Effect of nitrogen compounds on nitrogenase activity inHerbaspirillum seropedicaeSMR1

1997 ◽  
Vol 43 (9) ◽  
pp. 887-891 ◽  
Author(s):  
G. Klassen ◽  
F. O. Pedrosa ◽  
E. M. Souza ◽  
S. Funayama ◽  
L. U. Rigo
Keyword(s):  
Nitrogenase Activity ◽  
Nitrogen Sources ◽  
Transport Systems ◽  
Acetylene Reduction Activity ◽  
Nitrogen Compounds ◽  
Herbaspirillum Seropedicae ◽  
Reduction Activity ◽  
Charged Amino Acids ◽  
Tetramethylammonium Chloride ◽  
Methylammonium Chloride

The effect of nitrogen compounds on growth and nitrogenase activity of Herbaspirillum seropedicae SMR1 was determined. L-Glutamate or L-glutamine as sole nitrogen sources supported growth, and nitrogenase activity was observed only after exhaustion of L-glutamate or L-glutamine from the culture medium. L-Serine, L-alanine, or ammonium chloride supported growth but not acetylene reduction activity. No growth was observed with L-histidine, L-lysine, L-arginine, or with the amines methylammonium chloride, tetramethylammonium chloride, or ethylenediamine chloride. All the compounds promoted the switch off of nitrogenase activity except L-histidine, L-lysine, or L-arginine, which were not taken up. The results showed that H. seropedicae cannot utilize exogenously added L-histidine, L-arginine, L-lysine, methylammonium chloride, tetramethylammonium chloride, or ethylediamine as the sole N source for growth. The inability of the positively charged amino acids to promote nitrogenase switch off might be a result of the lack of transport systems and the eventual further metabolism of these compounds.Key words: Herbaspirillum seropedicae, nitrogenase inactivation, amino compounds uptake.

Nitrogenase Activity by Subterranean Clover and Other Temperate Pasture Legumes

1988 ◽  
Vol 15 (5) ◽  
pp. 657 ◽  
Author(s):  
AG Davey ◽  
RJ Simpson
Keyword(s):  
Root Respiration ◽  
Nitrogenase Activity ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Acetylene Reduction Activity ◽  
Diffusion Resistance ◽  
Pasture Legumes ◽  
Reduction Activity ◽  
Decline Rate ◽  
Nodulated Root

Nitrogenase (C2H2-reduction) activity and nodulated root respiration of intact plants of subterranean clover (Trifolium subterraneum L.) cv. Seaton Park nodulated by Rhizobium trifolii WU95 were measured in a flow-through system. Simultaneous declines in nitrogenase activity and respiration were exhibited 2 min after 10% C2H2 had been introduced into the gas stream. Declines in nitrogenase activity and nodulated root respiration provided an estimate of the efficiency of nitrogenase activity (mol CO2 evolved/mol C2H4 produced). The pre-decline rate of nitrogenase activity at time zero was thus calculated as the product of the respiration associated with nitrogenase activity and the reciprocal of the efficiency of nitrogenase activity. Pre-decline rates of nitrogenase activity were similar to peak rates for several pasture legumes. However, post-decline rates of activity were as much as 70% lower than the pre-decline rate. The age of subterranean clover plants had an important influence on the magnitude of the C2H2-induced decline; young plants exhibited the largest C2H2-induced inhibition of nitrogenase activity. Neither sainfoin (Onobrychis viciifolia Scop.) cv. Othello nodulated by Rhizobium sp. CC1108 nor yellow serradella (Ornithopus compressus L.) cv. Pitman nodulated by R. lupini WU425 exhibited C2H2-induced declines in nitrogenase activity. Nitrogenase-linked respiration of subterranean clover at the 14-leaf stage accounted for 50% of total nodulated root respiration. The oxygen diffusion resistance of the nodules increased in the presence of C2H2 but the effect was reversible once C2H2 was removed from the gas atmosphere. The pre-decline rate of acetylene reduction activity of subterranean clover reached a maximum at 10% C2H2. The C2H2-induced decline in nitrogenase activity was lower at subsaturating pC2H2 and was not detected at 0.4% C2H2.

