Physiology of Nitrogen Fixation in Two New Strains of Anabaena

1985 ◽  
Vol 40 (5-6) ◽  
pp. 406-408 ◽  
Author(s):  
Pei-Chung Chen

Abstract Two different cyanobacteria, Anabaena CH 1 and CH2, were isolated from Taiwan paddy soils. Both strains can grow well with daily dilution method. Anabaena CH1 shows a blue-green color and Anabaena CH2 a green brownish one. Nitrogenase activity decreased as cultures were transferred from light to dark. When a darkened culture was placed again into the light, nitrogenase activity recovered within two hours, but not in the presence of chloramphenicol. Energy supply for nitrogenase within both strains was different. Nitrogenase activity of Anabaena CH1 was light-dependent and oxygen in heterocyst was exhausted through oxyhydrogen reaction. Except photosynthesis, respiration may be used as energy source for nitrogenase in Anabaena CH2. Respiration was the major one to protect nitrogenase against oxygen.

1986 ◽  
Vol 106 (2) ◽  
pp. 331-336 ◽  
Author(s):  
J. L. N. Rao ◽  
V. Bajaramamohan Rao

SUMMARYThe influence of addition of sulphate on acetylene reduction in three paddy soils differing in their properties under two water regimes was investigated in a laboratory experiment. Nitrogenase activity was high in a P-deficient alkaline soil and addition of sulphate further enhanced the activity under two water regimes, with a pronounced stimulation under non-flooded conditions. Sulphate application to submerged alluvial soil enhanced nitrogenase activity with no apparent effect under non-flooded conditions. In acid sulphate saline Pokkali soil sulphate addition had little effect on the nitrogenase activity. Sulphate addition did not result in significant changes in the soil pH and redox potential. No relationship seemed to exist between the sulphate disappearance and stimulation of nitrogenase in these soils. A differential stimulation of N2-fixing microorganisms was noticed as a result of sulphate application. Results suggest that sulphate-induced stimulation of nitrogenase activity occurs in non-flooded soils.


1983 ◽  
Vol 61 (11) ◽  
pp. 2774-2782 ◽  
Author(s):  
A. J. P. Burggraaf ◽  
W. A. Shipton

Several Frankia isolates were tested for their growth ability on a mineral medium containing glucose, succinic acid, or propionic acid as the sole carbon–energy source. Utilization of these nutrients allowed a preliminary discrimination between isolates. Propionic acid turned out to be a rather universal carbon source for the isolates involved in this study. In a system containing propionic acid as C–energy source and NH4Cl as N source, the development of infectivity on A. glutinosa with free-living cultures of CpI1 was followed during a growth period of 30 days. The growth pattern was compared with the development of both infective and viable units and the number of hyphal units and spores counted in mildly sonicated samples. On the same medium without NH4Cl several isolates were studied for the development of nitrogenase activity (acetylene reduction) in a growth experiment. The relation between growth and nitrogen fixation was also studied and compared in some experiments with the development of vesicles.


1983 ◽  
Vol 101 (2) ◽  
pp. 377-381 ◽  
Author(s):  
R. Rai ◽  
V. Prasad

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.


1988 ◽  
Vol 110 (2) ◽  
pp. 321-329 ◽  
Author(s):  
R. Rai

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.


1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman

Turfs of 'Park' Kentucky bluegrass reestablished in the greenhouse and inoculated with Klebsiella pneumoniae (W6) showed significantly increased nitrogen fixation (acetylene reduction) compared with control turfs. Mean ethylene production rates per pot were 368 nmol h−1 for K. pneumoniae treated turfs, 55 nmol h−1 for heat-killed K. pneumoniae treated turfs, and 44 nmol h−1 for untreated turfs. Calculated lag periods before activity was observed were generally very short (less than 1 h).When 'Park' Kentucky bluegrass was grown from seed on soil-less medium of Turface, a fired aggregate clay, inoculation with K. pneumoniae (W6) resulted in 9 of 11 turfs showing nitrogenase activity (mean ethylene producion rate per pot was 195 nmol h−1). Only 3 of 11 turfs treated with heat-killed K. pneumoniae showed any activity and their mean rate of ethylene production (40 nmol h−1 per pot) was significantly lower than that for turfs treated with K. pneumoniae.Using the 'Park'–Turface soil-less model system it was shown that acetylene reducing activity was (i) root associated, (ii) generally highest at a depth of 1–4 cm below the surface, (iii) enhanced by washing excised roots, and (iv) inhibited by surface sterilization of excised roots. Klebsiella pneumoniae was recovered from Turface and roots showing acetylene reducing activity.


