Acetylene reduction, H2 evolution and 15N2 fixation in the Alnus incana-Frankia symbiosis

Planta ◽  
1986 ◽  
Vol 167 (3) ◽  
pp. 382-386 ◽  
Author(s):  
A. Sellstedt
Keyword(s):  
Acetylene Reduction ◽  
Alnus Incana ◽  
H2 Evolution

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 Nitrogenase of Klebsiella pneumoniae. Distinction between proton-reducing and acetylene-reducing forms of the enzyme: effect of temperature and component protein ratio on substrate-reduction kinetics

1977 ◽  
Vol 167 (2) ◽  
pp. 457-461 ◽  
Author(s):  
R N F Thorneley ◽  
R R Eady
Keyword(s):  
Klebsiella Pneumoniae ◽  
Acetylene Reduction ◽  
Electron Flow ◽  
Turnover Time ◽  
Effect Of Temperature ◽  
Lag Phase ◽  
H2 Evolution ◽  
Protein Ratio ◽  
Substrate Reduction ◽  
Fe Protein

Non-linear rates of acetylene reduction and concomitant H2 evolution were observed for the nitrogenase of Klebsiella pneumoniae at 10 degrees C. A lag phase of 1-4 min, dependent on the ratio of Mo-Fe protein to Fe protein present, occurred before linear rates of acetylene reduction were achieved. A complementary burst phase for concomitant H2 evolution in the presence of acetylene was also observed. When the proton was the only reducible substrate present, linear rates of H2 evolution were observed. N2 was a poor substrate under these conditions. Similar lag and burst phases occurred at 30 degrees C, but only when a large molar excess of Mo-Fe protein with respect to Fe protein was present. The results at 10 degrees C show that the binding of acetylene to the enzyme stimulates electron flow, but that these electrons, which initially reduce protons, can only reduce acetylene after a lag phase that cannot be accommodated in the turnover time calculated under steady-state conditions.

scholarly journals Effect of Temperature on H2 Evolution and Acetylene Reduction in Pea Nodules and in Isolated Bacteroids

1985 ◽  
Vol 77 (2) ◽  
pp. 335-338 ◽  
Author(s):  
Hans Bertelsen
Keyword(s):  
Acetylene Reduction ◽  
Effect Of Temperature ◽  
H2 Evolution

Effects of elevated oxygen tensions on acetylene reduction in Alnus incana-Frankia symbioses

1988 ◽  
Vol 74 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Lis Rosendahl ◽  
Kerstin Huss-Danell
Keyword(s):  
Acetylene Reduction ◽  
Alnus Incana ◽  
Oxygen Tensions

scholarly journals Nitrogenase of Klebsiella pneumoniae nifV mutants. Investigation of the novel carbon monoxide-sensitivity of hydrogen evolution by the mutant enzyme

1983 ◽  
Vol 211 (3) ◽  
pp. 589-597 ◽  
Author(s):  
P A McLean ◽  
B E Smith ◽  
R A Dixon
Keyword(s):  
Klebsiella Pneumoniae ◽  
Acetylene Reduction ◽  
Competitive Inhibitor ◽  
H2 Production ◽  
Mutant Enzyme ◽  
Wild Type ◽  
H2 Evolution ◽  
Ph Optimum ◽  
Mofe Protein ◽  
Fe Protein

The MoFe protein of nitrogenase from Klebsiella pneumoniae nifV mutants, NifV- Kp1 protein, in combination with the Fe protein from wild-type cells, catalysed CO-sensitive H2 evolution, in contrast with the CO-insensitive reaction catalysed by the wild-type enzyme. The decrease in H2 production was accompanied by a stoicheiometric decrease in dithionite (reductant) utilization, implying that CO was not reduced. However, CO did not affect the rate of phosphate release from ATP. Therefore the ATP/2e ratio increased, indicating futile cycling of electrons between the Fe protein and the MoFe protein. The inhibition of H2 evolution by CO was partial; it increased from 40% at pH6.3 to 82% at pH 8.6. Inhibition at pH7.4 (maximum 73%) was half-maximal at 3.1 Pa (0.031 matm) CO. The pH optimum of the mutant enzyme was lower in the presence of CO. Steady-state kinetic analysis of acetylene reduction indicated that CO was a linear, intersecting, non-competitive inhibitor of acetylene reduction with Kii = 2.5 Pa and Kis = 9.5 Pa. This may indicate that a single high-affinity CO-binding site in the NifV- Kp1 protein can cause both partial inhibition of H2 evolution and total elimination of acetylene reduction. Various models to explain the data are discussed.

