Inhibition Of Nitrogen Fixation Research Articles

Effects of Airborne Particulates on Nitrogen Fixation in Legumes and Algae

This paper presented some of the effects of anthropogenic sulfur compounds along with the phytotoxic elements in the stack emissions from coal-fired electrical facilities and smelters on diazotrophic processes. S0/sub 2/ damage to conifers is evident for 48.3 km (30 miles) north of the present smelter site. Inhibition of nitrogen fixation by SO/sub 2/ or its oxidation products involves either a direct effect on nitrogenase or on photosynthesis. In either case, the result is an increased dependence on combined soil nitrogen for growth. Data presented in Fig. 3 for anabaena suggest that nitrogenase is more sensitive to acid rain than is the photosynthetic mechanism. Treatment of anabaena with sodium bisulfite solutions at pH 5.3 effected a 30% reduction of N/sub 2/ fixation at 1 ppM HSO/sub 3/ which is equivalent to 9 ppB SO/sub 2/. The loss of any combined nitrogen in the already nitrogen-poor grassland soils would be expected to reduce yields of rangeland grasses. Similarly, the loss of the nitrogen contributions by the soil-binding terricolous lichens would be serious. The utility industries suggest that any loss of combined nitrogen derived from diazotrophs would be supplied via NO/sub 3/ from stack emissions as the oxidation products of NO/sub 3/more » would be available to the plants. Recall that the nitrogenase activity is reduced by the addition of combined nitrogen. However, the scenario, based on ecological principles, would predict that the diazotrophs would lose their physiological advantage and disappear from a system in which combined nitrogen was supplied by industrial emissions resulting in a dependence on anthropogenic nitrogen which is emitted along with other phytotoxicants. Should the anthropogenic source cease, the stage for a biological catastrophe is set with resulting desertification of the fumigated plains ecosystem.« less

Plant and nodule development and nitrogen fixation in climbing cultivars of Phaseolus vulgaris L. grown in monoculture, or associated with Zea mays L.

SummaryPlant and nodule development and nitrogen fixation were studied in two climbing cultivars of Phaseolus vulgaris, grown in monoculture, or associated with two maize populations differing in growth characteristics.Bean cultivar P590 showed similar plant and pod fresh weight development in monoculture and when associated with a vigorous landrace maize, interspecific competition becoming significant only 92 days after planting. Nitrogen (C2H2) fixation in this cultivar was greatest 68 days after planting and declined rapidly thereafter, showing no significant differences between monoculture and associated plantings. When the bean cultivar P526 was associated with the landrace maize, plant development was depressed as early as 50 days after planting. While slight inhibition of nitrogen fixation, specific nodule activity (SNA) and nodule carbohydrate content was also observed at this time, it could not be concluded that such inhibition was definitely due to the associated planting.Association with an improved maize, amarillo subtropical, did not affect plant development in P590 but did decrease growth of P526 at the 80 and 92 day harvests.

Pesticide (hexachlorocyclohexane) inhibition of growth and nitrogen fixation in blue-green algae Anabaenopsis raciborskii and Anabaena aphanizomenoides.

The effects of the pesticide hexachlorocyclohexane (HCH) on the nitrogen fixing blue-green algae Anabaenopsis raciborskii and Anabaena aphanizomenoides commonly found as blooms in fish ponds were studied. These algae were very sensitive to HCH, and a distinct decrease in growth rate was observed on prolonged incubation. Lower concentrations (10 microgram/ml) were algistatic and higher concentrations (60 microgram/ml) were algicidal. The inhibition of nitrogen fixation indicated that the presence of HCH might affect overall nitrogen economy of inland waters.

Pesticide (hexachlorocyclohexane) inhibition of growth and nitrogen fixation in blue‐ green algae Anabaenopsis raciborskii and Anabaena aphanizomenoides

AbstractThe effects of the pesticide hexachlorocyclohexane (HCH) on the nitrogen fixing blue‐green algae Anabaenopsis raciborskii and Anabaena aphanizomenoides commonly found as blooms in fish ponds were studied. These algae were very sensitive to HCH, and a distinct decrease in growth rate was observed on prolonged incubation. Lower concentrations (10 μg/ml) were algistatic and higher concentrations (60 μg/ml) were algicidal. The inhibition of nitrogen fixation indicated that the presence of HCH might affect overall nitrogen economy of inland waters.

