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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 107 (1985), S. 7183-7184 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 57 (1935), S. 863-866 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Microbial ecology 33 (1997), S. 69 -77 
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Viable counts and potential activities of different bacteria were determined as a function of depth in the deep profundal sediment of Lake Constance, Germany. The sediment layer at the bottom of the lake had a total depth of about 7 m and was deposited in the time after the last ice age, i.e., over the past 13,000 years. The high clay content of the sediment prevents seepage. Below 25 cm all of the viable heterotrophic bacteria were present as heat-resistant spores. Numbers of viable spores of both aerobic and anaerobic heterotrophic bacteria decreased exponentially with sediment depth and were below the detection limit (5–55 cells ml−1) at 4–6 m, i.e., in about 8,900-year-old sediment. Absence of viable heterotrophic bacteria in deeper sediment layers demonstrated that aseptic sampling conditions were achieved. The decrease of viable spores with depth may be interpreted as time-dependent death of spores resulting in a death rate of about 0.0013–0.0025 year−1. Viable units of specific metabolic groups of bacteria were detected only in the upper sediment layers (0–50 cm). Nitrifying bacteria could not be detected below 30 cm. Methane-oxidizing bacteria were present in the sediment down to 〉30 cm, but were in a dormant state. Nitrate reduction activity decreased by a factor of 6 within the upper 25 cm of the sediment, but was still detected at 50 cm. Sulfate reduction, on the other hand, could not be detected at depths of 20 cm and below. By contrast, methanogenesis and methanogenic bacteria could be detected down to 50 cm. These observations indicate that bacteria eventually become nonviable in aged sediments.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 11 (1991), S. 38-42 
    ISSN: 1432-0789
    Keywords: Nitric oxide ; Nitrous oxide ; Denitrifiers ; Nitrifiers ; Compensation concentrations ; Uptake rate constants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary NO and N2O release rates were measured in an acidic forest soil (pH 4.0) and a slightly alkaline agricultural soil (pH 7.8), which were incubated at different O2 concentrations (〈0.01 – 20% O2) and at different NO concentrations (40 – 1000 ppbv NO). The system allowed the determination of simultaneously operating NO production rates and NO uptake rate constants, and the calculation of a NO compensation concentration. Both NO production and NO consumption decreased with increasing O2. NO consumption decreased to a smaller extent than NO production, so that the NO compensation concentrations also decreased. However, the NO compensation concentrations were not low enough for the soils to become a net sink for atmospheric NO. The release of N2O increased relative to NO release when the gases were allowed to accumulate instead of being flushed out. The forest soil contained only denitrifying, but not nitrifying bacteria, whereas the agricultural soil contained both. Nevertheless, NO release rates were less sensitive to O2 in the forest soil compared to the agricultural soil.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 11 (1991), S. 190-195 
    ISSN: 1432-0789
    Keywords: Knallgas bacteria ; Soil enzymes ; H2 oxidation kinetics ; Uptake hydrogenase (hup) ; Acetylene reduction assay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary The rate of H2 release from broad beans (Vicia faba) infected with Rhizobium leguminosarum Hup- was much faster than from beans infected with the Hup+ strain. Acetylene reduction and H2 release were abolished by cutting the plants down, by incubation in darkness, or after the addition of ammonium, indicating that the H2 was released by N2-fixing bacterial symbionts. In laboratory cultures using non-sterile soil, the bean plants released H2 until an equilibrium between H2 production and H2 oxidation was reached. The H2 equilibrium concentration was higher in Hup--infected bean cultures (about 3 ppm H2 in the gas phase) than in Hup+-infected cultures (0.3 ppm H2) because of the higher H2 production. The H2 release from Hup--infected bean cultures in sterile soil did not reach equilibrium. An equilibrium occurred, if Knallgas bacteria were added. However, the equilibrium value was higher (13 ppm H2) than in non-sterile soil, which seemed to be more efficient at H2 oxidation. The Knallgas bacteria exhibited a relatively high K m for H2 (〉 1300 ppmv H2); this activity was observed in unplanted non-sterile soil, and in nonsterile soil planted with Hup+-infected beans or planted with Hup--infected beans which had been cut down before being assayed. All these soils also showed a second, low-K m (〈50 ppm) level of H2 oxidation activity, which was presumably due to abiontic soil enzymes. In contrast, only one level of activity, which had an intermediate K m (about 200 ppm H2), was observed when the soil was planted with Hup--infected beans. The origin of this activity, which was only observed in the presence of intact, H2-producing beans, is still unknown.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 21 (1996), S. 152-159 
