Significant and variable linear polarization during the prompt optical flash of GRB 160625B.

Newly formed black holes of stellar mass launch collimated outflows (jets) of ionized matter that approach the speed of light. These outflows power prompt, brief and intense flashes of γ-rays known as γ-ray bursts (GRBs), followed by longer-lived afterglow radiation that is detected across the electromagnetic spectrum. Measuring the polarization of the observed GRB radiation provides a direct probe of the magnetic fields in the collimated jets. Rapid-response polarimetric observations of newly discovered bursts have probed the initial afterglow phase, and show that, minutes after the prompt emission has ended, the degree of linear polarization can be as high as 30 per cent-consistent with the idea that a stable, globally ordered magnetic field permeates the jet at large distances from the central source. By contrast, optical and γ-ray observations during the prompt phase have led to discordant and often controversial results, and no definitive conclusions have been reached regarding the origin of the prompt radiation or the configuration of the magnetic field. Here we report the detection of substantial (8.3 ± 0.8 per cent from our most conservative simulation), variable linear polarization of a prompt optical flash that accompanied the extremely energetic and long-lived prompt γ-ray emission from GRB 160625B. Our measurements probe the structure of the magnetic field at an early stage of the jet, closer to its central black hole, and show that the prompt phase is produced via fast-cooling synchrotron radiation in a large-scale magnetic field that is advected from the black hole and distorted by dissipation processes within the jet.

Extremely 'vanadiphilic' multiply metal-resistant and halophilic aerobic anoxygenic phototrophs, strains EG13 and EG8, from hypersaline springs in Canada.

Two pinkish peach-colored strains of obligately aerobic phototrophic bacteria, EG13 and EG8, were isolated from a saline spring effluent stream in west central Manitoba, Canada. The strains possessed bacteriochlorophyll a incorporated into a typical purple bacterial light-harvesting complex 1 (870 nm) and reaction center (801 nm). Analysis of 16S rRNA gene sequences indicated 100% identity among the isolates and 99% similarity to Roseovarius tolerans EL-172(T). The strains were physiologically well adapted to high salinity (0-22%), fluctuating pH (7-12) and temperature (7-40 °C) of the exposed hypersaline stream of East German Creek. EG8 and EG13 were also highly resistant to the toxic metal(loid) oxyanions tellurite, selenite and metavanadate (≥1000 µg/ml each). Most intriguingly, growth and pigment production of EG13 on glutamate minimal medium was stimulated by 1000-10000 µg/ml of sodium metavanadate compared to metal-free conditions. Phylogenetic analysis and phenotypic properties such as pigment composition and morphology indicate close relatedness to Roseovarius genus.

Chromocurvus halotolerans gen. nov., sp. nov., a gammaproteobacterial obligately aerobic anoxygenic phototroph, isolated from a Canadian hypersaline spring.

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.

An alphaproteobacterium capable of both aerobic and anaerobic anoxygenic photosynthesis but incapable of photoautotrophy: Charonomicrobium ambiphototrophicum, gen. nov., sp. nov.

A facultatively aerobic deep brown coccoid to ovoid bacterium, strain EG17(T), was isolated from a saline effluent stream in the NaCl-dominated brine spring system known as East German Creek in the province of Manitoba, Canada. The strain produced BChl a incorporated into a functional reaction center and two light-harvesting complexes with absorption peaks at 802, 850, and 879 nm. EG17(T) is the first reported anoxygenic phototroph capable of photoheterotrophic growth under both oxic and anoxic conditions. It yielded proportionally the greatest aerobic photosynthetic biomass under oligotrophic conditions. The results of 16S rRNA gene sequence comparisons revealed that EG17(T) was related most closely to the aerobic anoxygenic phototrophs Roseibacterium elongatum (98.3%) and quite distantly to both Dinoroseobacter shibae (95.2%) and Roseicyclus mahoneyensis (94.7%). The DNA G + C content was 65.6 mol%. On the basis of the unique dual aerobic/anaerobic photosynthetic capability, the distinctive spectrophotometric absorption of the photosynthetic apparatus, diagnostic physiological and biochemical traits, and the moderate phylogenetic separation between EG17(T) and its nearest relatives, it is concluded that this microorganism should be classified as a novel genus and species, Charonomicrobium ambiphototrophicum gen. nov., sp. nov., with EG17(T) as the type strain.