Interaction between the nitrate respiratory system of [formula omitted] K12 and the nitrogen fixation genes of [formula omitted

Hybrids were constructed between E. coli K12 chl − mutants defective in nitrate respiration and an F′ plasmid carrying nitrogen fixation genes from K. pneumoniae . Examination of these hybrids showed that expression of nif Kp + genes does not require a functional nitrate respiratory system, but that nitrate reductase and nitrogenase do share some Mo-processing functions. For nitrate repression of nitrogenase activity, reduction of nitrate to nitrite is not necessary, but the Mo-X cofactor encoded by chl genes is essential. Nitrate probably inhibits nitrogen fixation by affecting the membrane relationship of the nitrate and fumarate reduction systems such that the membrane cannot be energized for nitrogenase activity.

The combined relationship of temperature and molybdenum concentration to nitrogen fixation byAnabaena cylindrica

The joint effects of growth temperature, incubation temperature, and molybdenum concentration on the nitrogen fixation rate ofAnabaena cylindrica were determined using the acetylene-reduction technique. The nitrogen-fixation response to increased molybdenum concentration varied among three growth temperatures (15°, 23°, and 30° C). The pattern of rate change was similar within a growth temperature but increased overall in magnitude with the three incubation temperatures (also 15°, 23°, and 30° C). The maximum rate of nitrogen fixation occurred at 30°C regardless of previous growth temperature. The minimum molybdenum concentration necessary to yield substantial acetylene reduction varied with growth temperature: at 15°C, 15μg 1(-1) was effective; at 23°C, less than 5μg 1(-1) was effective; and at 30°C, 50μg 1(-1) was effective. At all three growth temperatures, increases in molybdenum concentration above the minimum effective concentration produced increases in acetylene reduction. However, at higher molybdenum concentrations inhibition of nitrogen fixation occurred.

Alfalfa Root Nodule Distribution and Inhibition of Nitrogen Fixation by Heat1

AbstractGreenhouse and field trials were done to test the likelihood that impairment of N fixation contributes to late summer decline in productivity of Medicago sativa L.In greenhouse solution cultures, acetylene reduction and N fixation by nodules were impaired by daily heating of the culture solutions to 32 C, and eliminated by repeated exposures to 36 C or a single exposure to 40 C. However, in a field trial conducted on a Yolo silt loam (Typic Xerorthent, fine silty mixed non‐acid thermic), alfalfa showed no signs of N deficiency and responded little to application of 500 kg NH4NO3/ha although soil temperatures above 32 C were recorded for 5 to 6 hours each day during a 6‐day hot spell following a late summer cut, with peak soil temperatures above 40 C at 2 cm depth.Lack of response in the field trial is explained by observations of temperature profiles and nodule distribution. Only the topmost 5 cm of soil heated above 30 C, and this contained less than 10% of the nodules. Most of the nodules were at depth 10 to 30 cm, and remained at nearly optimal temperatures of 22 C to 27 C.Heat inhibition of nitrogen fixation should not significantly limit growth of alfalfa in the field unless nodule‐formation is constrained to shallow depths.

ACIDIFICATION OF A LUVISOLIC SOIL CAUSED BY LOW-RATE, LONG-TERM APPLICATIONS OF FERTILIZERS AND ITS EFFECTS ON GROWTH OF ALFALFA

Soil samples collected from the Breton plots, which had received various treatments and had been cropped to a 5-yr rotation of cereals and forages over a 40-yr period, were analyzed to determine the effects of the treatments on soil acidity. Treatments included applications of fertilizers at low rates, infrequent applications of lime, applications of manure and applications of various combinations of these. Those receiving NS, NPS and NPKS were more acidic than the check plots and those receiving lime, lime + NPKS and P as 0–45–0 were less acidic. Plots treated with manure or manure + NPKS were not acidified. Since 1967, a brome–alfalfa mixture has been seeded and on the more acidic plots the established stand contained less than 30% alfalfa as compared to greater than 70% in the lime or P (0–45–0) treatments. Liming one half of each plot in each series in 1972 significantly increased the stand and reduced the aluminum content of alfalfa, especially in the more acidic plots. Alfalfa grown on these more acidic plots had, in general, higher Mn and Al and lower N contents than did alfalfa in the limed portions of the plots. The poor growth of alfalfa on plots receiving NS, NPS and NPKS is attributed to the acidifying effects of the fertilizers being sufficient to inhibit nitrogen fixation and induce some toxic concentrations of Al and Mn in the soil.

