obligate aerobe and facultative alkaliphile which grows in a pH range of 7.5-9.5 (with an optimum at pH 8.5-9.0). The best growth of strain SHET occurred at 2.0 g/l NaCl and 23-28 degrees C. Photosynthetic pigments are represented by bacteriochlorophyll a, with the maximum absorption at 865 nm in the in vivo spectrum, and carotenoids (spirilloxanthin derivatives). Analysis of the 16S rRNA gene sequences demonstrated that strain SHET is closely related to Roseococcus thiosulfatophilus of the alpha-1 subclass of Proteobacteria (98.6 % similarity). The DNA G + C base content is 69.1 mol %. Unlike Rsc. thiosulfatophilus, strain SHET grows well on sugars and glycerol and is not capable of utilizing thiosulfate as an energy source. The new isolate is a facultative alkaliphile and reduces nitrates to nitrites. On the basis of its phenotypic and genetic characteristics, strain SHET was described as a new species of the genus Roseococcus, Rsc. suduntuyensis sp. nov.

A Gram-negative, strictly aerobic, diplococcoid bacterium (strain D2-3(T)) was isolated from the biofilter of a recirculating marine aquaculture system. Phylogenetic analysis of the 16S rRNA gene sequence of D2-3(T) indicated that the new organism occupied a novel lineage within the alpha-1 subclass of Proteobacteria and was related to the genera Rhodothalassium, Azospirillum, Craurococcus, Acidiphilium, and Tistrella. The highest sequence similarity (90.8%) of the 16S rRNA gene sequence of D2-3(T) was to that of Candidatus "Alysiosphaera europaea". D2-3(T) was mesophilic, heterotrophic, required sea salt, and had a pH optimum of 8.0. Growth in the presence of light resulted in the formation of pink colonies, a 25% increased cell yield, and a slightly increased growth rate. D2-3(T) contained carotenoids and low amounts of bacteriochlorophyll a. Membranes of D2-3(T) contained b-type cytochromes. The G+C content of the DNA was 60.3+/-0.1mol%. Phylogenetic, morphological, physiological, and biochemical analyses demonstrated that D2-3(T) represented a new aerobic phototrophic genus, for which the name Geminicoccus roseus gen. nov., sp. nov. is proposed for the type species (D2-3(T)=DSM 18922(T)=ATCC BAA-1445(T)).

A novel marine bacterium, strain JCS350(T), was isolated from marine sediment samples collected from a cold-seep area. The 16S rRNA gene sequence of the isolate showed high similarity to that of Erythrobacter luteolus SW-109(T) (95.9 % sequence similarity). Lower 16S rRNA gene sequence similarities were shown to other members of the genus Erythrobacter (94.6-95.4 %) and members of the genus Porphyrobacter (94.5-95.2 %). Phylogenetic analysis with all members of the family Erythrobacteraceae and several members of the family Sphingomonadaceae revealed that the isolate formed a phyletic line with [Erythrobacter] luteolus that was distinct from other members of the family Erythrobacteraceae. The dominant fatty acids of strain JCS350(T) were 18 : 1omega7c, 16 : 1omega7c and cyclopropane 17 : 0. The major respiratory quinone was ubiquinone 10. The DNA G+C content was 54.5 mol%. The isolate did not contain bacteriochlorophyll a. Optimal growth required the presence of 2 % (w/v) NaCl with either 0.18 % CaCl(2) or 0.59 % MgCl(2), at pH 6.5 and at 35 degrees C. On the basis of the evidence of this polyphasic taxonomic study, strain JCS350(T) should be classified in a novel genus and species in the family Erythrobacteraceae, for which the name Altererythrobacter epoxidivorans gen. nov., sp. nov. is proposed. The misclassified species [Erythrobacter] luteolus is transferred to the new genus as Altererythrobacter luteolus comb. nov. The type strain of Altererythrobacter epoxidivorans is JCS350(T) (=KCCM 42314(T) =JCM 13815(T)) and the type strain of Altererythrobacter luteolus is SW-109(T) (=KCTC 12311(T) =JCM 12599(T)).

A rod-shaped, marine, phototrophic, purple sulfur bacterium containing gas vesicles was isolated from a marine solar saltern at Kakinada, India. Cells of strain JA134(T) are Gram-negative, non-motile rods, with vesicular intracytoplasmic membranes, and the strain has an absolute requirement for NaCl for growth. Bacteriochlorophyll a and the carotenoid okenone are present as photosynthetic pigments. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA134(T) clusters with members of the genus Halochromatium, but is distinctly separated from the species reported so far. The morphological and physiological differences of strain JA134(T) from other Halochromatium species support the description of strain JA134(T) (=ATCC BAA-1363(T) =DSM 18859(T) =JCM 14151(T)) as the type strain of a novel species, Halochromatium roseum sp. nov.

