Seasonal variation in nitrogen fixation, associated microbial populations, and carbohydrates in roots and rhizomes of Typha latifolia (Typhaceae)

1984 ◽  
Vol 62 (9) ◽  
pp. 1965-1967 ◽  
Author(s):  
David D. Biesboer
Keyword(s):  
Nitrogen Fixation ◽  
Nitrogenase Activity ◽  
Anaerobic Bacteria ◽  
Typha Latifolia ◽  
Root Surface ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Free Sugar ◽  
Fixation Rate ◽  
Reduction Assay

Seasonal changes in nitrogen fixation, numbers of nitrogen-fixing bacteria associated with the roots, and rhizome–root carbohydrates were studied for the broad-leaved cattail, Typha latifolia L. Populations of anaerobic and aerobic diazotrophic bacteria were present on the root surface. Anaerobic bacteria predominated in the diazotrophic association, were more active in the acetylene reduction assay, and generally outnumbered aerobic bacteria by 2 to 1 during maximum rates of seasonal nitrogen fixation. The observed maximum nitrogen fixation rate coincided closely with reproductive development in Typha and peak microbial populations. Starch levels in rhizomes were nearly depleted during the middle of the growing season, whereas free sugar concentrations remained stable. Sugar concentrations in the roots increased rapidly during rhizome–root growth and decreased rapidly prior to peak nitrogenase activity.

para-Hydroxybenzoate supported nitrogen fixation in Azotobacter vinelandii strain OP (13705)

1988 ◽  
Vol 34 (11) ◽  
pp. 1271-1275 ◽  
Author(s):  
Jay B. Peterson ◽  
Lynn S. Peterson
Keyword(s):  
Nitrogen Fixation ◽  
Cytoplasmic Membrane ◽  
Azotobacter Vinelandii ◽  
Nitrogenase Activity ◽  
Molecular Nitrogen ◽  
Carbon Sources ◽  
Gel Filtration ◽  
Cell Extracts ◽  
Reduction Assay ◽  
Membrane Bound

Azotobacter vinelandii cells grew with molecular nitrogen and p-hydroxybenzoate as the sole added nitrogen and carbon sources. Nitrogenase activity in p-hydroxybenzoate grown cells was demonstrated with the acetylene reduction assay. Cell extracts contained the enzymes p-hydroxybenzoate hydroxylase (EC 1.14.13.2) and protocatechuate 3,4-dioxygenase (EC 1.13.1.3); oxygenases associated with p-hydroxybenzoate metabolism. These enzymes separated from respiration particles with gel filtration chromatography, indicating that they are soluble and not membrane bound. This evidence indicates that oxygen enters to the inner face of the cytoplasmic membrane during nitrogen fixation.

Rhodolith holobionts are not sources of fixed nitrogen in a northeastern Gulf of Mexico patch reef

2020 ◽  
Author(s):  
Ethan C Cissell ◽  
Sven A Kranz ◽  
Sophie J McCoy
Keyword(s):  
Nitrogen Fixation ◽  
Gulf Of Mexico ◽  
Nitrogenase Activity ◽  
Patch Reef ◽  
Dry Mass ◽  
Fixation Rate ◽  
Northeastern Gulf Of Mexico ◽  
Local Ecosystem ◽  
Water Column Nutrient ◽  
Functional Analyses

Rhodoliths provide numerous benefits to coastal ecosystems and help support high biodiversity. No study, however, has explored rhodoliths that occupy northeastern Gulf of Mexico patch reefs, and their contributions to local ecosystem function remain uncharacterized. Here, we employed the acetylene reduction assay to assess nitrogen fixation capability in rhodolith holobionts (Lithothamnion spp.; Rhodophyta), sediment, and surrounding seawater from a subtropical patch reef ecosystem in the northeastern Gulf of Mexico. We found no evidence for nitrogenase activity in rhodolith holobionts or seawater from our study site, while nitrogenase activity in sediment underlying rhodoliths was approximately equivalent to a nitrogen fixation rate of 0.521 (SD 0.087) nmol N2 g dry mass−1 hr−1. Our results suggest that rhodoliths in the northeastern Gulf of Mexico rely on sources of nitrogen from sediment nitrogen fixation or water column nutrient availability rather than the activity of symbiotic diazotrophic microorganisms. Functional analyses recognizing rhodoliths as holobionts warrant further investigation to better understand the ecology of rhodoliths.

