Nitrogen fixation and methane metabolism in a stream sediment–water system amended with leaf material

1981 ◽  
Vol 27 (5) ◽  
pp. 511-516 ◽  
Author(s):  
T.-Y. Tam ◽  
C. I. Mayfield ◽  
W. E. Inniss
Keyword(s):  
Methane Production ◽  
Acetylene Reduction ◽  
Reduction Rate ◽  
Water System ◽  
Stream Sediment ◽  
Leaf Material ◽  
Oxidation Of Methane ◽  
Acetylene Reduction Rate ◽  
Low Levels ◽  
Methane Metabolism

The reduction of acetylene and the production and oxidation of methane in a stream sediment–water system amended with either fresh leaves or autumn-shed leaves in the presence and absence of air were studied. Net methane production by the sediment–water system occurred only when leaf material was added, with fresh leaves giving 2.2 times the methane accumulation as autumn-shed leaves. Static incubation in the presence of air had little effect on net methane production, with such production being about the same as (with fresh leaves) or 79% of (with autumn-shed leaves) the anaerobic rates. Acetylene reduction was more affected by the presence of air, with anaerobic rates being at very low levels. The presence of fresh leaves was again stimulatory, with the acetylene reduction rate being 5.5-fold greater than that occurring with autumn-shed leaves.

Lichenized unicellular cyanobacteria fix nitrogen in the light

2007 ◽  
Vol 85 (10) ◽  
pp. 1003-1006 ◽  
Author(s):  
P. D. Crittenden ◽  
X. Llimona ◽  
L. G. Sancho
Keyword(s):  
Diurnal Variation ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Reduction Rate ◽  
Carbon Flow ◽  
Diurnal Pattern ◽  
Fungal Symbiont ◽  
Minimum Rate ◽  
Isothermal Conditions ◽  
Acetylene Reduction Rate

Diurnal variation in N2-fixation (acetylene reduction) rate was measured in Thyrea girardii (Durieu & Mont.) Bagl. & Carestia and Thyrea confusa Henssen, lichens containing a unicellular cyanobacterial photobiont. In field assays, mean acetylene-reduction rates in the light were 25.8 ± 8.9 (n = 11) and 21.0 ± 5.6 nmol C2H4·g–1·h–1 (n = 13) for T. girardii and T. confusa, respectively, and the respective mean rates in the dark were 8.2 ± 1.8 (n = 26) and 13.5 ± 5.4 (n = 8) nmol C2H4·g–1·h–1. In laboratory assays under relatively isothermal conditions (ca. 19–22 °C), the maximum acetylene reduction rate (52.0 ± 6.0 nmol C2H4·g–1·h–1) was recorded in the light and the minimum rate (20.2 ± 6.0 nmol C2H4·g–1·h–1) in the dark. This diurnal pattern is contrary to expectations for unicellular cyanobacteria. We suggest carbon flow to the fungal symbiont reduces the potential for nitrogenase activity in the dark.

Nitrogen fixation associated with Scirpus atrovirens and other nonnodulated plants in Massachusetts

1978 ◽  
Vol 56 (21) ◽  
pp. 2636-2640 ◽  
Author(s):  
Todd M. Kana ◽  
John D. Tjepkema
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Reduction Rate ◽  
Herbaceous Plant ◽  
Soil Incubation ◽  
Old Field ◽  
Fourfold Increase ◽  
Constant Rate ◽  
Moderate Rate ◽  
Acetylene Reduction Rate

Nitrogen fixation was measured using the acetylene reduction technique in soil cores of 13 nonnodulated, herbaceous plant species growing in mesic and wetland habitats. Six species that grew in a well-drained portion of an old field exhibited low rates of N2 fixation (7 g N∙ha−1∙day−1). A bulrush, Scirpus atrovirens, which grew in an area of compacted soil in the old field, showed a moderate rate of N2 fixation (30–100 g N∙ha−1∙day−1). These old field species exhibited a lag of only a few hours before a constant rate of acetylene reduction occurred. The estimated rates for the six wetland species were generally higher, and there was a lag such that the activity was still increasing after 20 h of incubation. N2 fixation in cores of S. atrovirens was primarily associated with the roots and adhering soil. Incubation of the cores in N2 for 24 h caused a fourfold increase in the acetylene reduction rate over that in air, although the rates during the first 4 h were similar.

Nodule biomass and acetylene reduction rates of red alder and Sitka alder on Vancouver Island, B.C.