A survey of angiosperms in Nova Scotia for rhizosphere nitrogenase (acetylene-reduction) activity

1978 ◽  
Vol 56 (18) ◽  
pp. 2218-2223 ◽  
Author(s):  
D. Smith ◽  
D. G. Patriquin
Keyword(s):  
Nova Scotia ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Reduction Technique ◽  
Acetylene Reduction Activity ◽  
Forage Grasses ◽  
Reduction Activity ◽  
Tropical Forage ◽  
Poorly Drained Soils

Excised root samples from 901 plants, representing 130 species of nonnodulated angiosperms largely in upland, pioneering habitats, were assayed for nitrogenase activity by the acetylene-reduction technique after overnight preincubation of the samples under low pO2. Most samples and most species exhibited very low excised root acetylene-reducing activities, but for 19 species, maximum values were greater than 50 nmol C2H4∙g−1∙h−1. In situ C2H2 assays, conducted on 10 species which had exhibited maximum excised root activities greater than 10 nmol C2H4∙g−1∙h−1, indicated average belowground N2-fixation rates of 3 to 92 g N∙ha−1∙day−1 and maxima greater than 100 g N∙ha−1∙day−1 for 3 of the 10 species. The highest values were for grasses characteristic of poorly drained soils and for some dicotyledonous weeds. It is concluded that the potential of temperate-zone angiosperms for nitrogenase activity by 'associative symbioses' approaches that of tropical forage grasses.

Temperature response of an associative N2-fixing Pseudomonas species in pure culture

1991 ◽  
Vol 37 (9) ◽  
pp. 715-718 ◽  
Author(s):  
Yiu-Kwok Chan
Keyword(s):  
Nitrogenase Activity ◽  
Temperature Response ◽  
Grass Species ◽  
Acetylene Reduction Activity ◽  
Optimum Growth Temperature ◽  
Reduction Activity ◽  
Key Words Nitrogen Fixation ◽  
Pseudomonas Species ◽  
Response To Temperature ◽  
Key Words Nitrogen

The growth rate and nitrogenase (acetylene reduction) activity of a pseudomonad isolated from the rhizosphere of the grass species Deschampsia caespitosa were investigated in the 0–35 °C temperature range. Growth was detected from 5 to 30 °C with or without provision of fixed N and its optimum growth temperature was about 25 °C, establishing its psychrotrophic response to temperature. Maximum nitrogenase activity was also found at about 25 °C. Low but significant nitrogenase activity was detected below 15 °C. This organism was confirmed to be a microaerobic diazotroph and it was sensitive to a dissolved O2 concentration of ca. 12 μM. It is probably dependent on the appropriate environment in the rhizosphere of the host plant in order to persist with sustained nitrogenase activity during cold and dormant periods. Key words: nitrogen fixation, Pseudomonas, psychrotroph, temperature.

Relative contributions to nitrogenase (acetylene reducing) activity of stem and root nodules in Sesbania rostrata

1992 ◽  
Vol 38 (6) ◽  
pp. 577-583 ◽  
Author(s):  
J. K. Ladha ◽  
Minviluz Garcia ◽  
R. P. Pareek ◽  
G. Rarivoson
Keyword(s):  
Acetylene Reduction ◽  
Root Nodule ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Dry Weight ◽  
Acetylene Reduction Activity ◽  
Sesbania Rostrata ◽  
Reduction Activity ◽  
Acetylene Reducing Activity ◽  
Aerial Stem

