Effect of oxygen on batch and continuous cultures of a nitrogen-fixing Arthrobacter sp.

1979 ◽  
Vol 25 (6) ◽  
pp. 746-751 ◽  
Author(s):  
Isabella Cacciari ◽  
Daniela Lippi ◽  
Lucien M. Bordeleau
Keyword(s):  
Respiration Rate ◽  
Acetylene Reduction ◽  
Respiratory Activity ◽  
Nitrogenase Activity ◽  
Nitrogen Fixing ◽  
Anaerobic Conditions ◽  
Continuous Cultures ◽  
Partial Pressures ◽  
Oxygen Tensions ◽  
Effect Of Oxygen

Growth, acetylene reduction, and respiration rate were studied in batch and continuous cultures of Arthrobacter fluorescens at different oxygen partial pressures. The optimum pO2 values for growth and acetylene reduction were 0.05 and 0.025 atm, respectively, but microorganisms can tolerate higher pO2 values. The growth of cultures provided with combined nitrogen was dependent on oxygen availability, and strict anaerobic conditions did not support growth. Acetylene reduction of a population grown in continuous culture and adapted to low pO2 (0.02 atm) was much more sensitive to oxygenation than that of a population adapted to high pO2 (0.4 atm). Their maximum nitrogenase activity, at their optimal pO2 values, were quite different. The respiratory activity of nitrogen-fixing cultures increased with increasing oxygen tensions until a pO2 of 0.2 atm. At higher pO2 values, the respiration rate began to decrease.

Investigations of nitrogenase activity in rheotrophic peat

1976 ◽  
Vol 22 (10) ◽  
pp. 1561-1566 ◽  
Author(s):  
George John Waughman
Keyword(s):  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Anaerobic Bacteria ◽  
Organic Soils ◽  
Nitrogen Fixing ◽  
Anaerobic Conditions ◽  
Time Courses ◽  
Aerobic And Anaerobic ◽  
Stimulation Of

Acetylene reduction by the peat microflora was unaffected by light, but was sensitive to temperature, with an optimum of about 30 °C. The nitrogenase was inactivated by exposure to temperatures above about 35 °C. Activity occurred in completely anaerobic conditions; the rate of ethylene production was of the order of 0.5 nmol C2H4 ml−1h−1. Experiments with time courses indicated that exposure to oxygen caused an initial inhibition of activity followed by a period in which ethylene production was stimulated to rates much higher than in the anaerobic tests; both the inhibition and stimulation appeared to be related to the level of oxygenation. It is suggested that these results could be explained by the existence of nitrogen-fixing associations of aerobic and anaerobic bacteria in the peat. The stimulation of activity caused by exposure to air indicates that care must be taken when interpreting results of the assay obtained from waterlogged organic soils.

scholarly journals Influence of Partial Pressures of Acetylene and Nitrogen upon Nitrogenase Activity of Species of Beijerinckia

1977 ◽  
Vol 30 (6) ◽  
pp. 593 ◽  
Author(s):  
IC MacRae
Keyword(s):  
Nitrogen Fixation ◽  
Spectrophotometric Method ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Optical Emission ◽  
Molar Ratios ◽  
Partial Pressures ◽  
Beijerinckia Indica

Acetylene reduction and nitrogen fixation by strains of Beijerinckia indica and B. lacticogenes increased with increased partial pressures of acetylene and nitrogen up to 80 kPa. The optical emission spectrophotometric method was used for the determination of 14N : 15N ratios. The molar ratios of acetylene to nitrogen varied greatly from the theoretical value.