A rod-shaped, phototrophic, purple non-sulfur bacterium was isolated in pure culture from seawater collected from the seashore of Visakhapatnam, on the east coast of India, in a medium that contained 2 % NaCl (w/v). Strain JA123(T) was Gram-negative and non-motile and had a requirement for NaCl. Photo-organoheterotrophic and chemo-organoheterotrophic growth occurred with organic compounds as carbon sources and electron donors. Photolithoautotrophic, chemolithoautotrophic and fermentative growth could not be demonstrated. Strain JA123(T) contained vesicular intracellular photosynthetic membrane structures. Bacteriochlorophyll a and probably carotenoids of the spheroidene series were present as photosynthetic pigments. Biotin was required for growth. Phylogenetic analysis on the basis of 16S rRNA gene sequences showed that strain JA123(T) clustered with species of the genus Rhodobacter. Based on 16S rRNA gene sequence analysis and morphological and physiological characteristics, strain JA123(T) is sufficiently different from other Rhodobacter species to propose a novel species, Rhodobacter vinaykumarii sp. nov., to accommodate this strain; the type strain is JA123(T) (=DSM 18714(T) =JCM 14544(T) =CCUG 54311(T)).

A novel budding purple non-sulfur bacterium (strain AR2102(T)) was isolated in pure culture from a microbial mat that had developed in brackish-water ponds on the coral rim of the atoll of Rangiroa (Tuamotu Islands, French Polynesia). Single cells of this strain were rod-shaped and motile by means of polar flagella and divided by budding. Their intracellular photosynthetic membranes were of the lamellar type. Bacteriochlorophyll a and carotenoids of the normal spirilloxanthin series, with spirilloxanthin as the main carotenoid, were present as photosynthetic pigments. Bacteriochlorophyll a absorption in the infrared portion of the light spectrum exhibited an unusual in vivo absorption peak at 909 nm. The strain grew optimally under photoheterotrophic conditions, but could grow photolithotrophically on thiosulfate or chemo-organotrophically under micro-oxic conditions. Optimal growth occurred in the presence of 1-2 % NaCl. Comparative sequence analysis of the 16S rRNA gene placed strain AR2102(T) within the class Alphaproteobacteria, in a cluster with Rhodobium species. Representatives of this cluster form a closely related group of slightly to moderately halotolerant to halophilic, rod-shaped, purple non-sulfur bacteria that divide by budding. The new isolate exhibited some differences in physiology (no utilization of alcohols or carbohydrates) and genetic characteristics (low relatedness in DNA-DNA hybridization) as well as in its relation to light (differences in absorption wavelengths) from previously described Rhodobium species. Consequently, we propose that strain AR2102(T) (=DSM 17143(T)=ATCC BAA-1145(T)) should be considered as the type strain of a novel species within the genus Rhodobium, Rhodobium pfennigii sp. nov.

The pigment composition of "Candidatus Chlorothrix halophila," a filamentous anoxygenic phototrophic bacterium found in Baja California Sur, Mexico, was determined. Previous work showed that bacteriochlorophyll c (BChl c) was the major pigment in "Ca. Chlorothrix halophila," but it was not clear if this bacterium also contains BChl a (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181:17-25, 2004). Here we show that in addition to BChl c, a small amount of a pigment that is spectrally indistinguishable from BChl a is present in cell extracts of "Ca. Chlorothrix halophila." Nevertheless, the BChl a-like pigment from "Ca. Chlorothrix halophila" has a different molecular weight and a different high-performance liquid chromatography elution time than BChl a from other photosynthetic bacteria. Based on mass spectrometry and other spectroscopic analysis, we determined that the BChl a-like pigment in "Ca. Chlorothrix halophila" contains a tetrahydrogeranylgeraniol tail rather than the phytol tail that is present in BChl a. The carotenoids and major BChl c homologs in "Ca. Chlorothrix halophila" were also identified. BChls c were found to be farnesol esterified and geranylgeraniol esterified.