Six experiments, two each in the phytotron, greenhouse, and field, were conducted to assess the contribution of nitrogenase activity (acetylene reduction) by stem nodules in the presence and absence of root nodules of Sesbania rostrata (Brem & Oberm). In a greenhouse experiment, the effect of detaching already formed aerial stem nodules on the restoration of root nodules and nitrogenase activity was studied. The field experiment compared nodulation and acetylene-reduction activity by dual-nodulating S. rostrata and root-nodulating Sesbania cannabina. Acetylene-reduction activity expressed per gram of nodule dry weight was higher for stem nodules than for root nodules. Root nodule dry weight and acetylene-reduction activity failed to increase after stem inoculation, but root nodule dry weight and acetylene-reduction activity increased several fold within 15 days of detachment of aerial stem nodules. Stem nodulation, which occurred without inoculation under lowland field condition, suppressed root nodulation, thus accounting for more than 75% of total nitrogenase activity. Sesbania rostrata showed higher acetylene-reduction activity than S. cannabina. In dual-nodulating plants, root and stem nodules appeared to strike a balance in competition for energy, which may be controlled by stem nodulation. Key words: Sesbania rostrata, Azorhizobium caulinodans, stem nodule, root nodule, acetylene-reducing activity.

Stomatal conductance, photosynthesis and acetylene reduction rate in soybean genotypes

1992 ◽  
Vol 72 (2) ◽  
pp. 383-390 ◽  
Author(s):  
A. Djekoun ◽  
C. Planchon
Keyword(s):  
Glycine Max ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Leaf Water ◽  
Acetylene Reduction Activity ◽  
Reduction Activity ◽  
Leaf Osmotic Potential ◽  
Glycine Max L

Yield limitation in soybean (Glycine max L. Merr.) can result from decreases in photosynthesis and N2 fixation during periods of water deficiency. In this study, the relationships among stomatal conductance, photosynthesis and N2 fixation were analyzed in connection with drought tolerance of genotypes. Plants were grown in pots and exposed to field conditions. Carbon dioxide exchange rate was measured by gas analysis and nodule activity by the acetylene reduction method. Leaf water status was determined with a pressure bomb, and nodule water potential and leaf osmotic potential were measured psychrometrically. The differing tolerances of the cultivars Kingsoy and Hodgson to leaf water deficit resulted in a more or less developed ability of the lower side of the leaf to maintain good stomatal conductance during water stress. Stomatal conductance affects photosynthetic rate directly and acetylene reduction activity indirectly. Early stomatal closure, by limiting H2O exchange, contributes to conservation of nitrogenase activity. On the contrary, maintenance of high conductance during a water stress decreases soil water availability and nodule water content, which in turn has a decisive and limiting effect on acetylene reduction activity. Thus, if tolerance at low leaf water potentials associated with osmotic adjustment is an important drought mechanism for maintaining photosynthetic processes under water-limited conditions, the result would be obtained at the expense of symbiotic N2 fixation.Key words: Glycine max L. Merr., nitrogenase activity, photosynthesis, drought stress, soybean

Cloning and characterization of the nifA gene from Herbaspirillum seropedicae strain Z78

1991 ◽  
Vol 37 (6) ◽  
pp. 425-429 ◽  
Author(s):  
Emanuel M. Souza ◽  
Shigehiro Funayama ◽  
Liu U. Rigo ◽  
Fábio O. Pedrosa
Keyword(s):  
Nitrogen Fixation ◽  
Azospirillum Brasilense ◽  
Genomic Library ◽  
Acetylene Reduction Activity ◽  
Nif Genes ◽  
Herbaspirillum Seropedicae ◽  
Reduction Activity ◽  
Nitrogen Fixation Gene ◽  
Nifa Gene

A genomic library of Herbaspirillum seropedicae was constructed and screened for the nifA gene by complementation of a nifA mutant of Azospirillum brasilense (FP10). A recombinant plasmid, pEMS1, capable of restoring acetylene reduction activity in the mutant FP10, was isolated and found to hybridize to the nifA gene of Klebsiella pneumoniae. The results suggest that nifA is involved in the regulation of nif genes in H. seropedicae. Key words: diazotroph, nitrogen fixation gene, nif regulation, complementation cloning, Herbaspirillum seropedicae.