Nitrogen fixation by Klebsiella grown in the presence of oxygen

1972 ◽  
Vol 18 (12) ◽  
pp. 1845-1850 ◽  
Author(s):  
Robert Klucas
Keyword(s):  
Nitrogen Fixation ◽  
Dissolved Oxygen ◽  
Nitrogenase Activity ◽  
Fixed Nitrogen ◽  
Submerged Cultures ◽  
Continuous Cultures ◽  
Dissolved Oxygen Tension ◽  
Whole Cells ◽  
Oxygen Effects ◽  
Oxygen Tensions

Several facultative asymbiotic N2-fixing bacteria exhibited nitrogenase activity when grown in the presence of air and a limiting amount of fixed nitrogen. One isolate (S-4) identified as Klebsiella was examined in more detail for oxygen effects. Nitrogenase was not detectable in highly aerated submerged cultures but was detectable in shaken and continuous cultures at dissolved oxygen tensions of 3 and 10 mm of Hg respectively. No nitrogenase activity was found in cells from continuous cultures maintained at a dissolved oxygen tension of 15 mm of Hg or above. The nitrogenase activity in whole cells was not oxygen dependent but was oxygen tolerant.

A comparison of carbon source utilization for growth and nitrogenase activity in two Frankia isolates

1986 ◽  
Vol 32 (4) ◽  
pp. 353-358 ◽  
Author(s):  
Mary F. Lopez ◽  
Patricia Young ◽  
John G. Torrey
Keyword(s):  
Nitrogen Fixation ◽  
Carbon Source ◽  
Oxygen Uptake ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Carbon Sources ◽  
Alnus Rubra ◽  
Nitrogen Fixing ◽  
Pure Cultures

The carbon source requirements for the growth and nitrogen fixation of two morphologically distinct Frankia isolates were examined. Isolate ArI3 (from Alnus rubra) grew well on propionate, malate, acetate, and trehalose, and isolate CcI2 (from Casuarina cunninghamiana) grew best on pyruvate, acetate, and propionate. In general, the same carbon sources that supported growth supported both the development of vesicles and nitrogenase activity in long-term induction experiments in both isolates. However, ArI3 cultures induced on proprionate had 7 to 26 times the activity of other carbon sources and ArI3 cultures induced on acetate did not develop any detectable acetylene reduction. In a parallel set of experiments, cultures of both isolates were induced for nitrogenase activity on propionate and the resulting nitrogen fixing cultures were washed free of the organic acid by centrifugation. The washed cultures were incubated in the presence of various carbon sources to determine the ability of a particular substrate to supply energy directly for nitrogen fixation when vesicles and nitrogenase were already present. As was observed in the long-term induction experiments, pyruvate, propionate, and acetate supported the greatest activity in CcI2. Succinate and malate supported the greatest activity in ArI3, and propionate had very little stimulation of acetylene reduction. The reason for the lack of stimulation by propionate for washed cells of ArI3 was unclear but may have been due to toxic concentrations of the organic acid. In an attempt to compare the carbon utilization of ArI3 in pure culture with that in the alder symbiosis, oxygen uptake in the presence of various carbon sources of vesicles clusters isolate from Alnus rubra nodules inoculated with ArI3 was compared with the oxygen uptake of nitrogen-fixing pure cultures of ArI3. The oxygen uptake of the isolated vesicle clusters was stimulated by sucrose, trehalose, and glucose, but not by a variety of organic acids. In comparison, nitrogen-fixing pure cultures of ArI3 readily oxidized sugars and organic acids.

Estimating Nitrogenase Activity of Faba Bean (Vicia faba) by Acetylene Reduction (Ar) Assay

1990 ◽  
Vol 17 (5) ◽  
pp. 489 ◽  
Author(s):  
Herdina ◽  
JH Silsbury
Keyword(s):  
Diurnal Variation ◽  
Vicia Faba ◽  
Faba Bean ◽  
Closed System ◽  
N2 Fixation ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Electron Flow ◽  
Specific Rate ◽  
Rooting Medium

