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Armen Trchounian - One of the best experts on this subject based on the ideXlab platform.

  • yeast extract as an effective nitrogen source stimulating cell growth and enhancing hydrogen photoproduction by rhodobacter sphaeroides strains from Mineral Springs
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Lilit Hakobyan, Lilit Gabrielyan, Armen Trchounian
    Abstract:

    Abstract The suitability and limitation of yeast extract as nitrogen source to support cell growth and to enhance hydrogen photoproduction by Rhodobacter sphaeroides strains MDC6521 and MDC6522 isolated from Mineral Springs in Armenia was investigated during the anaerobic growth. Yeast extract (2 g L−1) was indicated to be an effective nitrogen source for bacterial cell growth stimulation and enhanced H2 production (compared to glutamate). Both strains followed similar growth patterns in medium with yeast extract as nitrogen source and succinate or malate as carbon source. The highest growth rate was obtained for bacterial cells with yeast extract: the latter added gave a stimulated (2–3.5 fold) growth rate than using glutamate. R. sphaeroides suspension oxidation–reduction potential (ORP), which was measured with a platinum electrode, decreased down to low negative values with nitrogen source for both strains. ORP decreased down to more negative values (−610 ± 25 mV) in the presence of yeast extract than when adding glutamate (−405 ± 15 mV) compared to the control (without nitrogen source addition): the significant decrease of ORP indicated enhanced (∼6 fold) H2 yield. The noticeable ORP decrease measured with the titanium-silicate electrode and simultaneously the increase of extracellular pH ([pH]out) were observed; ORP was more negative at alkaline [pH]out. Thus, the optimal culture conditions with nitrogen and carbon sources for bacterial growth stimulation and enhanced H2 production were established. The ORP decrease together with the increase of [pH]out point out a significant role of reduction processes in cell growth and ability of bacteria to live.

  • Concentration dependent glycine effect on the photosynthetic growth and bio-hydrogen production by Rhodobacter sphaeroides from Mineral Springs
    Biomass and Bioenergy, 2012
    Co-Authors: Lilit Gabrielyan, Armen Trchounian
    Abstract:

    Abstract The effect of glycine as nitrogen source on growth and H 2 production by purple non-sulfur bacterium Rhodobacter sphaeroides MDC 6521 (isolated from Mineral Springs in Armenia) in the presence of succinate as the carbon source was investigated. Growth rate, light absorption spectra, medium pH and oxidation-reduction potential (ORP) variation during bacterial anaerobic growth upon illumination were examined. At the presence of glycine the specific growth rate decreased significantly in comparison with control (∼25% for 5 mol m −3 or 7 mol m −3 glycine and ∼60% for 10 mol m −3 glycine). The culture initial pH 7.0 increased to ∼8.3, when 5 mol m −3 glycine was used. At the presence of 7 mol m −3 or 10 mol m −3 glycine pH was not changed much: pH raises to ∼7.6. ORP of R. sphaeroides gradually decreased to negative (−580 mV ± 20 mV) value during the growth at the presence of 5 mol m −3 glycine, indicating H 2 production. 10 mol m −3 glycine did not provide H 2 production (ORP decreased to −40 mV ± 5 mV). The results point out the concentration dependent glycine effect: 5 mol m −3 glycine can serve as nitrogen source for growth and H 2 production by R. sphaeroides ; however 10 mol m −3 glycine suppressed growth and H 2 production. This might be applied when glycine or other amino acids are used as nitrogen sources in bio-hydrogen technology with photosynthetic bacteria.