Nitrogenase activity, nodulation and seed production inVicia fabaas affected by methabenzthiazuron

1996 ◽  
Vol 127 (3) ◽  
pp. 319-324 ◽  
Author(s):  
J. Martínez ◽  
D. Vidal ◽  
E. Simón
Keyword(s):  
Seed Production ◽  
Vegetative Growth ◽  
Nitrogenase Activity ◽  
Dry Weight ◽  
Inhibitory Effect ◽  
Acetylene Reduction Activity ◽  
N Recovery ◽  
N Fixation ◽  
N Content ◽  
Reduction Activity

SUMMARYThe effects of recommended application rates of the herbicide methabenzthiazuron (MBT) (2·5 and 4 kg ha-1) on vegetative growth, nodulation and N2fixation in faba bean plants were studied in the field at Barcelona during 1990 and 1991. Nodulation, specific nitrogenase activity (SNA) of excised nodules, dry weight of plants and seed nitrogen content at harvest were compared in MBT-treated, hand-weeded (HW) and control plants. In 1990 the higher MBT application (4 kg ha-1) caused a decrease in nodulation and acetylene reduction activity (ARA) per plant during the mid-period of pod-fill, and also in vegetative growth, seed production and N content of seeds, whereas the lower rate (2·5 kg ha-1) did not have a significant effect on any of these factors. However, in 1991, growth and herbicide effects were different from those in the previous year. No inhibitory effect of MBT on nodulation, SNA or ARA per plant was observed and vegetative growth, seed production and N content of seeds were not significantly different from those of plants from HW plots. In 1991, both 4 kg ha-1of MBT and the HW treatment caused a stimulatory effect on seed N recovery and yield compared to control plants. Rates of ARA per plant at late pod-fill were positively related to N recovery by seeds. These differences could have been due to the low rainfall in 1990, which may have permitted MBT to remain in the soil for a longer period and to inhibit N fixation and plant growth in theVicia fabacrop.

NifHgene diversity and expression in a microbial mat community on the McMurdo Ice Shelf, Antarctica

2009 ◽  
Vol 22 (2) ◽  
pp. 117-122 ◽  
Author(s):  
Anne D. Jungblut ◽  
Brett A. Neilan
Keyword(s):  
Acetylene Reduction ◽  
Microbial Mats ◽  
Phylogenetic Analyses ◽  
Nitrogen Sources ◽  
Acetylene Reduction Activity ◽  
Ice Shelf ◽  
Bacterial Phyla ◽  
Reduction Activity ◽  
Gene Transcripts ◽  
Dimethyl Urea

AbstractN2-fixation is an important mechanism in microbial mats of the McMurdo Ice Shelf as nitrogen sources are limited. Here we applied molecular analyses of the N2-fixing diversity in cyanobacterial dominated microbial mats in a meltwater pond, known as Orange Pond, on the McMurdo Ice Shelf. Phylogenetic analyses ofnifHgenes andnifHgene transcripts were performed in association with acetylene reduction assay measurements. Eighteen phylotypes with the highest similarities to cyanobacteria, firmicutes, beta-, gamma- and deltaproteobacteria, spirochaetes and verrumicrobia were identified. All cyanobacterialnifHphylotypes grouped solely in the genusNostocspp. Clone-library analysis ofnifHgene transcripts only identified sequences with a highest match toNostocspp. and acetylene reduction activity was identified in the presence of light and absence of 3-(3,4-dichlorophenyl)-1,1-dimethyl urea. These molecular results indicate that a variety of bacterial phyla possess the ability to fix nitrogen. However, under the tested conditions the only organisms actively transcribingnifHgenes wereNostocspp. This underlines the importance ofNostocfor the nitrogen budget on the McMurdo Ice Shelf.

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