Comparison of Nitrogen Fixation Activity in Tall and Short Spartina alterniflora Salt Marsh Soils

A comparison of the N(2) fixers in the tall Spartina alterniflora and short S. alterniflora marsh soils was investigated. Zero-order kinetics and first-order kinetics of acetylene reduction were used to describe the activity of the N(2) fixers in marsh soil slurries. It was found that the V(max) values were approximately 10 times greater for the N(2) fixers in the tall Spartina than in the short Spartina marsh when raffinose was used as the energy source. In addition, the (K(s) + S(n)) values were approximately 4 to 15 times lower for the N(2) fixers in the tall Spartina than in short Spartina marsh. First-order kinetics of nitrogen fixation for several substrates indicate that the N(2) fixers in the tall Spartina marsh were two to seven times more active than those in the short Spartina marsh. Ammonium chloride (25 mug/ml) did not inhibit nitrogen fixation in the tall Spartina marsh, but there was a 50% inhibition in nitrogen fixation in the short Spartina marsh. On the other hand, sodium nitrate inhibited nitrogen fixation almost 100% at 25 mug/ml in both soil environments. Amino nitrogen (25 to 100 mug/ml) had little or no effect on nitrogen fixation. The results indicate that the N(2) fixers in the tall Spartina marsh were physiologically more responsive to nutrient addition than those in the short Spartina marsh. This difference in the two populations may be related to the difference in daily tidal influence in the respective areas and thus provide another explanation for the enhanced S. alterniflora production in the creek bank soil system.

Nitrate effects on the nodulation of legumes inoculated with nitrate-reductase-deficient mutants of Rhizobium

The effect of nitrate on the symbiotic properties of nitrate-reductase-deficient mutants of a strain of cowpea rhizobia (32H1), and of a strain of Rhizobium trifolii (TA1), were examined; the host species were Macroptilium atropurpureum (DC.) Urb. and Trifolium subterraneum L. Nitrate retarded initial nodulation by the mutant strains to an extent similar to that found with the parent strains. It is therefore unlikely that nitrite produced from nitrate by the rhizobia, plays a significant role in the inhibition of nodulation by nitrate. Nitrite is an inhibitor of nitrogenase, and its possible production in the nodule tissue by the action of nitrate reductase could be responsible for the observed inhibition of nitrogen fixation when nodulated plants are exposed to nitrate. However, the results of this investigation show that nitrogen fixation by the plants nodulated by parent or mutant strains was depressed by similar amounts in the presence of nitrate. No nitrite was detected in the nodules. Nodule growth, and to a lesser extent, the nitrogenase specific activity of the nodules (μmol C2H4g(-1) nodule fr. wt. h(-1)), were both affected by the added nitrate.

Effect of 7-Azatryptophan on Nitrogen Fixation and Heterocyst Formation in the Blue-green Alga Anabaena cylindrica

In the blue-green alga Anabaena caienula, 7-azatryptophan was shown to alter the pattern of heterocyst formation in two ways: (a) the number of these specialized cells is increased, (b) groups of adjacent heterocysts are formed. The present communication extends these observations on the morphological changes to the blue-green alga Anabaena cylindrica . Moreover, nitrogen fixation activities are observed to increase parallel with the formation of new heterocysts when Anabaena is grown in the presence of 1—5, µ M azatryptophan indicating that the heterocysts are the main site of nitrogenase in these aerobically grown cultures. Kinetic studies show that azatryptophan first affects nitrogen fixation. This inhibition is followed by an increase in the number of heterocysts and finally by a recovery of the nitrogen fixation activity beyond that of control algae grown without the tryptophan analogue. Azatryptophan specifically inhibits nitrogen fixation in Anabaena, since it does not affect ammonia-grown Anabaena cylindrica or nitrogen fixing Klebsiella pneumoniae .

Effect of IAA on Growth and Nitrogen Fixation of Westiellopsis prolifica Janet

Observations have been made in pure cultures to explore the effect of Indole-3-acetic acid (IAA) on the growth and nitrogen fixation of Westiellopsis prolifica a blue-green alga. IAA stimulates the growth and increases chlorophyll content but inhibits nitrogen fixation. The effect of IAA on nitrogen fixation is direct and independent of growth and chlorophyll content. The effect of Indole-3-acetic acid on the growth of blue-green algae has been reported by several workers (Bunt, 1961; Singh et al., 1965; Ahmad and Winter, 1968). The differentiation of heterocysts and spores was found to be stimulated in the presence of IAA in Anabaena ambigua (BAHAL et al., 1973) and Cylindrospermum majus (SINGH et al., 1965) respectively. The ecophysiological consideration of the effect of IAA on the algal population is of major importance as the soil contains a considerable amount of this hormone (MCLAREN and PETERSON, 1967). It was suspected that this hormone may be influencing on the nitrogen fixation of blue-green algae. The present work deals with the effect of IAA on the growth and nitrogen fixation of Westiellopsis prolifica a blue-green alga abundantly found in this locality.