A pink-pigmented, phototrophic, purple nonsulfur bacterium, strain JA173(T), was isolated in pure culture from a saltern in Gokarna, India, in a medium containing 2 % (w/v) NaCl. Strain JA173(T) was a non-motile Gram-negative rod that multiplied by budding. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain JA173(T) clusters with the class Alphaproteobacteria; highest sequence similarity (98 %) was to the type strain of Rhodobium orientis and 94 % similarity was observed to the 16S rRNA gene sequence of the type strain of Rhodobium marinum. However, DNA-DNA hybridization with R. orientis DSM 11290(T) revealed a relatedness value of only 35.1 % with strain JA173(T). Strain JA173(T) contained lamellar internal membranes, bacteriochlorophyll a and carotenoids of the spirilloxanthin series. Strain JA173(T) had an obligate requirement for NaCl (optimum growth at 2-6 %, w/v) and grew photoheterotrophically with a number of organic compounds as carbon source or electron donor. Photoautotrophic, chemoautotrophic and fermentative growth could not be demonstrated. Yeast extract was required for growth. Based on 16S rRNA gene sequence analysis, DNA-DNA hybridization data and morphological and physiological characteristics, strain JA173(T) is sufficiently different from other species of the genus Rhodobium to be recognized as a representative of a novel species, Rhodobium gokarnense sp. nov. The type strain is JA173(T) (=ATCC BAA-1215(T)=DSM 17935(T)=JCM 13532(T)).

In the final stage of bacteriochlorophyll (BChl) biosynthesis, the presence of BChl-a molecules possessing dihydrogeranylgeranyl and tetrahydrogeranylgeranyl groups at the 17-propionate has been reported. However, the molecular structures of such BChls-a have not yet been determined in terms of the positions of CC double bonds in the 17(2)-ester. In this study, we isolated significant amounts of such pure BChls-a from Rhodopseudomonas palustris and determined their structures by both mass spectrometry and (1)H and (13)C NMR spectroscopy. The determined structures enable us to discuss a stepwise reduction from a geranylgeranyl to phytyl substituent.

A symbiotic green sulfur bacterium, strain CaD, was isolated from an enrichment culture of the phototrophic consortium "Chlorochromatium aggregatum". The capability of the epibiont to grow in pure culture indicates that it is not obligately symbiotic. Cells are Gram-negative, nonmotile, rod-shaped and contain chlorosomes. Strain CaD is obligately anaerobic and photolithoautotrophic, using sulfide as electron donor. Acetate and peptone are photoassimilated in the presence of sulfide and hydrogencarbonate. Photosynthetic pigments contain bacteriochlorophylls a and c, and gamma-carotene and OH-gamma-carotene glucoside laurate as the dominant carotenoids. In cells from pure cultures, chlorosomes are equally distributed along the inner face of the cytoplasmic membrane. In contrast, the distribution of the chlorosomes in symbiotic epibiont cells is uneven, with chlorosomes being entirely absent at the site of attachment to the central bacterium. The symbiotic epibiont cells display a conspicuous additional layered structure at the attachment site. The G + C content of genomic DNA of strain CaD is 46.7 mol%. On the basis of 16S rRNA sequence comparison, the strain is distantly related to Chlorobium species within the green sulfur bacteria phylum (

We determined the concentrations of bacteriochlorophylls (BChl) in the light-harvesting antennae of Oscillochloris trichoides (of the family Oscillochloridaceae belonging to green filamentous mesophilic bacteria) cultivated either with gabaculine, an inhibitor of the C-5 pathway of BChl biosynthesis in a number of bacteria, or at various illumination intensities. We determined the BChl c: BChl a molar ratios in intact cells, in chlorosome-membrane complexes, and in isolated chlorosomes. We revealed that BChl c synthesis in Osc. trichoides was more gabaculine-sensitive than BChl a synthesis. Accordingly, an increase in gabaculine concentrations in the medium resulted in a decrease in the BChl c: BChl a ratio in the tested samples. We suggest that BChl synthesis in Osc. trichoides proceeds via the C-5 pathway, similar to representatives of other families of green bacteria (Chlorobium limicola and Chloroflexus aurantiacus). We demonstrated that the BChl c: BChl a ratio in the chlorosomes varied from 55 : 1 to 110 : 1, depending on light intensity. This ratio is, therefore, closer to that of Chlorobiaceae, and it significantly exceeds the BChl c: BChl a ratio in Chloroflexaceae.

An aerobic, Gram-negative bacterial isolate, strain DX5-10T, was isolated from coastal sediment of the East China Sea. The taxonomy of strain DX5-10T was studied by phenotypic and phylogenetic methods. Strain DX5-10T was motile, formed faint-yellowish colonies and was positive for catalase reaction and weakly positive for oxidase reaction. The nearly complete 16S rRNA gene of strain DX5-10T was obtained and sequence analysis indicated that strain DX5-10T represented an independent lineage within the Roseobacter clade of Alphaproteobacteria. Strain DX5-10T was phylogenetically related to members of the genera Roseobacter, Loktanella, Roseisalinus, Silicibacter, Antarctobacter, Sulfitobacter, Salipiger, Ruegeria and Roseivivax, and the sequence identities among them were less than 95.0%. The predominant respiratory ubiquinone of strain DX5-10T was Q-10 and the DNA G + C content of strain DX5-10T was 63.3 mol%. Therefore, strain DX5-10T represents a novel species of a novel genus, for which the name Yangia pacifica gen. nov., sp. nov. is proposed, with the type strain DX5-10T (= CGMCC 1.3455T = JCM 12573T).

