Nitrogen fixation and photosynthesis in high arctic forms of Nostoc commune

1994 ◽  
Vol 72 (7) ◽  
pp. 940-945 ◽  
Author(s):  
R. Lennihan ◽  
D. M. Chapin ◽  
L. G. Dickson
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
High Arctic ◽  
Colony Morphology ◽  
Nostoc Commune ◽  
Devon Island ◽  
Low Levels ◽  
Temperature Optima

Nostoc commune, a colonial cyanobacterium, has been suggested as an important contributor of nitrogen to terrestrial ecosystems in the Canadian High Arctic, yet little is known about the ecophysiology of this organism in arctic environments. This study focused on the physiological performance of macroscopic colonies of N. commune found on Devon Island, N.W.T. The objectives were to examine the influence of temperature, colony morphology, and seasonal phenology on nitrogen fixation rates and the effects of light and temperature on photosynthesis. Maximum rates of acetylene reduction in N. commune (2119 nmol C2H4∙g−1∙h−1) were higher than those previously recorded for arctic N. commune but lower than values reported for temperate poulations. Depending on the time of the growing season, the temperature optimum for acetylene reduction varied from 15 °C to greater than 20 °C. Photosynthetic temperature optima did not occur below 20–25 °C (the highest temperatures measured). Light saturation of photosynthesis was reached at low levels of irradiance (100–150 μmol∙m−2∙s−1 PPFD). Acetylene reduction rates varied strongly with colony morphology. Thin, fragile, flattened colonies had higher rates than thicker, more resilient, flattened colonies or spherical colonies. Cold post-thaw temperatures appeared to delay the recovery of maximum nitrogen fixation rates for 2–3 weeks following the onset of the growing season. Compared with two other species of cyanobacteria present on Truelove Lowland (Gloeocapsa alpina and Gleotrichia sp.), N. commune had higher rates of nitrogen fixation. Key words: Nostoc commune, cyanobacteria, High Arctic, nitrogen fixation, photosynthesis.

Environmental regulation of nitrogen fixation in a high arctic lowland ecosystem

1991 ◽  
Vol 69 (12) ◽  
pp. 2744-2755 ◽  
Author(s):  
David M. Chapin ◽  
L. C. Bliss ◽  
L. J. Bledsoe
Keyword(s):  
Nitrogen Fixation ◽  
Soil Moisture ◽  
Environmental Regulation ◽  
Acetylene Reduction ◽  
High Arctic ◽  
Spatial And Temporal Variation ◽  
Phosphorus Fertilization ◽  
Nostoc Commune ◽  
Nitrogen And Phosphorus ◽  
Devon Island

This study examined spatial and temporal variation in cyanobacterial nitrogen fixation and the environmental regulation of this variation at Truelove Lowland, Devon Island, N.W.T. Acetylene reduction rates of soil–plant cores from a variety of plant communities were measured under uniform conditions of light and temperature during the 1987 and 1988 growing seasons. Concurrent measurements of soil moisture and extractable nitrogen and phosphorus were also made. Effects of temperature, moisture, and phosphorus were examined in manipulative experiments. Acetylene reduction rates were highest in brackish environments, intermediate in mesic to hydric terrestrial and in aquatic communities, and lowest on xeric beach ridges. Rates generally increased during early season, then decreased through mid to late season. Among the three parameters examined, rates were most highly correlated to soil moisture. The temperature optimum for fixation was near 20 °C. There was a strong, but reversable, depression in acetylene reduction in response to experimental desiccation, and weekly phosphorus fertilization had a strong positive effect on fixation rates. The highest fixation rates along the marine shoreline were associated with high phosphorus input from marine algae and greater biomass of cyanobacteria. Because of the overriding importance of moisture, changes in nitrogen and phosphorus levels accompanying ecosystem development do not appear to strongly control nitrogen fixation in terrestrial, nonbrackish sites in this polar desert oasis. Key words: nitrogen fixation, environmental regulation, Devon Island, High Arctic, Nostoc commune, cyanobacteria.

Conversion factor between acetylene reduction and nitrogen fixation in free-living cyanobacteria from high arctic habitats

1999 ◽  
Vol 45 (3) ◽  
pp. 223-229 ◽  
Author(s):  
Turid Liengen
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Conversion Factor ◽  
Soil Surface ◽  
High Arctic ◽  
Acetylene Reduction Activity ◽  
Nostoc Commune ◽  
Free Living ◽  
Conversion Factors ◽  
N Incorporation