Methods of conducting acetylene reduction (AR) assay were appraised for estimating the nitrogenase activity of nodules of faba bean (Vicia faba L.). Factors considered were: (i) disturbance of plants when removing the rooting medium; (ii) assay temperature; (iii) the use of whole plants rather than detached, nodulated roots; (iv) diurnal variation in nodule activity; and (v) a decline in C2H4 production after exposure to C2H2. Plants growing in jars of 'oil dry' (calcined clay) had the same AR activity when assayed in situ in a closed system as when assayed after removal of the rooting medium. Assay temperatures of 12.5, 17.5 and 22.5°C influenced the specific rate of AR with the optimum at 17.5°C. Removal of the shoot resulted in a rapid decrease in AR activity in both vegetative and reproductive plants but the effect was much larger in the latter. AR and respiration by nodulated roots were closely linked and both varied markedly over a diurnal 12 h/12 h cycle. Since no fluctuation was found after nodules were detached, diurnal variation in the respiration of nodulated roots is attributed to change in nodule activity. Half of the dark respiration of nodulated roots was associated with respiration of the nodules and thus largely with N2 fixation. Since the AR assay provides no information on how electron flow in vivo is partitioned between reduction of N2 and reduction of protons, diurnal variation in hydrogen evolution (HE) in air and Ar/O2 in an open system was used to estimate this partitioning. Diurnal variation in apparent N2 fixation estimated in this manner was examined at a 'low' PPFD (300 μmol m-2 s-1) and at 'high' (1300 μmol m-2 s-1) to explore whether variation could be attributed to change in carbohydrate supply. Although HE in air and in Ar/O2 were both closely linked with the respiration of the nodulated root, apparent N2 fixation showed only a slight diurnal variation at 'low' light and almost none at 'high'. Vegetative plants showed no C2H2-induced decline in activity with exposure to C2H2 but reproductive plants did. This difference appears to be an age effect rather than attributable to flowering per se, since a decline occurred even when plants were kept vegetative by disbudding. A closed system for AR assay appears satisfactory for vegetative faba bean but such an assay over a 40-min period during the reproductive stage would underestimate nitrogenase activity by about 20%.

Dinitrogen fixation and nodulation by Frankia in Alnus incana as affected by inorganic nitrogen in pot experiments with peat

1983 ◽  
Vol 61 (11) ◽  
pp. 2956-2963 ◽  
Author(s):  
U. Granhall ◽  
T. Ericsson ◽  
M. Clarholm
Keyword(s):  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Inorganic Nitrogen ◽  
Experimental Period ◽  
Alnus Incana ◽  
Nitrogen Application ◽  
Noticeable Effect ◽  
Essential Nutrients ◽  
Pot Experiments ◽  
Ph Level

The effects of single large or repeated, exponentially increasing applications of nutrients, with or without inorganic nitrogen and at two pH levels, on the growth, nodulation, acetylene reduction, and nutrient uptake in Alnus incana (L.) Moench were investigated in pot experiments with peat under controlled laboratory conditions. The repeated application of inorganic nitrogen did not suppress nitrogenase activity until the last 2 weeks, whereas an initial, large, nitrogen application effectively inhibited nodulation and activity throughout the 40-day experimental period. The mode of nitrogen application was thus found to be more important than the total amounts applied. Shoot length, leaf area, shoot–root relations, dry-matter production, and nitrogen contents of plants were determined at the end of the experiment, as well as the effect of Frankia inoculations. Nitrogenase activity was determined three times, at 0, 3, and 5 weeks. N2 fixation (balance/acetylene reduction) was found to be maximal, 55% of total nitrogen uptake, in minus-N pots with single applications of essential nutrients. The fastest growth was, however, noted in pots with single applications of all nutrients, including N. Among the latter, pots inoculated with Frankia showed the best growth, in spite of low nitrogenase activity. The only noticeable effect of a raised pH level was a reduced endophyte activity in minus-N pots with single applications of essential nutrients, due to increased N mineralization in the peat.

scholarly journals Rhizobium tropici Genes Involved in Free-Living Salt Tolerance are Required for the Establishment of Efficient Nitrogen-Fixing Symbiosis with Phaseolus vulgaris

2002 ◽  
Vol 15 (3) ◽  
pp. 225-232 ◽  
Author(s):  
Joaquina Nogales ◽  
Rosario Campos ◽  
Hanaa BenAbdelkhalek ◽  
José Olivares ◽  
Carmen Lluch ◽  
...  
Keyword(s):  
Salt Tolerance ◽  
Phaseolus Vulgaris ◽  
Environmental Changes ◽  
Nitrogenase Activity ◽  
Regulation Of Gene Expression ◽  
Elongation Factor ◽  
Regulatory System ◽  
Trna Synthetase ◽  
Nitrogen Fixing ◽  
Rhizobium Tropici

