Hydrogen metabolism of Azospirillum brasilense in nitrogen-free medium

1980 ◽  
Vol 26 (9) ◽  
pp. 1126-1131 ◽  
Author(s):  
Y. K. Chan ◽  
L. M. Nelson ◽  
R. Knowles
Keyword(s):  
Gas Phase ◽  
Cyclic Gmp ◽  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Hydrogenase Activity ◽  
Similar Response ◽  
Uptake Hydrogenase ◽  
Hydrogen Metabolism ◽  
Free Medium ◽  
Batch Cultures

Production of H2 by Azospirillum brasilense under N2-fixing conditions was studied in continuous and batch cultures. Net H2 production was consistently observed only when the gas phase contained CO. Nitrogenase activity (C2H2 reduction) and H2 evolution (in the presence of 5% CO) showed a similar response to O2 and were highest at 0.75% dissolved O2. Uptake hydrogenase activity, ranging from 0.3 to 2.5 μmol H2/mg protein per hour was observed in batch cultures under N2. Such rates were more than sufficient to recycle nitrogenase-produced H2. Tritium-exchange assay showed that H2 uptake was higher under Ar than under N2. Uptake hydrogenase was strongly inhibited by CO and C2H2. Cyclic GMP inhibited both nitrogenase and uptake hydrogenase activities.

Effect of hydrogen and oxygen on uptake-hydrogenase activity in nitrogen-fixing and ammonium-grown Azospirillum brasilense

1983 ◽  
Vol 29 (9) ◽  
pp. 1119-1125 ◽  
Author(s):  
Karl H. Tibelius ◽  
Roger Knowles
Keyword(s):  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Hydrogen Uptake ◽  
Rapid Decline ◽  
Hydrogenase Activity ◽  
Uptake Hydrogenase ◽  
Batch Cultures ◽  
Whole Cells ◽  
Irreversible Inhibition ◽  
Microaerobic Conditions

Hydrogen uptake by Azospirillum brasilense was studied in N2-fixing and NH4Cl-grown batch cultures. The Km for H2 of uptake hydrogenase (O2-dependent H3H uptake) in whole cells was 9 µM. In N2-flxing or NH4Cl-grown cultures hydrogenase activity reached its maximum in late log phase, followed by a rapid decline in stationary phase. In cultures sparged with H2, hydrogenase activity was markedly prolonged. Rates of O2-dependent H3H uptake and H2 uptake measured by gas chromatography were very similar. Hydrogenase derepression required microaerobic conditions, was independent of nitrogenase derepression, did not require exogenous H2, and may be enhanced by electron-donor limitation. Air caused irreversible inhibition of hydrogenase activity. In N-free cultures, theO2 optima for H2 uptake, ranging from 0.5 to 1.25% O2 depending on the phase of growth, were significantly higher than those for nitrogenase activity (C2H2 reduction), 0.15 to 0.35%, suggesting that H2 uptake may have a limited ability to aid in the protection of nitrogenase against inactivation by O2.

scholarly journals Measurement in vivo of hydrogenase-catalysed hydrogen evolution in the presence of nitrogenase enzyme in cyanobacteria

1979 ◽  
Vol 177 (1) ◽  
pp. 139-144 ◽  
Author(s):  
A Daday ◽  
G R Lambert ◽  
G D Smith
Keyword(s):  
Gas Phase ◽  
Methyl Viologen ◽  
Nitrogenase Activity ◽  
Conclusive Evidence ◽  
Hydrogenase Activity ◽  
H2 Evolution ◽  
Total Inhibition ◽  
Low Concentrations ◽  
Cyanobacterium Anabaena

A method was devised that allows measurement in vivo of hydrogenase-catalysed H2 evolution from the cyanobacterium Anabaena cylindrica, independent of nitrogenase activity, which is also present. Addition of low concentrations of reduced Methyl Viologen (1-10mM) to intact heterocystous filaments of the organism resulted in H2 evolution, but produced conditions giving total inhibition of nitrogenase (acetylene-reducing and H2-evolving) activity. That the H2 formed under these conditions was not contributed to by nitrogenase was also supported by the observation that its rate of formation was similar in the dark or with Ar replaced by N2 in the gas phase, and also in view of the pattern of H2 evolution at very low Methyl Viologen concentrations. Conclusive evidence that the H2 formed in the presence of Methyl Viologen was solely hydrogenase-mediated was its evolution even from nitrogenase-free (non-heterocystous) cultures; by contrast ‘uptake’ hydrogenase activity in such cultures was greatly decreased. The hydrogenase activity was inhibited by CO and little affected by acetylene. Finally the hydrogenase activity was shown to be relatively constant at different stages during the batch growth of the organism, as opposed to nitrogenase activity, which varied.

scholarly journals Hydrogen-uptake Hydrogenase Activity in Nitrogen-fixing Azospirillum brasilense

Microbiology ◽  
1982 ◽  
Vol 128 (1) ◽  
pp. 161-166
Author(s):  
F. O. PEDROSA ◽  
M. STEPHAN ◽  
J. DOBEREINER ◽  
M. G. YATES
Keyword(s):  
Azospirillum Brasilense ◽  
Hydrogen Uptake ◽  
Hydrogenase Activity ◽  
Uptake Hydrogenase ◽  
Nitrogen Fixing

Biphasic nitrogenase activity in Azospirillum brasilense in long lasting batch cultures

1980 ◽  
Vol 128 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Hans Papen ◽  
Dietrich Werner
Keyword(s):  
Azospirillum Brasilense ◽  
Nitrogenase Activity ◽  
Batch Cultures