Proton transfer through the membrane-water interfaces in uncoupled mitochondria.

Increase in maximal respiration rate of uncoupled mitochondria in response to increase in concentration of non-penetrating buffer has been demonstrated. This phenomenon did not depend on chemical structure of uncouplers and composition of the non-penetrating buffer. Use of covalently attached pH probe, FITC, revealed that at low buffer concentration (3 mM) the H(+)-pump functioning results in local increase in proton concentration on the outer surface of the inner mitochondrial membranes. In other words, local H(+) gradient was generated. Increase in buffer concentration up to 20 mM caused sharp decrease in this gradient, which occurred in parallel to increase in the respiration rate. It is concluded that both effects described here may be attributed to the process of proton transfer through the interfaces of the mitochondrial membrane: the rate of respiratory H(+) pumps of uncoupled mitochondria under conditions of low buffer capacity of medium is limited by the stage of proton release from outer surface of the coupling membrane. The inhibition mechanism of respiration by high concentrations of uncouplers is also discussed.

Certain species of the Proteobacteria possess unusual bacteriochlorophyll a environments in their light-harvesting proteins.

In this work, we have examined, using Fourier-transform Raman (FT-R) spectroscopy, the bacteriochlorophyll a (BChl a) binding sites in light-harvesting (LH) antennae from different species of the Proteobacteria that exhibit unusal absorption properties. While the LH1 complexes from Erythromicrobium (E.) ramosum (RC-B871) and Rhodospirillum centenum (B875) present classic FT-R spectra in the carbonyl high-frequency region, we show that in the blue-shifted LH1 complex, absorbing at 856 nm, from Roseococcus thiosulfatophilus, as well as in the B798-832 LH2 from E. ramosum, or in the B830 complex from the obligate phototrophic bacterium Chromatium purpuratum, some H-bonds between the acetyl carbonyl of the BChl a and the surrounding protein are missing. The molecular mechanisms responsible for the unusual absorption of these complexes are thus similar to those responsible for tuning of the absorption of the LH2 complexes between 850 and 820 nm. Furthermore, our results suggest that the binding pocket of the monomeric BChl in the LH2 from E. ramosum is different from that of Rps. acidphila or Rb. sphaeroides. The FT-R spectra of Chromatium purpuratum indicate that, in contrast with every LH2 complex previously studied by FT-R spectroscopy, no free-from-interaction keto groupings exist in this complex.

Citromicrobium bathyomarinum, a novel aerobic bacterium isolated from deep-sea hydrothermal vent plume waters that contains photosynthetic pigment-protein complexes.

We have taxonomically and phylogenetically characterized a new aerobic bacterial strain (JF-1) that contains photosynthetic pigment-protein complexes and which was recently isolated from black smoker plume waters of the Juan de Fuca Ridge. Strain JF-1 is a gram-negative, yellow-pigmented, motile bacterium that is salt-, pH-, and thermotolerant. These properties are consistent with an oligotrophic adaptation to varied environmental conditions thought to exist around deep-sea hydrothermal vents. The analysis of 16S rDNA sequences revealed that strain JF-1 forms a separate phylogenetic branch between the genus Erythromonas and the Erythromicrobium-Porphyrobacter-Erythrobacter cluster within the alpha subclass of the Proteobacteria. The taxonomic name Citromicrobium bathyomarinum (gen. nov., sp. nov.) is proposed for strain JF-1.

Aerobic anoxygenic phototrophic bacteria.

The aerobic anoxygenic phototrophic bacteria are a relatively recently discovered bacterial group. Although taxonomically and phylogenetically heterogeneous, these bacteria share the following distinguishing features: the presence of bacteriochlorophyll a incorporated into reaction center and light-harvesting complexes, low levels of the photosynthetic unit in cells, an abundance of carotenoids, a strong inhibition by light of bacteriochlorophyll synthesis, and the inability to grow photosynthetically under anaerobic conditions. Aerobic anoxygenic phototrophic bacteria are classified in two marine (Erythrobacter and Roseobacter) and six freshwater (Acidiphilium, Erythromicrobium, Erythromonas, Porphyrobacter, Roseococcus, and Sandaracinobacter) genera, which phylogenetically belong to the alpha-1, alpha-3, and alpha-4 subclasses of the class Proteobacteria. Despite this phylogenetic information, the evolution and ancestry of their photosynthetic properties are unclear. We discuss several current proposals for the evolutionary origin of aerobic phototrophic bacteria. The closest phylogenetic relatives of aerobic phototrophic bacteria include facultatively anaerobic purple nonsulfur phototrophic bacteria. Since these two bacterial groups share many properties, yet have significant differences, we compare and contrast their physiology, with an emphasis on morphology and photosynthetic and other metabolic processes.