The conversion factor between acetylene reduction and15N incorporation in free-living cyanobacteria was determined in different high arctic habitats in the area of Ny-Ålesund (78.5°N, 11.6°E), Spitsbergen, in the summer of 1994. The experiments were carried out under constant conditions, 19°C and 200 µE·m-2·s-1. The nitrogen-fixation activities, measured as15N-incorporation, were in the range 4.01-6.54 mg N2fixed·gdw-1·day-1(dw, dry weight) in sheets of Nostoc commune and 778-1206 mg N2fixed·m-2·day-1in the cyanobacterial crusts. The acetylene reduction activities were in the range 0.72-1.91 mg ethylene produced·gdw-1·day-1of N. commune and 12.8-63.7 mg ethylene produced·m-2·day-1in the cyanobacterial crusts. The conversion factor of N. commune ranged from 0.11 to 0.48 for ethylene produced to nitrogen fixed, whereas the cyanobacterial crusts covering the soil surface gave conversion factors in the range 0.022-0.073 for ethylene produced to nitrogen fixed. An Anabaena sp., isolated from one of the habitats investigated, gave conversion factors near the theoretical factor of 4, when determined at 14.0 and 17.3°C. It was concluded that the acetylene reduction activity of free-living cyanobacteria in high arctic habitats results in underestimates of the real nitrogen-fixation activity in these environments.Key words: nitrogen fixation, acetylene reduction, conversion factor, cyanobacteria, Nostoc commune, high arctic.

Comparisons of nitrogen fixation estimates in soybeans by nodule weight, leghemoglobin content, and acetylene reduction

1973 ◽  
Vol 19 (9) ◽  
pp. 1165-1168 ◽  
Author(s):  
H. S. Johnson ◽  
D. J. Hume
Keyword(s):  
Nitrogen Fixation ◽  
Glycine Max ◽  
Acetylene Reduction ◽  
Growth Period ◽  
Growing Season ◽  
Field Conditions ◽  
Soybean Cultivar ◽  
Fresh Weight ◽  
Stages Of Development ◽  
Glycine Max L

Nodule leghemoglobin content, acetylene reduction rates, and nodule weight determinations were made during an entire growth period of soybean (Glycine max (L.) Merr. cv. Altona) plants grown under field conditions. High correlations within most sampling dates were found between each pair of possible comparisons of these indicators of nitrogen fixation.Rates of conversion of acetylene to ethylene per milligram leghemoglobin constantly decreased during the growing season, whereas leghemoglobin content per gram nodule fresh weight remained relatively constant. These results indicate that leghemoglobin content of nodules could be used to compare rates of nitrogen fixation in plants of a soybean cultivar at similar stages of development but should not be used to compare fixation rates in plants at different stages in ontogeny.

Ecosystem scale evidence for the contribution of vanadium-based nitrogenase to biological nitrogen fixation

2020 ◽  
Author(s):  
Jean-Philippe Bellenger ◽  
Romain Darnajoux ◽  
Nicolas Magain ◽  
Marie Renaudin ◽  
Francois Lutzoni ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
High Latitude ◽  
Biological Nitrogen Fixation ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
The Arctic ◽  
Field Evidence ◽  
N Input ◽  
Vanadium Nitrogenase ◽  
Biological Nitrogen

<p>Nitrogen is the primary limiting nutrient in high latitude ecosystems. Biological nitrogen fixation (BNF) by microorganisms associated with cryptogamic covers, such as cyanolichens and bryophytes, is an important source of new reactive nitrogen in pristine, high-latitude ecosystems. BNF is catalyzed by the enzyme nitrogenase, for which three isoforms have been described; the canonical molybdenum (Mo) nitrogenase which requires Mo in its active site and two alternative nitrogenases, the vanadium and iron-only nitrogenases. The low availability of Mo on land has been shown to limit BNF in many ecosystems from the tropical forest to the arctic tundra. Alternative nitrogenases have been suggested as viable alternatives to cope with Mo limitation of BNF, however, field data supporting this long-standing hypothesis have been lacking.</p><p>Here, we elucidated the contribution of the vanadium nitrogenase to BNF by cyanolichens across a 600 km latitudinal transect in eastern Canadian boreal forests. We report a widespread activity of the vanadium nitrogenase which contributed between 15 to 50% of total BNF rates on all sites. Vanadium nitrogenase contribution to BNF was more robust in the northern part of the transect. Vanadium nitrogenase contribution to BNF also changed during the growing season, with a three-fold increase between the early (May) and late (September) growing season. By including the contribution of the vanadium nitrogenase to BNF, estimates of new N input by cyanolichens increase by up to 30%, a significant change in these low N input ecosystems. Finally, we found that Mo availability was the primary driver for the contribution of the vanadium nitrogenase to BNF with a Mo threshold of ~ 250 ng.g<sub>lichen</sub><sup>-1</sup> for the onset of vanadium based BNF.</p><p>This study on N<sub>2</sub>-fixing cyanolichens provides extensive field evidence, at an ecosystem scale, that vanadium-based nitrogenase greatly contributes to BNF when Mo availability is limited. The results showcase the resilience of BNF to micronutrient limitation and reveal a strong link between the biogeochemical cycle of macro- and micronutrients in terrestrial ecosystems. Given widespread findings of Mo limitation of BNF in terrestrial ecosystems, additional consideration of vanadium-based BNF is required in experimental and modeling studies of terrestrial biogeochemistry.</p>