Effects of SO2 on Photosynthesis and Nitrogen Fixation

AbstractResponses of photosynthesis and nitrogen fixation to NaHSO3 (10−5−5 × 10−3M) were investigated in the lichen Stereocaulon paschale (L.) Fr. and the blue‐green alga Anabaena cylindrica Lemmermann. The treatments were performed in buffered media with varying pH (5.8–8.1) and light conditions (0–32 W × m−2). The activities of the intact organisms were investigated, under the same environmental conditions, with 14C liquid scintillation and acetylene reduction techniques respectively.The nitrogen fixation proved to be more susceptible than photosynthesis, in both organisms, and in all cases treatments at pH 5.8 were more inhibitory than at higher pH‐values. Treatment with 5 × 10−4M NaHSO3 at pH 5.8 caused no reduction of photosynthesis in S. paschale, while the inhibition of nitrogen fixation was 97%. For A. cylindrica the corresponding values were 40% and 75% respectively. Short‐time treatments of A. cylindrica showed that the nitrogen fixation was more rapidly affected than photosynthesis. The inhibition of nitrogenase activity and CO2‐fixation was smaller in the dark and increased at higher light intensities. Both processes showed a good capacity for recovery after removal of the NaHSO3 solution. Also the clumping ability of A. cylindrica was disturbed by NaHSO3 treatments.

Nitrogen Fixation by Blue‐Green Algae‐Lichen Crusts in the Great Basin Desert

AbstractBlue‐green algae‐lichen crusts (Atriplex confertifolia, Eurotia lanata, and Artemisia tridentata sites) from the Great Basin Desert have a laboratory potential of fixing atmospheric nitrogen at rates up to 84 g of N ha‐1 hour‐1. Nitrogen fixation is optimal when the crust is moistened to ‐⅓ bar pressure, temperature is 19 to 23C, and the light intensity is 200 microeinsteins m‐2 sec‐1 with incandescent light. The acetylene reduction technique provided a useful assay to measure in situ nitrogen fixation which was correlated with potential values obtained in the laboratory under optimum conditions. Nitrogen fixation was found to be reduced under desert shrub canopies possibly due to allelopathic effects of the shrubs. Aqueous leaf extracts of desert shrubs significantly inhibited nitrogen fixation. Annual nitrogen fixed was estimated at 10 to 100 kg of N ha‐1 year‐1, depending upon microenvironmental conditions.

Inhibition of nitrogen fixation in salt marshes measured by acetylene reduction

Nitrogen fixation as estimated by acetylene reduction takes place in intertidal sand and mud in salt marshes and is inhibited by additions of nitrogenous compounds such as sewage sludge or urea. Fixers on the marsh use combined nitrogen available from other sources in preference to nitrogen fixation. Marshes can remove substantial amounts of nitrogen from eutrophic waters by this shift in the nitrogen cycle.

Effects of azide, thioglycollic acid, and nitrosoguanidine on growth and nitrogen fixation in different clones of the blue‐green alga Cylindrospermum majus

AbstractSodium azide and thioglycollic acid weakly inhibited nitrogen fixation in different clones of Cylindrospermum majus in continuous cultures.The growth of different clons of C. majus was slightly stimulated by azide and inhibited by thioglycollic acid and nitrosoguanidine.No mutants or morphological variations could be observed in the algal clones after treatment with a sub‐lethal dose ofnitrosoguanidine although growth and nitrogen fixation were inhibited or depressed.

Effects of azide, thioglycollic acid, and nitrosoguanidine on growth and nitrogen fixation in different clones of the blue-green alga Cylindrospermum majus.

Sodium azide and thioglycollic acid weakly inhibited nitrogen fixation in different clones of Cylindrospermum majus in continuous cultures. The growth of different clons of C. majus was slightly stimulated by azide and inhibited by thioglycollic acid and nitrosoguanidine. No mutants or morphological variations could be observed in the algal clones after treatment with a sub-lethal dose ofnitrosoguanidine although growth and nitrogen fixation were inhibited or depressed.