Strain B33(T) is a moderately halophilic, exopolysaccharide-producing, Gram-negative, non-motile rod isolated from a hypersaline soil bordering a saline saltern on the Mediterranean seaboard in Murcia (Spain). The bacterium is chemoheterotrophic and strictly aerobic. It contains a pink pigment but does not synthesize bacteriochlorophyll a. It requires 0.66 M Na+, 0.1 M Mg2+ and 0.1 M K+ for optimum growth. It does not produce acid from carbohydrates. It cannot grow with carbohydrates, organic acids, sugars, alcohols or amino acids as sole sources of carbon and energy. Its major fatty-acids are 18 : 1omega7c (68.9 %) and 19 : 0 cyclo omega8c (12.8 %). The sole respiratory lipoquinone found in strain B33T is ubiquinone-10. The DNA G+C content is 64.2 mol%. 16S rRNA gene sequence comparisons show that the isolate is a member of the Roseobacter clade within the class 'Alphaproteobacteria'. The similarity values with Roseivivax halodurans and Roseivivax halotolerans are 88.2 and 88.0 % respectively and 92.2 % with Salipiger mucosus. DNA-DNA hybridization values with these species are <30 %. In the light of the polyphasic evidence gathered in this study it is proposed that the isolate be classified as a novel genus and species with the name Palleronia marisminoris gen. nov., sp. nov. The proposed type strain is strain B33T (=CECT 7066T=LMG 22959T).

Among a group of marine isolates that were found to be positive for genes of the bacterial photosynthetic reaction centre, a strain was selected for characterization that was phylogenetically close to the genus Roseovarius. The strain, designated DFL-24T, originated from a culture of Alexandrium ostenfeldii (dinoflagellate) and contained small amounts of bacteriochlorophyll a, corresponding to about 1 % of the amount found in intensely pigmented aerobic phototrophs such as Roseobacter litoralis. Cells were rods of 0.5-0.7x1.3-3.0 microm often with uneven ends, suggesting a budding mode of division. True motility was not observed. Electron micrographs of ultrathin sections revealed a Gram-negative cell-wall structure. Cultures did not grow without addition of sea salts and tolerated up to 10 % (w/v) sea-water salts. Acetate, butyrate, tricarboxylic acid cycle intermediates, glutamate and glycerol were used as growth substrates, but not glucose or fructose. Biotin, thiamine and nicotinic acid were required as growth factors. The DNA G+C content was 63 mol%. 16S rRNA gene sequence analysis placed the strain within the Roseobacter lineage of the 'Alphaproteobacteria'. Its closest phylogenetic neighbour was Roseovarius tolerans showing 96.4 % 16S rRNA gene sequence similarity. Based also on its physiological and biochemical characteristics, the strain is considered to represent a novel species of the genus Roseovarius, Roseovarius mucosus sp. nov. Strain DFL-24T (=DSM 17069T=NCIMB 14077T) is the type strain. The 16S rRNA gene sequence of DFL-24T was found to have a similarity of 99.7 % with an unidentified strain, 253-13 (=DSM 17070), which was likewise characterized and shown to constitute another strain of the species.

A Gram-negative, non-spore-forming, yellow-pigmented, slightly halophilic bacterial strain, SW-109(T), was isolated from a tidal flat of the Yellow Sea in Korea, and subjected to a polyphasic taxonomic study. This isolate did not produce bacteriochlorophyll a and contained ubiquinone-10 as the predominant respiratory lipoquinone and C(18 : 1)omega7c as the major fatty acid. The DNA G + C content was 60.3 mol%. Phylogenetic analyses based on 16S rRNA gene sequences showed that strain SW-109(T) is phylogenetically affiliated to the genus Erythrobacter of the family Sphingomonadaceae. Strain SW-109(T) exhibited levels of 16S rRNA gene sequence similarity to the type strains of Erythrobacter species of 94.0-96.3 %, making it possible to categorize strain SW-109(T) as a species that is separate from previously recognized Erythrobacter species. On the basis of its phenotypic properties and phylogenetic distinctiveness, SW-109(T) (= KCTC 12311(T) = JCM 12599(T)) was classified as the type strain of a novel Erythrobacter species, for which the name Erythrobacter luteolus sp. nov. is proposed.