    ISSN: 1432-0789
    Keywords: Thiosulfate ; Tetrathionate ; Carbonyl sulfide ; Carbon disulfide ; Nitrate ; Nitrite ; Nitric oxide ; Nitrous oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thiosulfate and CS2 inhibit nitrification. The effect of the addition of thiosulfate on the turnover of inorganic N compounds was tested in an Egyptian and a German arable soil under nitrifying and denitrifying conditions. For nitrification, the soils were amended with NH inf4 sup+ and incubated under aerobic conditions. For denitrification, the soils were amended with NO inf3 sup- and incubated under anaerobic conditions. In both cases, the thiosulfate decreased with time while tetrathionate accumulated to an intermediate extent. Both compounds disappeared completely after 〈25 days. Production of CS2 was not observed. Carbonyl sulfide was produced only in the Egyptian soil, but production decreased with increasing amounts of added thiosulfate. Under nitrifying conditions, the addition of increasing amounts of thiosulfate (25, 50, and 100 μg S g-1 dry weight) resulted in decreasing rates of NH inf4 sup+ oxidation to NO inf3 sup- ; it also resulted in an increasing intermediate accumulation of NO inf2 sup- and NO, and in an increasing production of N2O. Under denitrifying conditions, the addition of increasing amounts of thiosulfate did not significantly affect the rate of NO inf3 sup- reduction, and resulted in an increasing intermediate accumulation of NO inf2 sup- and of NO only in the German soil in which the production of N2O was slightly inhibited by thiosulfate. These results demonstrate that the nitrification of NH inf4 sup+ and NO inf2 sup- was inhibited by increasing concentrations of thiosulfate and/or tetrathionate without involving the formation of volatile S compounds as potential nitrification inhibitors. Denitrification was not affected by the addition of thiosulfate.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 21 (1996), S. 152-159 
    ISSN: 1432-0789
    Keywords: Key words Thiosulfate ; Tetrathionate ; Carbonyl sulfide ; Carbon disulfide ; Nitrate ; Nitrite ; Nitric oxide ; Nitrous oxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Thiosulfate and CS2 inhibit nitrification. The effect of the addition of thiosulfate on the turnover of inorganic N compounds was tested in an Egyptian and a German arable soil under nitrifying and denitrifying conditions. For nitrification, the soils were amended with NH and incubated under aerobic conditions. For denitrification, the soils were amended with NO and incubated under anaerobic conditions. In both cases, the thiosulfate decreased with time while tetrathionate accumulated to an intermediate extent. Both compounds disappeared completely after 〈25 days. Production of CS2 was not observed. Carbonyl sulfide was produced only in the Egyptian soil, but production decreased with increasing amounts of added thiosulfate. Under nitrifying conditions, the addition of increasing amounts of thiosulfate (25, 50, and 100 μg S g–1 dry weight) resulted in decreasing rates of NH oxidation to NO; it also resulted in an increasing intermediate accumulation of NO and NO, and in an increasing production of N2O. Under denitrifying conditions, the addition of increasing amounts of thiosulfate did not significantly affect the rate of NO reduction, and resulted in an increasing intermediate accumulation of NO and of NO only in the German soil in which the production of N2O was slightly inhibited by thiosulfate. These results demonstrate that the nitrification of NH and NO was inhibited by increasing concentrations of thiosulfate and/or tetrathionate without involving the formation of volatile S compounds as potential nitrification inhibitors. Denitrification was not affected by the addition of thiosulfate.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 18 (1994), S. 109-114 
    ISSN: 1432-0789