Isolation of aerobic anoxygenic photosynthetic bacteria from black smoker plume waters of the juan de fuca ridge in the pacific ocean.

A strain of the aerobic anoxygenic photosynthetic bacteria was isolated from a deep-ocean hydrothermal vent plume environment. The in vivo absorption spectra of cells indicate the presence of bacteriochlorophyll a incorporated into light-harvesting complex I and a reaction center. The general morphological and physiological characteristics of this new isolate are described.

Reorganization of the genus Erythromicrobium: description of "Erythromicrobium sibiricum" as Sandaracinobacter sibiricus gen. nov., sp. nov., and of "Erythromicrobium ursincola" as Erythromonas ursincola gen. nov., sp. nov.

The results of investigations on the morphology, physiology, pigment composition, light-harvesting antenna and reaction center organization, and electron carriers of five Erythromicrobium representatives, and on phylogenetic relations among them, are summarized. On the basis of clear phenotypic differences and distinct phylogenetic positions shown by 16S ribosomal DNA analysis, the tentative species "Erythromicrobium sibiricum" and "Erythromicrobium ursincola" are formally described as the type species of two new genera: Sandaracinobacter sibiricus gen. nov., sp. nov., and Erythromonas ursincola gen. nov., sp. nov., respectively. The genus Erythromicrobium is at present composed of the type species, E. ramosum, and two species, "E. hydrolyticum" and "E. ezovicum," whose nomenclature is yet to be validated. All species studied group within the alpha-4 subclass of Proteobacteria.

Tellurite resistance and reduction by obligately aerobic photosynthetic bacteria.

Seven species of obligately aerobic photosynthetic bacteria of the genera Erythromicrobium, Erythrobacter, and Roseococcus demonstrated high-level resistance to tellurite and accumulation of metallic tellurium crystals. High-level resistance without tellurite reduction was observed for Roseococcus thiosulfatophilus and Erythromicrobium ezovicum grown with certain organic carbon sources, implying that tellurite reduction is not essential to confer tellurite resistance.

Phylogenetic positions of novel aerobic, bacteriochlorophyll a-containing bacteria and description of Roseococcus thiosulfatophilus gen. nov., sp. nov., Erythromicrobium ramosum gen. nov., sp. nov., and Erythrobacter litoralis sp. nov.

We analyzed the 16S ribosomal DNAs of three obligately aerobic, bacteriochlorophyll a-containing bacteria, "Roseococcus thiosulfatophilus," "Erythromicrobium ramosum," and new isolate T4T (T = type strain), which was obtained from a marine cyanobacterial mat. "Roseococcus thiosulfatophilus" is a member of the alpha-1 subclass of the Proteobacteria and is moderately related to Rhodopila globiformis, Thiobacillus acidophilus, and Acidiphilium cryptum (level of sequence similarity, 90%). "Erythromicrobium ramosum" and isolate T4T are closely related to Erythrobacter longus and Porphyrobacter neustonensis (level of sequence similarity, 95%). These organisms are members of the alpha-4 subclass of the Proteobacteria. Strain T4T is a motile, red or orange bacterium. The major carotenoids are bacteriorubixanthinal and erythroxanthin sulfate. In vivo measurements revealed bacteriochlorophyll absorption maxima at 377, 590, 800, and 868 nm. Strain T4T grows in the presence of 5 to 96/1000 salinity and uses glucose, fructose, acetate, pyruvate, glutamate, succinate, and lactate as substrates. On the basis of its distinct phylogenetic position and phenotypic characteristics which are different from those of Erythrobacter longus, we propose that strain T4T should be placed in a new species of the genus Erythrobacter, Erythrobacter litoralis. The descriptions of "Roseococcus thiosulfatophilus" and "Erythromicrobium ramosum" are emended.