  • Ni (II) and Mg (II) ions as factors enhancing biohydrogen production by Rhodobacter sphaeroides from Mineral Springs
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Lilit Hakobyan, Lilit Gabrielyan, Armen Trchounian
    Abstract:

    Abstract Various metal ions play a key role in biohydrogen (H 2 ) production by phototrophic bacteria through incorporation into or stimulating the responsible enzymes and/or related pathways. The Ni (II) and Mg (II) ions effects on growth and H 2 production by Rhodobacter sphaeroides strain MDC6521 isolated from Mineral Springs in Armenia were established. The highest growth specific rate was obtained with 4–6 μM Ni 2+ and 5 mM Mg 2+ . pH of the growth medium changed from 7.0 to 9.2–9.4 during the bacterial growth up to 72 h in spite of Ni 2+ added but pH increased in different manner with Mg 2+ . In the presence of 2–4 μM Ni 2+ external oxidation-reduction potential (ORP) decreased to more negative values (−800 ± 15 mV). This decrease of ORP indicated ∼2.7-fold enhanced H 2 yield (9.80 mmol L −1 ) with Ni 2+ compared with the control (without Ni 2+ ). The H 2 yield determined in the medium with Mg 2+ was ∼2.2 fold higher than that with 1 mM Mg 2+ . These results reveal new regulatory ways to improve H 2 production by R. sphaeroides those were depending on Ni 2+ and Mg 2+ of different concentrations.

  • relationship between molecular hydrogen production proton transport and the f0f1 atpase activity in rhodobacter sphaeroides strains from Mineral Springs
    International Journal of Hydrogen Energy, 2009
    Co-Authors: Lilit Gabrielyan, Armen Trchounian
    Abstract:

    This article aims to study hydrogen production and proton transport in two strains of purple non-sulfur bacterium Rhodobacter sphaeroides isolated from Mineral Springs of Armenia. This bacterium is able to grow and produce molecular hydrogen (H2) in anaerobic conditions upon illumination. Along with H2 production, a marked decrease in redox potential and the alkalization of the medium have been observed; the latter might be the evidence of proton influx. H2 production and alkalization of the medium by whole cells both are suppressed by the F0F1-ATPase inhibitors – N,N′-dicyclohexylcarbodiimide (DCCD), sodium azide (NaN3) and protonophore – carbonyl cyanide m-chlorophenylhydrazone (CCCP). Membrane vesicles of two strains of R. sphaeroides demonstrate ATPase activity, inhibited by DCCD and NaN3, but not by CCCP. These results indicate a relationship between H2 production, proton transport and the F0F1-ATPase activity that might be a pathway to regulate bacterial activity under anaerobic conditions.

Horst Kämpf - One of the best experts on this subject based on the ideXlab platform.

  • the gas flow at Mineral Springs and mofettes in the vogtland nw bohemia an enduring long term increase
    Geofluids, 2008
    Co-Authors: Ulrich Koch, Karin Bräuer, J. Heinicke, Horst Kämpf
    Abstract:

    Over the last 15 years, there has been an increase in the 3He/4He ratios (Ra) at gas emission sites including Springs (liquid-dominated) and mofettes (gas-dominated) in the Vogtland (Germany) and NW Bohemia (Czech Republic), indicating an active magmatic process. The highest Ra value (6.2) was measured at the mofette Bublak. Continuous CO2 flow records at Bad Brambach Mineral Springs (Vogtland) and Cheb Basin mofettes show a significant and enduring increase in gas flow. This increase ranges from 1.6% at Schillerquelle spring, Bad Brambach, and 61% per year at mofette Bublak. Calculated gas flow ratios between the individual emission sites not only emphasize the greater increase in gas flow over time at the Cheb Basin mofettes compared with the Bad Brambach Springs (factor 2.1 to 2.6) but also show a uniform gas flow behaviour within both emission areas. Using simplified models, it is demonstrated that long-term gas flow measurements reveal a gas-hydraulic parameter, the effective cross-sectional ratio, to compare the near-surface gas-bearing fissures and cracks between the emission sites. Thus, the overall cross-sectional area of gas pathways at the mofette Soos is 13.2 times higher than at the Wettinquelle spring, indicating greater overall fissure widths for gas transport at the Cheb Basin mofettes than at the Mineral Springs. Comparison between the monthly fluctuations of free gas flow and dissolved CO2 at the Wettinquelle spring shows an inverse dependence of both parameters but without a temporal trend of dissolved CO2. This indicates that the Mineral water body acts as a kind of buffer saturated by CO2 and being degassed more or less strongly, depending on the flow rate of the ascending free gas. The results suggest increased activity of the magmatic reservoir below the Cheb Basin, not only from the qualitative (3He/4He) but also from the quantitative (amount of magmatic CO2) perspective.