The International Biological Programme served as a focal point for studies on biological nitrogen fixation during the 1960s. The introduction of the acetylene reduction technique for measuring nitrogenase activity in the field led to estimates becoming available of the contribution of lichens, blue-green algae, nodulated non-legumes and bacterial-grass associations, as well as of legumes. Other studies carried out on the physiology and biochemistry of the process led to the eventual purification and characterization of the nitrogenase enzyme. These studies, collectively, provided the springboard for current work, so essential in view of the present energy crisis, on how to increase the use and efficiency of nitrogen-fixing plants, on the metabolic regulation of the nitrogenase enzyme and on the genetics of the nitrogen-fixing process, both in higher plants and in free-living micro-organisms.


2021 ◽  
Vol 10 (1) ◽  
pp. 28
Author(s):  
Isamu Maeda

Biological nitrogen fixation catalyzed by Mo-nitrogenase of symbiotic diazotrophs has attracted interest because its potential to supply plant-available nitrogen offers an alternative way of using chemical fertilizers for sustainable agriculture. Phototrophic purple nonsulfur bacteria (PNSB) diazotrophically grow under light anaerobic conditions and can be isolated from photic and microaerobic zones of rice fields. Therefore, PNSB as asymbiotic diazotrophs contribute to nitrogen fixation in rice fields. An attempt to measure nitrogen in the oxidized surface layer of paddy soil estimates that approximately 6–8 kg N/ha/year might be accumulated by phototrophic microorganisms. Species of PNSB possess one of or both alternative nitrogenases, V-nitrogenase and Fe-nitrogenase, which are found in asymbiotic diazotrophs, in addition to Mo-nitrogenase. The regulatory networks control nitrogenase activity in response to ammonium, molecular oxygen, and light irradiation. Laboratory and field studies have revealed effectiveness of PNSB inoculation to rice cultures on increases of nitrogen gain, plant growth, and/or grain yield. In this review, properties of the nitrogenase isozymes and regulation of nitrogenase activities in PNSB are described, and research challenges and potential of PNSB inoculation to rice cultures are discussed from a viewpoint of their applications as nitrogen biofertilizer.


2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Manabu Tobisa ◽  
Masataka Shimojo ◽  
Yasuhisa Masuda

We investigated the root distribution and nitrogen fixation activity of American jointvetch (Aeschynomene americanaL.) cv. Glenn, under waterlogging treatment. The plants were grown in pots under three different treatments: no waterlogging (control), 30 days of waterlogging (experiment 1), and 40 days of waterlogging (experiment 2). The plants were subjected to the treatments on day 14 after germination. Root dry matter (DM) weight distribution of waterlogged plants was shallower than controls after day 20 of waterlogging. Throughout the study period, the total root DM weight in waterlogged plants was similar to that in the controls. Enhanced rooting (adventitious roots) and nodule formation at the stem base were observed in waterlogged plants after day 20 of waterlogging. The average DM weight of individual nodules on the region of the stem between the soil surface and water surface of waterlogged plants was similar to that of individual taproot nodules in the controls. Waterlogged plants had slightly greater plant DM weight than the controls after 40 days of treatment. The total nitrogenase activity (TNA) of nodules and nodule DM weight were higher in waterlogged plants than in the controls. Waterlogged American jointvetch had roots with nodules both around the soil surface and in the area between the soil surface and water surface after 20 days of waterlogging, and they maintained high nitrogenase activity and net assimilation rate that resulted in an increased growth rate.


1971 ◽  
Vol 35 (1) ◽  
pp. 471-479 ◽  
Author(s):  
G. Rinaudo ◽  
J. Balandreau ◽  
Y. Dommergues

1988 ◽  
Vol 20 (1) ◽  
pp. 41-61 ◽  
Author(s):  
R. P. Fritz-Sheridan ◽  
D. S. Coxson

AbstractStereocaulon virgatum Ach. has colonized lava flows deposited on the west flank of the volcano La Soufrière. The mean annual rate of acetylene reduction was 43·4 nmol C2H4 gdw−1 h−1 with maximum rates during the prevalent cloud/shroud meteorology of 101 and minimum rates during rare high insolation events of 0·63 nmol gdw−1 h−1. Percentage thallus moisture was the major variable controlling nitrogenase activity. During cloud/shroud conditions the upper 90% of the lichen canopy reduced 85% of the acetylene. Canopy shading reduced intra-canopy temperatures allowing the basal 10% of the canopy to fix nitrogen during insolation shocks. Basal portions of pseudopodetia exhibited reduced rates of ethylene production when exposed to canopy surface light intensities during cloud/shroud conditions. The recovery pattern of nitrogenase following desiccation during an insolation shock is presented. Rates of photosynthesis during cloud/shroud conditions were high, reaching 50% of those attained during saturating light intensities.


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