Poly- -hydroxybutyrate biosynthesis and the regulation of glucose metabolism in Azotobacter beijerinckii.

Azotobacter beijerinckii possesses the enzymes of both the Entner-Doudoroff and the oxidative pentose phosphate cycle pathways of glucose catabolism and both pathways are subject to feedback inhibition by products of glucose oxidation. The allosteric glucose 6-phosphate dehydrogenase utilizes both NADP(+) and NAD(+) as electron acceptors and is inhibited by ATP, ADP, NADH and NADPH. 6-Phosphogluconate dehydrogenase (NADP-specific) is unaffected by adenosine nucleotides but is strongly inhibited by NADH and NADPH. The formation of pyruvate and glyceraldehyde 3-phosphate from 6-phosphogluconate by the action of the Entner-Doudoroff enzymes is inhibited by ATP, citrate, isocitrate and cis-aconitate. Glyceraldehyde 3-phosphate dehydrogenase is unaffected by adenosine and nicotinamide nucleotides but the enzyme is non-specific with respect to NADP and NAD. Citrate synthase is strongly inhibited by NADH and the inhibition is reversed by the addition of AMP. Isocitrate dehydrogenase, a highly active NADP-specific enzyme, is inhibited by NADPH, NADH, ATP and by high concentrations of NADP(+). These findings are discussed in relation to the massive synthesis of poly-beta-hydroxybutyrate that occurs under certain nutritional conditions. We propose that synthesis of this reserve material, to the extent of 70% of the dry weight of the organism, serves as an electron and carbon ;sink' when conditions prevail that would otherwise inhibit nitrogen fixation and growth.

Absence of the pigments of photosystem II of photosynthesis in heterocysts of a blue-green alga.

ALL filamentous blue–green algae capable of fixing elementary nitrogen have heterocysts. Stewart et al.1 have strong evidence that these differentiated cells are the sites of nitrogen fixation. They did not, however, show that photosystem II, responsible for the evolution of molecular oxygen (O2), is not functional in heterocysts. Because high oxygen tension inhibits nitrogen fixation, heterocysts should not possess the pigments of photosystem II. Fay2 produced evidence in vitro suggesting that heterocysts do not contain c-phycocyanin (c-PC), a principal constituent of photosystem II. Stewart et al.1 found much less c-PC in heterocysts than normal cells and believed that photosystem II could be absent in heterocysts. Others3,4, however, have demonstrated the evolution of O2 from blue–green algae in the absence of c-PC. Thus the points to be resolved are whether heterocysts in vivo contain c-PC and the other pigments comprising photosystem II, and whether, in the absence of one or more of these, photosystem II is functional in heterocysts. A comparison of the in vivo pigment composition of normal cells and heterocysts has indicated that heterocysts lack a functional photosystem II.

Comparative Studies of Nitrogen Fixation by Soybean Root Nodules, Bacteroid Suspensions and Cell-free Extracts

SUMMARY: Rhizobium japonicum (CC711) was used to infect soybean seeds from which plants were grown. From the root nodules, bacteroid suspensions with initial rates of nitrogen fixation as high as those calculated for bacteroids in intact nodules were prepared. Oxygen, which was required for fixation by intact nodules and bacteroid suspensions, caused the eventual loss of bacteroid nitrogen-fixing ability, accompanied by an increase in O2-uptake. In intact nodules and in bacteroid suspensions, increasing O2 pressures resulted in higher values for K m of nitrogen fixation. V max also increased with increasing pO2 and this was shown to be consistent with the characteristics of nitrogen fixation by anaerobic cell-free extracts of bacteroids which required an energy source (ATP), and a reductant (sodium dithionite). Higher concentrations of carbon monoxide were required to inhibit nitrogen fixation by intact nodules than by bacteroid suspensions. Carbon monoxide was a competitive inhibitor of nitrogen fixation in bacteroid suspensions and Ki (CO) and Km (N2) values showed that the nitrogenase had about 30 times the apparent affinity for CO that it had for N2. In cell-free extracts of bacteroids, the nitrogen-fixing activity remained in the supernatant fluid after centrifugation at 100,000 g for 30 min. The extracts were inactivated at 0°. The Km for nitrogen fixation by cell-free extracts was variable, 62-118 (N2 concentration in mm. Hg. pressure), compared with 50-60 for intact nodules and 20 for intact bacteroids when Km for these was measured in the range of pO2 in which it was only slightly affected by O2. The Ki for inhibition of nitrogen fixation by CO in extracts was similar to values obtained with intact bacteroids.