  • The gas flow at Mineral Springs and mofettes in the Vogtland/NW Bohemia: an enduring long‐term increase
    Geofluids, 2008
    Co-Authors: Ulrich Koch, Karin Bräuer, J. Heinicke, Horst Kämpf
    Abstract:

    Over the last 15 years, there has been an increase in the 3He/4He ratios (Ra) at gas emission sites including Springs (liquid-dominated) and mofettes (gas-dominated) in the Vogtland (Germany) and NW Bohemia (Czech Republic), indicating an active magmatic process. The highest Ra value (6.2) was measured at the mofette Bublak. Continuous CO2 flow records at Bad Brambach Mineral Springs (Vogtland) and Cheb Basin mofettes show a significant and enduring increase in gas flow. This increase ranges from 1.6% at Schillerquelle spring, Bad Brambach, and 61% per year at mofette Bublak. Calculated gas flow ratios between the individual emission sites not only emphasize the greater increase in gas flow over time at the Cheb Basin mofettes compared with the Bad Brambach Springs (factor 2.1 to 2.6) but also show a uniform gas flow behaviour within both emission areas. Using simplified models, it is demonstrated that long-term gas flow measurements reveal a gas-hydraulic parameter, the effective cross-sectional ratio, to compare the near-surface gas-bearing fissures and cracks between the emission sites. Thus, the overall cross-sectional area of gas pathways at the mofette Soos is 13.2 times higher than at the Wettinquelle spring, indicating greater overall fissure widths for gas transport at the Cheb Basin mofettes than at the Mineral Springs. Comparison between the monthly fluctuations of free gas flow and dissolved CO2 at the Wettinquelle spring shows an inverse dependence of both parameters but without a temporal trend of dissolved CO2. This indicates that the Mineral water body acts as a kind of buffer saturated by CO2 and being degassed more or less strongly, depending on the flow rate of the ascending free gas. The results suggest increased activity of the magmatic reservoir below the Cheb Basin, not only from the qualitative (3He/4He) but also from the quantitative (amount of magmatic CO2) perspective.

Paul Aharon - One of the best experts on this subject based on the ideXlab platform.

  • Beggiatoa in microbial mats at hydrocarbon vents in the Gulf of Mexico and Warm Mineral Springs, Florida
    Geo-Marine Letters, 1994
    Co-Authors: John Larkin, Margaret C. Henk, Paul Aharon
    Abstract:

    Microbial mats were collected from a variety of sites near hydrocarbon vents along the slope in the northern Gulf of Mexico and, for comparison, from Warm Mineral Springs, Florida, USA. A predominant microorganism in each of the mats was the giant bacterium, Beggiatoa. Diameters of the bacterial filaments ranged from about 6 µm to approximately 200 µm. The latter organisms are the largest prokaryotic organisms yet found. All filaments over about 10 µm in diameter contained a large central vacuole, producing a cell with the cytoplasm as a cylindrical tube underlying the cytoplasmic membrane. Sulfur globules were confined to this peripheral layer. Push cores often contained pyrite tubules whose appearance is suggestive of a Beggiatoa origin. Determinations of δ ^13C in Beggiatoa mats from vents along the Louisiana slope yielded values in the range of −26.6 to −27.9‰ (PDB), suggesting an unusually high degree of isotope fractionation (−24.9‰) relative to the carbon source in the ambient seawater, which is typical of sulfur-oxidizing chemoautotrophs. The presence of S^O (elemental sulfur) within cells of Beggiatoa resulting from oxidation of H_2S supports the importance of bacterial sulfate reduction processes in the underlying vents for the sustenance of the Beggiatoa mats.