Utilization of the acetylene reduction assay to screen for tolerance of symbiotic N2 fixation to limiting P nutrition in common bean

1997 ◽  
Vol 99 (2) ◽  
pp. 227-232
Author(s):  
Vincent Vadez ◽  
Douglas P. Beck ◽  
Jesus H. Lasso ◽  
Jean-Jacques Drevon
Keyword(s):  
Common Bean ◽  
N2 Fixation ◽  
Acetylene Reduction ◽  
Acetylene Reduction Assay ◽  
Symbiotic N2 Fixation ◽  
P Nutrition ◽  
Reduction Assay

Response of nitrogenase to altered carbon supply in a Frankia-Alnus incana symbiosis

1991 ◽  
Vol 83 (3) ◽  
pp. 331-338 ◽  
Author(s):  
Per-Olof Lundquist ◽  
Kerstin Russ-Danell
Keyword(s):  
Alnus Incana ◽  
Carbon Supply

Study of Alnus incana L. Moench fruit extract biologically active substances influence on resistance development in mls-resistant staphylococci skin isolates

2018 ◽  
Vol 22 (2) ◽  
pp. 263-266
Author(s):  
R.V. Kutsyk ◽  
O.I. Yurchyshyn
Keyword(s):  
Selective Pressure ◽  
Biological Response ◽  
Biologically Active Substances ◽  
Biologically Active ◽  
Alnus Incana ◽  
Fruit Extract ◽  
Antimicrobial Drugs ◽  
Resistance Development ◽  
Subinhibitory Concentrations ◽  
Active Substances

The emergence of microorganisms resistant strains is a natural biological response to the use of antimicrobial drugs that creates selective pressure, contributing to pathogens selection, survival and reproduction. The purpose of the investigation was to study the resistance development of staphylococci skin isolates to erythromycin and influence on it Alnus incana L. fruit extract subinhibitory concentrations. Development of resistance to erythromycin and influence on it Alnus incana L. fruit extract (extraction by 90% ethanol) subinhibitory concentrations were conducted with S epidermidis strains: sensitive and resistant to 14 and 15-membered macrolides. The study was carried out within 30 days by multiple consecutive passages of staphylococci test strains (concentration 1×107 CFU/ml) into test tubes containing broth and erythromycin ranging from 3 doubling dilutions above to doubling dilutions below the minimum inhibitory concentration. Statistical analysis of the results was carried out by one-and two-factor analysis of variance (ANOVA) and Microsoft Office Excel 2011. Rapid increase of resistance from 32 to 1024 μg/ml (F=34.2804; F> Fstand. max = 5.9874; p=0.0011) for S.epidermidis with a low level of resistance to 14 and 15-membered macrolides resistance to the erythromycine was observed. In the presence of Alnus incana L. fruit extract subinhibitory concentrations (¼ MIC), the initial MIC of erythromycin was decreased by 32 times to 1 μg/ml (F = 9.7497; F> Fstand. max = 5.9874; p = 0.0205). The sensitive strain after 30 passages did not develop resistance to erythromycin. Under the influence of erythromycin selective pressure, S.epidermidis strain with low initial level of MLS-resistance rapidly reaches a high-level resistance. Biologically active substances of the Alnus incana L. fruit extract significantly inhibit the resistance development in S. epidermidis to macrolides and eliminate it phenotypic features.

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