1981 ◽  
Vol 11 (2) ◽  
pp. 282-287 ◽  
Author(s):  
Dan Binkley
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Reduction Rate ◽  
Vancouver Island ◽  
Fixation Rate ◽  
Red Alder ◽  
Nodule Biomass ◽  
Closed Canopy ◽  
Management Alternative ◽  
Acetylene Reduction Rate

Three comparisons examined acetylene reduction rate and nodule biomass of red alder (Alnusrubra Bong.) and Sitka alder (Alnussinuata (Regel) Rydb.) on Vancouver Island, British Columbia. The first showed that the acetylene reduction rates of Sitka alder on four sites in early July 1979 varied from 8.8 to 22.0 μmol C2H2•g−1 dry nodule per hour; smaller nodules had the higher rates. In the second comparison, red alder and Sitka alder acetylene reduction rates for young plants were similar when assayed on the same day on the same site. Finally, acetylene reduction rates and nodule biomass were determined for both species growing in closed canopy stands on adjacent sites. In this pair of 20-year-old stands, red alder had double the acetylene reduction rate and three times the nodule biomass of the Sitka alder. Combining the nodule biomass estimates with the seasonal average reduction rates yielded current annual nitrogen fixation estimates (using C2H2) of 130 kg•ha−1•year−1 for the red alder plot and 20 kg•ha−1•year−1 for the Sitka alder plot. These estimates are within published ranges for the species. The lower fixation rate of Sitka alder is still substantial, relative to the nitrogen demands of conifers, and its shrub-like growth form makes it an attractive management alternative to red alder for biological nitrogen fixation in mixed conifer–alder plantations.

Identification of North American soybean lines that form nitrogen-fixing nodules with Rhizobium fredii USDA257

1992 ◽  
Vol 72 (1) ◽  
pp. 49-55 ◽  
Author(s):  
P. A. Balatti ◽  
S. G. Pueppke
Keyword(s):  
United States ◽  
North American ◽  
Acetylene Reduction ◽  
Reduction Rate ◽  
Nitrogen Fixing ◽  
Maturity Group ◽  
Midwestern United States ◽  
Rhizobium Fredii ◽  
Acetylene Reduction Rate

Rhizobium fredii produces nitrogen-fixing (Fix+) nodules on primitive soybean lines, but most strains do not form such structures with the small number of agronomically advanced lines that have been tested. We systematically evaluated the ability of R. fredii USDA257 to produce Fix+ nodules on 197 soybean lines available in the midwestern United States. Thirty-four of 197 such lines were Fix+. The frequency of this response was positively correlated with increasing maturity group. The acetylene-reduction rate of one advanced cultivar, Davis, was greater than that of the primitive cultivar, Peking. Our data indicate that the capacity to nodulate effectively with USDA257 is widespread in contemporary North American soybean lines.Key words: Acetylene-reduction, nodulation, Rhizobium, soybean

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.

scholarly journals Genetic Analysis of the Methanol- and Methylamine-Specific Methyltransferase 2 Genes of Methanosarcina acetivorans C2A

2008 ◽  
Vol 190 (11) ◽  
pp. 4017-4026 ◽  
Author(s):  
Arpita Bose ◽  
Matthew A. Pritchett ◽  
William W. Metcalf
Keyword(s):  
Genetic Analysis ◽  
Methane Production ◽  
Untranslated Region ◽  
Gene Fusions ◽  
Methanosarcina Acetivorans ◽  
Concerted Effort ◽  
Genes Encoding ◽  
Low Levels ◽  
Reduced Rate

ABSTRACT The entry of methanol into the methylotrophic pathway of methanogenesis is mediated by the concerted effort of two methyltransferases, namely, methyltransferase 1 (MT1) and methyltransferase 2 (MT2). The mtaA1, mtaA2, and mtbA genes of Methanosarcina acetivorans C2A encode putative methanol- or methylamine-specific MT2 enzymes. To address the in vivo roles of these genes in growth and methanogenesis from known substrates, we constructed and characterized mutants with deletions of each of these genes. The mtaA1 gene is required for growth on methanol, whereas mtaA2 was dispensable. However, the mtaA2 mutant had a reduced rate of methane production from methanol. Surprisingly, deletion of mtaA1 in combination with deletions of the genes encoding three methanol-specific MT1 isozymes led to lack of growth on acetate, suggesting that MT1 and MT2 enzymes might play an important role during growth on this substrate. The mtbA gene was required for dimethylamine and monomethylamine (MMA) utilization and was important, but not required, for trimethylamine utilization. Analysis of reporter gene fusions revealed that both mtaA1 and mtbA were expressed on all methanogenic substrates tested. However, mtaA1 expression was induced on methanol, while mtbA expression was down-regulated on MMA and acetate. mtaA2 was expressed at very low levels on all substrates. The mtaA1 transcript had a large 5′ untranslated region (UTR) (275 bp), while the 5′ UTR of the mtbA transcript was only 28 bp long.

Sign in / Sign up

Export Citation Format

Share Document