Lilit Gabrielyan - One of the best experts on this subject based on the ideXlab platform.

  • yeast extract as an effective nitrogen source stimulating cell growth and enhancing hydrogen photoproduction by rhodobacter sphaeroides strains from Mineral Springs
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Lilit Hakobyan, Lilit Gabrielyan, Armen Trchounian
    Abstract:

    Abstract The suitability and limitation of yeast extract as nitrogen source to support cell growth and to enhance hydrogen photoproduction by Rhodobacter sphaeroides strains MDC6521 and MDC6522 isolated from Mineral Springs in Armenia was investigated during the anaerobic growth. Yeast extract (2 g L−1) was indicated to be an effective nitrogen source for bacterial cell growth stimulation and enhanced H2 production (compared to glutamate). Both strains followed similar growth patterns in medium with yeast extract as nitrogen source and succinate or malate as carbon source. The highest growth rate was obtained for bacterial cells with yeast extract: the latter added gave a stimulated (2–3.5 fold) growth rate than using glutamate. R. sphaeroides suspension oxidation–reduction potential (ORP), which was measured with a platinum electrode, decreased down to low negative values with nitrogen source for both strains. ORP decreased down to more negative values (−610 ± 25 mV) in the presence of yeast extract than when adding glutamate (−405 ± 15 mV) compared to the control (without nitrogen source addition): the significant decrease of ORP indicated enhanced (∼6 fold) H2 yield. The noticeable ORP decrease measured with the titanium-silicate electrode and simultaneously the increase of extracellular pH ([pH]out) were observed; ORP was more negative at alkaline [pH]out. Thus, the optimal culture conditions with nitrogen and carbon sources for bacterial growth stimulation and enhanced H2 production were established. The ORP decrease together with the increase of [pH]out point out a significant role of reduction processes in cell growth and ability of bacteria to live.

  • Concentration dependent glycine effect on the photosynthetic growth and bio-hydrogen production by Rhodobacter sphaeroides from Mineral Springs
    Biomass and Bioenergy, 2012
    Co-Authors: Lilit Gabrielyan, Armen Trchounian
    Abstract:

    Abstract The effect of glycine as nitrogen source on growth and H 2 production by purple non-sulfur bacterium Rhodobacter sphaeroides MDC 6521 (isolated from Mineral Springs in Armenia) in the presence of succinate as the carbon source was investigated. Growth rate, light absorption spectra, medium pH and oxidation-reduction potential (ORP) variation during bacterial anaerobic growth upon illumination were examined. At the presence of glycine the specific growth rate decreased significantly in comparison with control (∼25% for 5 mol m −3 or 7 mol m −3 glycine and ∼60% for 10 mol m −3 glycine). The culture initial pH 7.0 increased to ∼8.3, when 5 mol m −3 glycine was used. At the presence of 7 mol m −3 or 10 mol m −3 glycine pH was not changed much: pH raises to ∼7.6. ORP of R. sphaeroides gradually decreased to negative (−580 mV ± 20 mV) value during the growth at the presence of 5 mol m −3 glycine, indicating H 2 production. 10 mol m −3 glycine did not provide H 2 production (ORP decreased to −40 mV ± 5 mV). The results point out the concentration dependent glycine effect: 5 mol m −3 glycine can serve as nitrogen source for growth and H 2 production by R. sphaeroides ; however 10 mol m −3 glycine suppressed growth and H 2 production. This might be applied when glycine or other amino acids are used as nitrogen sources in bio-hydrogen technology with photosynthetic bacteria.