Ecological aspects of nitrogen fixation (acetylene reduction) associated with plants of a Minnesota wetland community

1988 ◽  
Vol 66 (7) ◽  
pp. 1359-1363 ◽  
Author(s):  
Nancy A. Eckardt ◽  
David D. Biesboer
Keyword(s):  
Nitrogen Fixation ◽  
Acetylene Reduction ◽  
Lemna Minor ◽  
Nitrogenase Activity ◽  
Typha Latifolia ◽  
Early Summer ◽  
Acetylene Reduction Activity ◽  
Redox Potentials ◽  
Carex Stricta ◽  
Calamagrostis Canadensis

Nitrogen fixation in association with four plant species of a Minnesota wetland, Typha latifolia L., Carex stricta Lam., Calamagrostis canadensis (Michx.) Beauv., and Lemna minor L., was estimated using the acetylene-reduction technique on soil – root cores. The estimated rates of nitrogen fixation (acetylene reduction) for plants growing in submerged soils, in kilograms per hectare per year, are T. latifolia, 0.91; Carex stricta, 0.47; Calamagrostis canadensis, 0.24; and L. minor, 1.90. Significantly higher fixation rates were found with plants growing in submerged areas than with those on the well-drained shore. These differences could not be correlated with differences in levels of extractable ammonium and nitrate in the substrate and were attributed to low redox potentials favoring nitrogenase activity in submerged areas. The seasonal trend in acetylene reduction activity appeared to be correlated with the reproductive stages of Typha, Carex, and Calamagrostis. Maximum acetylene reduction for these species was observed just after flower maturation, in early summer for Carex and Calamagrostis and late summer for Typha, suggesting that nitrogen fixation may be an important source of nitrogen in developing seeds. Overall, nitrogen fixation was estimated to supply as much as 11 kg N∙ha−1∙year−1 to this wetland community.

Nitrogen fixation associated with grasses in Oregon

1976 ◽  
Vol 22 (4) ◽  
pp. 523-530 ◽  
Author(s):  
Arthur D. Nelson ◽  
Lynn E. Barber ◽  
John Tjepkema ◽  
Sterling A. Russell ◽  
Robert Powelson ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Aerobic Bacteria ◽  
Bacillus Species ◽  
Natural Conditions ◽  
Wheat Roots ◽  
Natural Grasslands ◽  
Reduction Assay ◽  
Reducing Activity ◽  
Acetylene Reducing Activity ◽  
Root Surfaces

Nitrogen fixation associated with both natural grasslands and grain crops of Oregon was studied using the acetylene-reduction assay. A number of the grasses collected had some acetylene-reducing activity. Agrostis tenuis Sibth. had substantially greater activity than any of the other species, with a mean rate estimated at 37 g N2 fixed per hectare per day. Assuming 100 days of activity, about 3 kg of N2 would be fixed per hectare per year. This quantity of nitrogen may be important in the maintenance of this species under natural conditions. Nitrogen-fixing microorganisms were isolated from the root surfaces of some of the grasses. Cultures of Bacillus macerans, Bacillus polymyxa, and Enterobacter cloacae were isolated from wheat roots as were two cultures which have not been assigned a specific taxonomic classification. Strains of N2-fixing Bacillus species and Gram-negative aerobic bacteria were isolated from Festuca and Agrostis.

