Novel aerobic anoxygenic phototrophic bacterium Jannaschia pagri sp. nov., isolated from seawater around a fish farm.

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_62T (= 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 12N15T (94.6% identity), which have been reported to produce BChl a. The genomic characteristic of strain AI_62T 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_62T (= DSM 115720 T = NBRC 115938 T).

Three-dimensional structure of the Rhodobacter sphaeroides RC-LH1-PufX complex: dimerization and quinone channels promoted by PufX.

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 αß subunits, with two BChls sandwiched between each αß pair of transmembrane helices. The N- and C-terminal extrinsic domains of PufX promote dimerization by interacting with the corresponding domains of an LH1 ß polypeptide from the other half of the RC-LH1-PufX complex. Close contacts between PufX, an LH1 αß 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.

Isolation and pigment composition of the reaction centers from purple photosynthetic bacterium Rhodopseudomonas palustris species.

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.

Cultivation of Aquincola tertiaricarbonis L108 on the fuel oxygenate intermediate tert-butyl alcohol induces aerobic anoxygenic photosynthesis at extremely low feeding rates.

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.

Mixotrophic growth of bacteriochlorophyll a-containing members of the OM60/NOR5 clade of marine gammaproteobacteria is carbon-starvation independent and correlates with the type of carbon source and oxygen availability.

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.

Taxonomy and evolution of bacteriochlorophyll a-containing members of the OM60/NOR5 clade of marine gammaproteobacteria: description of Luminiphilus syltensis gen. nov., sp. nov., reclassification of Haliea rubra as Pseudohaliea rubra gen. nov., comb. nov., and emendation of Chromatocurvus halotolerans.

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.

Pseudorhodobacter wandonensis sp. nov., isolated from wood falls, and emended description of the genus Pseudorhodobacter.

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.

Humitalea rosea gen. nov., sp. nov., an aerobic bacteriochlorophyll-containing bacterium of the family Acetobacteraceae isolated from soil.

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)).

Rhodobacter viridis sp. nov., a phototrophic bacterium isolated from mud of a stream.

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)).

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.

Epibacterium ulvae gen. nov., sp. nov., epibiotic bacteria isolated from the surface of a marine alga.

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)).

Rhodomicrobium udaipurense sp. nov., a psychrotolerant, phototrophic alphaproteobacterium isolated from a freshwater stream.

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)).

Pseudorhodobacter antarcticus sp. nov., isolated from Antarctic intertidal sandy sediment, and emended description of the genus Pseudorhodobacter Uchino et al. 2002 emend. Jung et al. 2012.

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.

Rhodospirillum oryzae sp. nov., a phototrophic bacterium isolated from rhizosphere soil of paddy.

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)).

Photosynthetic characteristics of marine aerobic anoxygenic phototrophic bacteria Roseobacter and Erythrobacter strains.

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.

Rhodovulum bhavnagarense sp. nov., a phototrophic alphaproteobacterium isolated from a pink pond.

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)).

Rhodoplanes piscinae sp. nov. isolated from pond water.

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.

Pseudorhodobacter aquimaris sp. nov., isolated from seawater, and emended description of the genus Pseudorhodobacter Uchino et al. 2002.

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)).

[Fingerprinting analysis of photopigments in purple bacteria].

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.

Distribution and growth of aerobic anoxygenic phototrophs in the Mediterranean Sea.

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.