  • Ni (II) and Mg (II) ions as factors enhancing biohydrogen production by Rhodobacter sphaeroides from Mineral Springs
    International Journal of Hydrogen Energy, 2012
    Co-Authors: Lilit Hakobyan, Lilit Gabrielyan, Armen Trchounian
    Abstract:

    Abstract Various metal ions play a key role in biohydrogen (H 2 ) production by phototrophic bacteria through incorporation into or stimulating the responsible enzymes and/or related pathways. The Ni (II) and Mg (II) ions effects on growth and H 2 production by Rhodobacter sphaeroides strain MDC6521 isolated from Mineral Springs in Armenia were established. The highest growth specific rate was obtained with 4–6 μM Ni 2+ and 5 mM Mg 2+ . pH of the growth medium changed from 7.0 to 9.2–9.4 during the bacterial growth up to 72 h in spite of Ni 2+ added but pH increased in different manner with Mg 2+ . In the presence of 2–4 μM Ni 2+ external oxidation-reduction potential (ORP) decreased to more negative values (−800 ± 15 mV). This decrease of ORP indicated ∼2.7-fold enhanced H 2 yield (9.80 mmol L −1 ) with Ni 2+ compared with the control (without Ni 2+ ). The H 2 yield determined in the medium with Mg 2+ was ∼2.2 fold higher than that with 1 mM Mg 2+ . These results reveal new regulatory ways to improve H 2 production by R. sphaeroides those were depending on Ni 2+ and Mg 2+ of different concentrations.

  • relationship between molecular hydrogen production proton transport and the f0f1 atpase activity in rhodobacter sphaeroides strains from Mineral Springs
    International Journal of Hydrogen Energy, 2009
    Co-Authors: Lilit Gabrielyan, Armen Trchounian
    Abstract:

    This article aims to study hydrogen production and proton transport in two strains of purple non-sulfur bacterium Rhodobacter sphaeroides isolated from Mineral Springs of Armenia. This bacterium is able to grow and produce molecular hydrogen (H2) in anaerobic conditions upon illumination. Along with H2 production, a marked decrease in redox potential and the alkalization of the medium have been observed; the latter might be the evidence of proton influx. H2 production and alkalization of the medium by whole cells both are suppressed by the F0F1-ATPase inhibitors – N,N′-dicyclohexylcarbodiimide (DCCD), sodium azide (NaN3) and protonophore – carbonyl cyanide m-chlorophenylhydrazone (CCCP). Membrane vesicles of two strains of R. sphaeroides demonstrate ATPase activity, inhibited by DCCD and NaN3, but not by CCCP. These results indicate a relationship between H2 production, proton transport and the F0F1-ATPase activity that might be a pathway to regulate bacterial activity under anaerobic conditions.

John Walton - One of the best experts on this subject based on the ideXlab platform.

  • Family firm, health resort and industrial colony: The grand hotel and Mineral Springs at Mondariz Balneario, Spain, 1873–1932
    Business History, 2014
    Co-Authors: John Walton
    Abstract:

    There is a considerable literature on histories of family businesses, but very little dealing with the tourism and hospitality sector, despite growing recognition of its importance. This case study of a Spanish Mineral Springs resort between the 1870s and the 1930s sets the trajectory of Mondariz Balneario, Galicia, a family-run spa hotel with an elite clientele, in national and international context. It seeks to explain the resort's inter-generational success in terms of amenity, paternalism, imaginative publicity and networking, and a conscious quest for what would later be called sustainability, with added ingredients of Galician cultural patriotism and integration into the wider regional economy.

  • Mineral Springs resorts in global perspective spa histories
    2014
    Co-Authors: John Walton
    Abstract:

    1. Introduction: Health, sociability, politics and culture: spas in history, spas and history 2. Scarborough in the 1730s: spa, sea and sex 3. Town or country? British spas and the urban/ rural interface 4. Visitors and residents: the dynamics of charity in eighteenth-century Bath 5. A fading movement: hydrotherapy at the Scottish Hydros, 1840-1939 6. The value of water: the origins and expansion of thermal tourism in Spain 7. Moral economies and commercial imperatives: food, diets and spas in Central Europe, 1800-1914 8. Spas, steamships and sardines: Edwardian package tourism and the marketing of Galician regionalism 9. Reinventions of a spa town: the unique case of Vichy 10. Saratoga Springs: from genteel spa to Disneyfied family resort 11. From the majestic to the mundane: democracy, sophistication and history among the Mineral spas of Australia