The acetylene reduction assay for measuring nitrogen fixation in waterlogged soil

1971 ◽  
Vol 17 (8) ◽  
pp. 1049-1056 ◽  
Author(s):  
W. A. Rice ◽  
E. A. Paul
Keyword(s):  
Nitrogen Fixation ◽  
Aqueous Phase ◽  
Nitrogenase Activity ◽  
Total Sample ◽  
Gas Diffusion ◽  
N Fixation ◽  
Waterlogged Soil ◽  
Sample Depth ◽  
Reduction Assay ◽  
Glucose System

Nitrogen fixation in waterlogged, soil–straw, and sand–clay–straw mixtures was measured with the C2H2 reduction assay, the 15N-tracer technique, and the Kjeldahl method. The reduction of 6 to 15 moles C2H2 corresponded to the fixation of 1 mole N2. The theoretical ratio is 3 moles C2H2 to 1 mole N2. A ratio of 3 moles C2H2 reduced for each mole of N2 fixed was obtained when samples of sand–clay–straw were incubated under conditions that minimized effects that were due to gas diffusion through the aqueous phase. Calculations indicated that N2 at a partial pressure of 0.2 atm above the samples was not sufficient to saturate the nitrogenase enzyme of the organisms in lower layers of soil–straw samples. Thus the concentration of N2 dissolved in the aqueous phase limited nitrogen fixation. C2H2 is more soluble in water than N2; the C2H2 reduction was not as limited by the C2H2 concentration in the aqueous phase.N2 was experimentally shown to be limited at depth in a sand–clay–glucose system in that fixation decreased from 128 to 36 μg N/g of sand–clay incubated so that the total sample depth ranged from 0.2 to 3 cm.The C2H2 reduction assay provides a method for measuring the potential nitrogenase activity in the waterlogged soil amended with straw; however, this assay must be calibrated for specific conditions. The data also indicate that where N2 diffusion rates may limit N fixation, a normal atmosphere (80%) of N2 should be used in the experiment.

UV Irradiation of Shell Eggs: Effect on Populations of Aerobes, Molds, and Inoculated Salmonella typhimurium

1997 ◽  
Vol 60 (6) ◽  
pp. 639-643 ◽  
Author(s):  
FUENG-LIN KUO ◽  
JOHN B. CAREY ◽  
STEVEN C. RICKE
Keyword(s):  
Salmonella Typhimurium ◽  
Uv Radiation ◽  
Uv Light ◽  
The Other ◽  
Uv Exposure ◽  
Microbial Populations ◽  
Aerobic Bacteria ◽  
Fluorescent Light ◽  
Uv Treatment ◽  
Shell Eggs

The effects were investigated of 254-nm UV radiation on populations of Salmonella typhimurium, aerobes, and molds on the shells of eggs. In the first experiment, the CFU of attached S. typhimurium cells on unwashed clean shell eggs were determined after 0, 1, 3, 5, and 7 min of UV treatment (620 μW/cm2) on both ends of the egg. All UV treatments significantly reduced S. typhimurium CFU (P < .01). UVtreatment (620 μW/cm2) in 1-min alternating light and dark cycles for 5 min (three light and two dark) was compared to 0, 3, and 5 min of UV treatment. No significant differences in microbial populations were observed among light and dark cycles and the other UV treatments. In a subsequent experiment, the same UV treatments were utilized to evaluate photoreactivation. After UV exposure, eggs were exposed to 1 h of fluorescent light or I h of darkness or cultured immediately. S. typhimurium CFU were significantly (P < .01) reduced by the UV treatments. However, no significant differences between microbial populations exposed to UV treatment and UV radiation plus photoreactivation were detected. For studies of aerobic bacteria and molds, different UV treatment times (0, 15, and 30 min) at the intensity of 620 μW/cm2 and different intensities (620, 1350, and 1720 μW/cm2) for 15 min were evaluated. Mold CFU per egg were either 0 or 1 for all UV treatments and a 99% reduction of CFU of aerobic bacteria per egg were observed for all UV treatments. It appears from these studies that UV light can significantly reduce populations of S. typhimurium, aerobes, and molds on shell eggs.