Characterization of nine transposon-induced mutants of Rhizobium tropici with decreased salt tolerance (DST) allowed the identification of eight gene loci required for adaptation to high external NaCl. Most of the genes also were involved in adaptation to hyperosmotic media and were required to overcome the toxicity of LiCl. According to their possible functions, genes identified could be classified into three groups. The first group included two genes involved in regulation of gene expression, such as ntrY, the sensor element of the bacterial ntrY/ntrX two-component regulatory system involved in regulation of nitrogen metabolism, and greA, which encodes a transcription elongation factor. The second group included genes related to synthesis, assembly, or maturation of proteins, such as alaS coding for alanine-tRNA synthetase, dnaJ, which encodes a molecular chaperone, and a nifS homolog probably encoding a cysteine desulfurase involved in the maturation of Fe-S proteins. Genes related with cellular build-up and maintenance were in the third group, such as a noeJ-homolog, encoding a mannose-1-phosphate guanylyltransferase likely involved in lipopolysaccharide biosynthesis, and kup, specifying an inner-membrane protein involved in potassium uptake. Another gene was identified that had no homology to known genes but that could be conserved in other rhizobia. When inoculated on Phaseolus vulgaris growing under nonsaline conditions, all DST mutants displayed severe symbiotic defects: ntrY and noeJ mutants were impaired in nodulation, and the remaining mutants formed symbiosis with very reduced nitrogenase activity. The results suggest that bacterial ability to adapt to hyper-osmotic and salt stress is important for the bacteroid nitrogen-fixing function inside the legume nodule and provide genetic evidence supporting the suggestion that rhizobia face severe environmental changes after their release into plant cells.

New marine nitrogen-fixing bacteria isolated from an eelgrass (Zostera marina) bed

1988 ◽  
Vol 34 (7) ◽  
pp. 886-890 ◽  
Author(s):  
Wung Yang Shieh ◽  
Usio Simidu ◽  
Yoshiharu Maruyama
Keyword(s):  
Zostera Marina ◽  
Nitrogenase Activity ◽  
Molecular Nitrogen ◽  
Exponential Growth Phase ◽  
Nitrogen Fixing ◽  
Low Oxygen ◽  
Nitrogen Fixing Bacteria ◽  
Nitrogen Fixation Activity ◽  
The Family ◽  
Ph Decrease

Four strains of marine nitrogen-fixing bacteria were isolated from the roots of eelgrass (Zostera marina) and from sediments in an eelgrass bed in Aburatsubo Inlet, Kanagawa Prefecture, Japan. Significant levels of nitrogenase activity were detected in all four strains after a few hours of incubation under anaerobic conditions. Nitrogenase activity in all cases was Na+ dependent. These strains grew anaerobically or under conditions of low oxygen, using molecular nitrogen as the sole nitrogen source. Bacterial growth in liquid nitrogen-free medium was accompanied by a marked pH decrease during the exponential growth phase. Neither yeast extract nor vitamins were required for the nitrogen fixation activity of these strains. Taxonomically, all strains were facultatively anaerobic, Gram-negative rods. They were motile in liquid medium by means of a single polar flagellum and required NaCl for their growth. These characteristics, as well as the guanine + cytosine content of their DNA (43.5 – 44.8 mol%), placed them in the family Vibrionaceae. These strains, however, could not be identified to the genus level because they were distinct from the two halophilic genera Vibrio and Photobacterium of the family Vibrionaceae by a variety of characteristics.

Nitrogen fixation (acetylene reduction) by Klebsiella pneumoniae in association with 'Park' Kentucky bluegrass (Poa pratensis L.)

1981 ◽  
Vol 27 (1) ◽  
pp. 52-56 ◽  
Author(s):  
L. V. Wood ◽  
R. V. Klucas ◽  
R. C. Shearman
Keyword(s):  
Nitrogen Fixation ◽  
Klebsiella Pneumoniae ◽  
Ethylene Production ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Poa Pratensis ◽  
Kentucky Bluegrass ◽  
Surface Sterilization ◽  
Reducing Activity ◽  
Acetylene Reducing Activity

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.

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