Limiting Factors in Grass Nitrogen Fixation

Balandreau, J.; Ducerf, P.; Hamad-Fares, Ibtissam; Weinhard, P.; Rinaudo, Gérard; Millier, Claude; Dommergues, Yvon

doi:10.1007/978-1-4615-8957-0_20

Cited by 26 publications

(9 citation statements)

References 21 publications

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“…Results from ecological and physiological studies on Nz-fixing pseudomonads are insufficient for extrapolation to natural environments. Relevant information is therefore largely drawn from other aerobic heterotrophic N2-fixing systems [110][111][112][113] …”

Section: Limiting Factorsmentioning

confidence: 99%

N2-fixing pseudomonads and related soil bacteria

Chan

1994

FEMS Microbiology Reviews

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Pseudomonas-like organisms form a highly heterogeneous and ubiquitous group of bacteria. Recent identification of an authentic P~eudomonas genus should help to decrease difficulties which arose from taxonomic uncertainties. Further difficulties in recognising N2-fixing Pseudomonas species lie in the confirmation of diazotrophy. Optimised conditions are often needed for the detection of nitrogenase activity since it is controlled by specific environmental factors and physiological requirements. However, genetically constructed N2-fixing strains from authentic Pseudomonas species have demonstrated that at least some members of the genus possess mechanisms to accommodate and express nil (N z fixation) genes from a well-studied diazotroph, Klebsiella pneumoniae. Renowned for their catabolic versatility, pseudomonads can use a wide range of carbon and energy substrates. Hence, potential N2-fixing pseudomonads are conceivably less limited by carbon and energy sources available in the environment compared to other N2-fixing organisms. Pseudomonas species dominate in the rhizosphere of some plants from which isolates have been shown to be diazotrophic. Several strains are also chemolithotrophs, capable of using H 2 as energy and electron source and CO2 as carbon source. Besides assays for N2-fixing activity, DNA hybridisation to the well conserved molybdo-nitrogenase structural gene probe is an indicator of diazotrophy. However, absence of hybridisation to this probe, despite N 2 fixation activity, has been reported. Although the genetics of N 2 fixation in pseudomonads have hardly been studied, some nif genes have been shown to be plasmid-borne. Pseudomonas species are also predominant soil denitrifiers, reducing nitrate and nitrite to gaseous forms of nitrogen during anaerobic respiration. Hence, they play an important role in the global biological nitrogen cycle. Several diazotrophic species including a few pseudomonads can also denitrify. The potential contribution by Ne-fixing pseudomonads to the sinks and sources of soil nitrogen is considered small in the short term but essentially remains unclear in the absence of experimental data. Reliable rapid methods for their specific enumeration are indispensable for assessing their population dynamics and ascertaining their ecological significance.

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Section: Limiting Factorsmentioning

confidence: 99%

N2-fixing pseudomonads and related soil bacteria

Chan

1994

FEMS Microbiology Reviews

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“…Procedural variances are particularly evident in the methods used for sampling, sample preparation, and the conditions under which testing has been conducted. Examples of contrasting procedures can be found in comparing the studies of Döbereiner and Day (1976), Nelson et al (1976), Tjepkema and Bums (1976), Evans and Barber (1977), Balandreau et al (1978), Boyle andPatriquin (1980), and. In addition, highly variable results are frequently noted by individual investigators.…”

Section: Discussionmentioning

confidence: 93%

Evaluation and significance of associative dinitrogen fixation for arid soil rehabilitation

Wullstein

1989

Arid Soil Research and Rehabilitation

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There are indications that in soils of arid lands associative dinitrogen fixation may be an important factor in providing plants with nitrogen. The actual values of fixation rates and amounts of nitrogen accessible to vegetation are difficult to determine due to inherent difficulties with the commonly used acetylene reduction methodology. It appears, however, that the arid zone plant species forming rhizosheaths are best suited for rehabilitation purposes. The rhizosheath-forming plant species show more consistent and higher dinitrogen fixation rates than those without the rhizosheaths. In general, the phenomenon of dinitrogen fixation by root-associated, nonnodule-forming organisms is poorly understood. There is a dire need for experimental work with 15 N 2 in the field to ascertain the actual amounts of fixed dinitrogen delivered to vegetation in various environmental situations.

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“…Many reports have been published on the nonsymbiotic nitrogen fixation in the rhizosphere of upland plants (9)(10)(11)(12)(13), although the activities are often much smaller than those cultivated under submerged conditions (14,15).…”

Section: Discussionmentioning

confidence: 99%

Nitrogen Fixation and a Nitrogen-Fixing Bacterium From the Roots of Eragrostis Ferruginea

Nioh

1979

J. Gen. Appl. Microbiol.

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An appreciable amount of nitrogen-fixing (acetylene-reducing) activity was observed in the excised roots of graminaceous weed, Eragrostis ferruginea. The highest activity obtained at 5 % oxygen concentration was 26.8 nmol acetylene reduced/g/hr. From the excised root, an aerobic bacterial strain with rapid growth on nitrogen-deficient medium and high acetylene-reducing activity was obtained. The isolate, termed ER201, was Gram-negative nonmotile rod and resembled Azotobacter, although its taxonomic position is uncertain. Glucose, sucrose, ethanol, acetate, lactate, malate, pyruvate, and succinate supported its N2-dependent growth, while lactose, rhamnose, starch, xylose, glycerol, citrate, and p-hydroxybenzoate did not. At the expense of 1 g of glucose, 7.3 to 7.5 mg of nitrogen was fixed. Specific activity of the isolate for acetylene reduction was 37.7 nmol acetylene reduced per mg cell protein per min under 10.6 % oxygen concentration. The isolate failed to grow in nitrogen-deficient media with initial pH below 6.6, while its growth was abundant at pH 6.8 or higher.In a survey of nitrogen-fixing activities in the rhizosphere of herbaceous plants in Tokyo University Forest in Aichi, an appreciable amount of acetylenereducing activity was observed in the excised roots of graminaceous weed, Eragrostis ferruginea. A nitrogen-fixing bacterial strain was isolated from the roots and its characteristics were studied. MATERIALS AND METHODSPreparation of the plant root samples. E. ferruginea was collected several times from the field of the University Forest during May to July, 1977. Usually the root systems of 4 or 5 plants were supplied simultaneously. The root systems were cut off from the whole plant, mixed well, and, after gently shaking once in 261

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Limiting Factors in Grass Nitrogen Fixation

Cited by 26 publications

References 21 publications

N2-fixing pseudomonads and related soil bacteria

N2-fixing pseudomonads and related soil bacteria

Evaluation and significance of associative dinitrogen fixation for arid soil rehabilitation

Nitrogen Fixation and a Nitrogen-Fixing Bacterium From the Roots of Eragrostis Ferruginea

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