Nitrogen fixation in soils of Truelove Lowland, Devon Island, Northwest Territories

1975 ◽  
Vol 53 (14) ◽  
pp. 1387-1399 ◽  
Author(s):  
R. C. Stutz ◽  
L. C. Bliss
Keyword(s):  
Nitrogen Fixation ◽  
Vascular Plants ◽  
Beach Ridge ◽  
Nostoc Commune ◽  
Cushion Plants ◽  
Devon Island ◽  
Reduction Assay ◽  
Sedge Meadows ◽  
Incubation Temperatures ◽  
Biological Nitrogen

Biological nitrogen fixation was studied on Truelove Lowland, Devon Island, N. W. T., in three different habitats. Raised beach ridges, resulting from postglacial uplift, form well-defined xeric habitats, which are dominated by dwarf shrubs and cushion plants. Hummocky sedge meadows with associated mosses and forbs comprise the second intensively studied habitat. Waterlogged wet sedge meadows with moss were studied less intensively.Nitrogen fixation was estimated using acetylene-reduction assay. Incubation temperatures were moderated by burying the jars in soil pits (10 cm) on site.Available nitrogen was determined by microkjeldahl analysis of KCl soil extracts.Symbiotic nitrogen fixation by vascular plants is nil on Truelove Lowland. One lichen species, Peltigera aphthosa, reduced acetylene (5.1 μμmol∙mg−1∙h−1). Nostoc commune, a prominent blue-green alga on meadow soils, reduced acetylene at a rate 10 times that of P. aphthosa. An estimated 30 and 7 mg N∙m−2∙year−1 was fixed by bacteria and soil algae in beach ridge soil in 1971 and 1972 respectively, and 380 and 120 mg N∙m−2∙year−1 was fixed in meadow soils in the same years.

Nitrogen fixation in the high arctic tundra at Sarcpa Lake, Northwest Territories

1985 ◽  
Vol 63 (5) ◽  
pp. 974-979 ◽  
Author(s):  
Jim D. Karagatzides ◽  
Martin C. Lewis ◽  
Herbert M. Schulman
Keyword(s):  
Nitrogen Fixation ◽  
Northwest Territories ◽  
Acetylene Reduction ◽  
Biological Nitrogen Fixation ◽  
Arctic Tundra ◽  
High Arctic ◽  
Fixed Nitrogen ◽  
Free Living ◽  
Blue Green Algae ◽  
Biological Nitrogen

The acetylene reduction assay was used to examine biological nitrogen fixation in the high arctic tundra at Sarcpa Lake, Northwest Territories (68°32′ N, 83°19′ W). The highest rates of acetylene reduction (9.37 ± 3.19 μmol C2H4 m−2 h−1) were in habitats that had a high density of the legumes Oxytropis maydelliana, O. arctobia, and Astragalus alpinus. Nitrogen fixation in the wet soils along the shore of a small lake was similar (8.87 ± 4.35 μmol C2H4 m−2 h−1) because of the blue-green alga Nostoc, which associates with mosses. Free-living blue-green algae and lichens made insignificant contributions to the total nitrogen fixation budget because they were uncommon and fixed nitrogen at a slower rate. Nitrogen-fixing lichens in the area included Stereocaulon arenarium and S. rivulorum. It is concluded that legumes have a significant input to the biological nitrogen fixation budget at Sarcpa Lake.

Seasonal and site-specific variations in nitrogen fixation in a high arctic area, Ny-Ålesund, Spitsbergen

1997 ◽  
Vol 43 (8) ◽  
pp. 759-769 ◽  
Author(s):  
Turid Liengen ◽  
Rolf Arnt Olsen
Keyword(s):  
Nitrogen Fixation ◽  
C:N Ratio ◽  
High Arctic ◽  
Rapid Decline ◽  
Soil Cores ◽  
Nostoc Commune ◽  
In Situ Conditions ◽  
Intact Soil Cores ◽  
Intact Soil