Studies on compatibility of nitrogen fixation by high-temperature-adapted Rhizobium strains and Vigna radiata genotypes at two moisture levels in calcareous soil

1983 ◽  
Vol 101 (2) ◽  
pp. 377-381 ◽  
Author(s):  
R. Rai ◽  
V. Prasad
Keyword(s):  
Nitrogen Fixation ◽  
High Temperature ◽  
Grain Yield ◽  
Vigna Radiata ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Summer Season ◽  
Green Gram ◽  
Rhizobium Strains

SUMMARYRhizobium strains adapted to high temperature, and genotypes of green gram, were used to study the symbiotic N2-fixation in a summer season at two moisture levels in calcareous soil. Different interactions between strains and genotypes were observedatthe two moisture levels. At both moisture levels, strain S4 with the green gram genotype S8 showed the greatest grain yield, nitrogenase activity, leghaemoglobin and ethanolsoluble carbohydrate of nodules.

Study of the role of Chlamydia, Mycoplasma, Ureaplasma and other microaerophilic and aerobic bacteria in uterine infections of mares with reproductive disorders

2003 ◽  
Vol 51 (1) ◽  
pp. 45-52 ◽  
Author(s):  
László Szeredi ◽  
M. Tenk ◽  
I. Schiller ◽  
Keyword(s):  
Pathogenic Bacteria ◽  
Anaerobic Bacteria ◽  
Aerobic Bacteria ◽  
Relative Importance ◽  
Reproductive Disorders ◽  
Taylorella Equigenitalis

In six healthy mares and 24 mares showing reproductive disorders swab samples were taken from the fossa clitoridis to isolate Taylorella equigenitalis, and from the uterus to isolate mycoplasmas, ureaplasmas and other aerobic bacteria. Swab samples were also taken from the uterus for Chlamydiaantigen ELISA and ChlamydiaPCR studies. The uterus of 27 mares was examined cytologically, and biopsy samples were taken from the endometrium for histological examinations and for immunohistochemical examinations aimed at the detection of chlamydiae. T. equigenitalis, mycoplasmas, ureaplasmas and chlamydiae could not be detected from any of the mares examined. Aerobic facultative pathogenic bacteria were isolated from mares with endometritis in four cases. In 18 out of 22 mares with endometritis (82%) no infective agents could be demonstrated. Further studies are needed to elucidate the relative importance of non-infectious causes of endometritis and of anaerobic bacteria often detectable in the uterus in the aetiology of the reproductive disorders observed.

High-temperature-adaptedAzospirillum brasilensestrains: growth and interaction response on associative nitrogen fixation, mineral uptake and yield of cheena (Panicum miliaceumL.) genotypes in calcareous soil

1988 ◽  
Vol 110 (2) ◽  
pp. 321-329 ◽  
Author(s):  
R. Rai
Keyword(s):  
Nitrogen Fixation ◽  
High Temperature ◽  
Calcareous Soil ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Cross Resistance ◽  
Mineral Uptake ◽  
Associative Nitrogen Fixation ◽  
Seed Inoculation ◽  
Resistance To Penicillin

SummaryHigh-temperature-adapted strains RAU 1, RAU 2 and RAU 3 ofAzospirillum brasilenseC 7 were isolated from stepwise transfer to higher temperature (30 to 42 °C). One of the strains (RAU 1) showed more growth, greater nitrogenase and hydrogenase activities at 30 and 42 °C than parental and other temperature-adapted strains. This strain also showed growth and more nitrogenase activity from pH 6·5 to 8·0. Strain RAU 1 showed cross-resistance to penicillin (300/µg/ml) but not to streptomycin, kanamycin, viomycin and polymixin B at 30 and 42 °C. It was demonstrated in field plots in calcareous soil that seed inoculation with RAU 1 enhanced mineral uptake of cheena. Inoculation with RAU 1 led to a significant increase in associative nitrogen fixation, dry weight of roots, grain and straw yield of cheena compared with the uninoculated control with or without applied N, but the effect of seed inoculation with high-temperature-adapted strains was variable with different genotypes of cheena.

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