    Keywords: Soil hydrogenase ; ATP ; Bacterial counts ; Particle size fractionation ; Cambisol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Low atmospheric H2 concentrations (0.55 ppmv) are oxidized in soils by a high-affinity activity with typical characteristics of an abiontic soil enzyme. This activity was measured in a meadow cambisol and a forest cambisol. In both soils, the maximum activity was reached at a soil moisture of about 20% water-holding capacity, and was localized in the top Ah horizon. The soils were fractionated by dry sieving and wet filtration into nine different particle-size fractions, ranging from 3 to 2000 μm in size. H2 oxidation was measured by three different assays and was compared to the ATP content and microscopic counts of bacteria in the same fractions. In the meadow soil, the specific activities of H2 oxidation increased with the particle size (maximum at 200–500 μm), whereas ATP and bacterial counts showed no trend. In the forest soil, the specific activities of H2 oxidation increased with the particle size up to 50–100 μm, and then decreased again. ATP and bacterial counts, however, showed the opposite trend, i.e., decreased with an increasing particle size. Thus the H2-oxidizing activity was not correlated with characteristic microbial biomass parameters. Although significant percentage (29–64%) of randomly isolated heterotrophic bacteria was able to oxidize H2, this activity was too small to account for the H2 oxidation in the soil. In both soils, most of the activity present was found in particles of 100–500 μm in size. The recovery shifted to smaller size fractions when larger soil aggregates were broken up by wet instead of dry sieving. Attempts to extract the H2-oxidizing activity from the soil particles were unsuccessful.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 32 (2000), S. 129-134 
    ISSN: 1432-0789
    Keywords: Key words Atmospheric hydrogen ; Atmospheric carbon monoxide ; Soil organic carbon ; Substrate-induced respiration ; Multiple regression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract  Soils are the dominant sink in the global budget of atmospheric H2, and can be an important local source of atmospheric CO. In order to understand which soil characteristics affect the rates of H2 consumption and CO production, we measured these activities in 16 different soils at 30% and 60% of their maximum water holding capacity (whc). The soils were obtained from forests, meadows and agricultural fields in Germany and exhibited different characteristics with respect to texture, pH, total C, substrate-induced respiration (SIR), respiration, total and inorganic N, N mineralization, nitrification, N2O production and NO turnover. The H2 consumption rate constants were generally lower at 60% than at 30% whc, whereas the CO production rates were not influenced by the whc. Spearman correlation analysis showed that H2 consumption correlated significantly (r〉0.5, P〈0.05) at both water contents only with SIR and potential nitrification. The correlation with these variables that are largely dominated by soil microorganisms is consistent with our understanding that atmospheric H2 is oxidized by soil hydrogenases. Multiple regression analysis and factor analysis gave similar results. Production of CO, on the other hand, was significantly correlated to soil total C, respiration, total N and NH4 +. The correlation with these variables that are largely dominated by a soil's chemical composition is consistent with our understanding that CO is produced by chemical oxidation of soil organic C. CO production was also influenced by soil usage, with rates increasing in the order: arable〈meadow〈forest. H2 consumption was not influenced by soil usage.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 12 (1991), S. 127-130 
    ISSN: 1432-0789
    Keywords: Soil hydrogenase ; Knallgas bacteria ; pH optimum ; Temperature optimum ; Apparent activation energy ; Seasonal change
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Hydrogen oxidation in soil was measured at low (1 ppmv) and high (300 ppmv) H2 concentrations to distinguish between the activities of abiontic soil hydrogenases and Knallgas bacteria, respectively. The two activities also showed distinctly different pH optima, temperature optima, and apparent activation energies. The pH optima for the soil hydrogenase activities were similar to the soil pH in situ, i.e., pH 8 in an slightly alkaline garden soil (pH 7.3) and pH 5 in an acidic cambisol (pH 4.6–5.4). Most probable number determinations in the alkaline acidic soils showed that Knallgas bacterial populations grew preferentially in neutral or acidic media, respectively. However, H2 oxidation activity by Knallgas bacteria in the acidic soil showed two distinct pH optima, one at pH 4 and a second at pH 6.4–7.0. The soil hydrogenase activities exhibited temperature optima at 35–40°C, whereas the Knallgas bacteria had optima at 50–60°C. The apparent activation energies of the soil hydrogenases were lower (11–23kJ mol-1) than those of the Knallgas bacteria (51–145 kJ mol-1). Most of the soil hydrogenase activity was located in the upper 10 cm of the acidic cambisol and changed with season. The seasonal activity changes were correlated with changes in soil moisture and soil pH.
    Type of Medium: Electronic Resource
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