Nitrogen fixation was measured in different habitats in the area of Ny-Ålesund, Spitsbergen, using the acetylene reduction method on intact soil cores and Nostoc commune growing in macroscopic sheet communities. The samples were incubated both under constant conditions (19 °C and 200 μE∙m−2∙s−1) and under in situ conditions. Cyanobacteria were considered to be the major nitrogen-fixing organisms. The nitrogen fixation rates showed a seasonal variation during the growing season of 1994, with low activities just after the snow melt, increasing until the middle of August and showing a rapid decline after the snow fell on August 29. The soil temperature at the time of sampling showed a positive, linear correlation with the nitrogen fixation activities measured on intact soil cores, whereas the nitrogen fixation activities measured in situ of N. commune showed a positive, linear dependence on the moisture content in the sheets and the incubation temperatures inside the incubation vessels during the experiments. The optimal temperature of the nitrogen fixation activity was about 20 °C, both for N. commune and a Puccinellia salt marsh. The highest nitrogen fixation rate measured in situ was at a patterned ground, which had the highest pH, the highest concentrations of extractable calcium and magnesium, and the highest C:N ratio measured.Key words: nitrogen fixation, cyanobacteria, Nostoc commune, high arctic.

The temperature dependence of thallus nitrogenase activity in Peltigera canina

1975 ◽  
Vol 53 (6) ◽  
pp. 527-529 ◽  
Author(s):  
E. Maikawa ◽  
K. A. Kershaw
Keyword(s):  
Nitrogen Fixation ◽  
Temperature Dependence ◽  
Soil Nitrogen ◽  
Acetylene Reduction ◽  
Reduction Method ◽  
Nitrogenase Activity ◽  
Low Levels ◽  
Peltigera Canina

Comparative rates of nitrogen fixation in the lichen Peltigera canina from subarctic and temperate habitats have been examined using the acetylene reduction method. Maximum acetylene reduction at thallus saturation and with 20000 lx illumination takes place at 16 °C in subarctic material and at 21 °C in temperate material. This adaptation of nitrogenase activity to temperature in P. canina is discussed in relation to low levels of soil nitrogen in arctic systems.

Environmental factors influencing the nitrogen fixation activity of free-living terrestrial cyanobacteria from a high arctic area, Spitsbergen

1999 ◽  
Vol 45 (7) ◽  
pp. 573-581 ◽  
Author(s):  
Turid Liengen
Keyword(s):  
Nitrogen Fixation ◽  
High Arctic ◽  
Nostoc Commune ◽  
Free Living ◽  
Terrestrial Cyanobacteria ◽  
Nitrogen Fixation Activity ◽  
Fixation Activity ◽  
Field Samples ◽  
Anabaena Sp ◽  
Arctic Area

The influence of environmental factors on the nitrogen fixation activity of free-living, terrestrial cyanobacteria from a high arctic area were investigated using experimental manipulations with two different types of field samples, including macroscopic sheets of Nostoc commune and soil samples with a cyanobacterial crust from a Puccinellia salt marsh. In addition, a cultured Anabaena sp. previously isolated from the salt marsh was examined. Nitrogen fixation activity was measured using the acetylene reduction method. The nitrogen fixation mainly took place in the light, but even after 12 h incubation in darkness, low activities were maintained. Phosphorus fertilization stimulated the nitrogen fixation activity, and the highest activities were obtained with about 300 μM phosphate, both in the field samples and the cultured Anabaena sp. Ammonium (28 mM) immediately inhibited the nitrogen fixation activity of the cultured Anabaena sp, whereas 14 mM urea and 540 μM glutamate led to a weaker and slower inhibition of the nitrogen fixation activity, showing that the cultured Anabaena sp. was able to assimilate these combined nitrogen sources. Nitrate did not have any inhibitory effect on nitrogen fixation activity, either in the field samples or in the cultured Anabaena sp. Both the field samples and the cultured Anabaena sp. showed tolerance against sodium chloride concentrations corresponding to the concentration in seawater. The temperature optimum of the nitrogen fixation activity of the cultured Anabaena sp. was about 20°C. Key words: nitrogen fixation, cyanobacteria, Nostoc commune, Anabaena sp., high arctic.

A new nitrogen-fixing Clostridium species from a high Arctic ecosystem

1979 ◽  
Vol 25 (8) ◽  
pp. 947-948 ◽  
Author(s):  
D. C. Jordan ◽  
Patricia J. McNicol
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
High Arctic ◽  
Undescribed Species ◽  
Nitrogen Fixing ◽  
Canadian High Arctic ◽  
Clostridium Species ◽  
Gram Negative ◽  
Arctic Ecosystem ◽  
Devon Island

A hitherto undescribed species of yellow-pigmented, Gram-negative Clostridium sp., possessing nitrogenase activity, has been isolated from a number of sampling sites on the Truelove Lowland of Devon Island in the Canadian high Arctic. This bacterium, tentatively designated Clostridium arcticum sp. nov., accounted for 19% of all isolates recovered which were capable of anaerobic nitrogen fixation.

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