Pisum sativum cultivar effects on hydrogen metabolism in Rhizobium

1984 ◽  
Vol 62 (8) ◽  
pp. 1682-1686 ◽  
Author(s):  
Eulogio J. Bedmar ◽  
Donald A. Phillips
Keyword(s):  
Pisum Sativum ◽  
Relative Efficiency ◽  
Rhizobium Leguminosarum ◽  
Root Nodules ◽  
Developmental Differences ◽  
The Other ◽  
Hydrogenase Activity ◽  
Uptake Hydrogenase ◽  
Hydrogen Metabolism ◽  
Pisum Sativum L

Data from 14 Pisum sativum L. cultivars establish that three pea genotypes, which were previously reported to affect net H2 evolution from root nodules in air and uptake hydrogenase activity of Rhizobium leguminosarum 128C53, are not unique. Two pea lines, 'JI1205' and 'Green Arrow,' produced very active uptake hydrogenase activity in strain 128C53, and essentially no H2 was evolved in air from root nodules capable of reducing 20 μmol C2H2 ∙ plan−1 ∙ h−1. Five other cultivars produced significantly lower uptake hydrogenase activities in the same bacterial strain and had much higher rates of net H2 evolution with similar C2H2-reduction capabilities. Parallel experiments with the same cultivars nodulated by R. leguminosarum 300, an organism with no convincing uptake hydrogenase activity in any pea line, showed that 'JI1205' and 'Green Arrow' had a significantly lower relative efficiency (RE) of N2 fixation (1 − (H2 evolved in air/C2H2 reduced)) than the other five cultivars. Developmental differences among the pea lines prevented any conclusion about the advantages or disadvantages of uptake hydrogenase activity for plant growth, but in general, cultivars with high uptake hydrogenase activity and low net H2 evolution grew more slowly than those evolving large amounts of H2.

scholarly journals Hydrogen Photoproduction by Immobilized N2-Fixing Cyanobacteria: Understanding the Role of the Uptake Hydrogenase in the Long-Term Process

2014 ◽  
Vol 80 (18) ◽  
pp. 5807-5817 ◽  
Author(s):  
Sergey Kosourov ◽  
Hannu Leino ◽  
Gayathri Murukesan ◽  
Fiona Lynch ◽  
Kaarina Sivonen ◽  
...  
Keyword(s):  
Photosynthetic Activity ◽  
Nitrogenase Activity ◽  
Photosynthetic Apparatus ◽  
Hydrogenase Activity ◽  
Uptake Hydrogenase ◽  
Wild Type ◽  
Vegetative Cells ◽  
Content Type ◽  
N Deficiency ◽  
Pcc 7120

ABSTRACTWe have investigated two approaches to enhance and extend H2photoproduction yields in heterocystous, N2-fixing cyanobacteria entrapped in thin alginate films. In the first approach, periodic CO2supplementation was provided to alginate-entrapped, N-deprived cells. N deprivation led to the inhibition of photosynthetic activity in vegetative cells and the attenuation of H2production over time. Our results demonstrated that alginate-entrapped ΔhupLcells were considerably more sensitive to high light intensity, N deficiency, and imbalances in C/N ratios than wild-type cells. In the second approach,Anabaenastrain PCC 7120, its ΔhupLmutant, andCalothrixstrain 336/3 films were supplemented with N2by periodic treatments of air, or air plus CO2. These treatments restored the photosynthetic activity of the cells and led to a high level of H2production inCalothrix336/3 and ΔhupLcells (except for the treatment air plus CO2) but not in theAnabaenaPCC 7120 strain (for which H2yields did not change after air treatments). The highest H2yield was obtained by the air treatment of ΔhupLcells. Notably, the supplementation of CO2under an air atmosphere led to prominent symptoms of N deficiency in the ΔhupLstrain but not in the wild-type strain. We propose that uptake hydrogenase activity in heterocystous cyanobacteria not only supports nitrogenase activity by removing excess O2from heterocysts but also indirectly protects the photosynthetic apparatus of vegetative cells from photoinhibition, especially under stressful conditions that cause an imbalance in the C/N ratio in cells.

Nitrogen fixation and hydrogen metabolism by Rhizobium leguminosarum isolates in pea root nodules

1981 ◽  
Vol 27 (10) ◽  
pp. 1028-1034 ◽  
Author(s):  
Louise M. Nelson ◽  
J. J. Child
Keyword(s):  
Relative Efficiency ◽  
Rhizobium Leguminosarum ◽  
High Efficiency ◽  
Root Nodules ◽  
Dry Weight ◽  
Hydrogenase Activity ◽  
Uptake Hydrogenase ◽  
Hydrogen Metabolism ◽  
N Content ◽  
Significant Uptake

A survey of 108 isolates of Rhizobium leguminosarum was conducted to determine the variation in H2 uptake and relative efficiency of N2 fixation in Pisum sativum L. root nodules and the relation of relative efficiency to plant dry weight and N content. Only 14 of the isolates exhibited significant uptake hydrogenase activity and none of these had sufficient hydrogenase activity to recycle all of the H2 produced by nitrogenase. In 74 of the isolates tested relative efficiencies of N2 fixation were less than 0.60.Twenty-nine of the isolates were ineffective, since total plant N at harvest did not differ significantly from uninoculated controls. The remaining 79 effective isolates could be divided into low-and high-efficiency groups. Plants which were inoculated with isolates from the two groups and harvested after 4 weeks did not differ significantly in plant dry weight or N content. Among the isolates with high relative efficiency of N2 fixation, two groups could be recognized: one possessing significant uptake hydrogenase activity, the other lacking hydrogenase activity but in which H2 evolution was low. Although the two groups did not differ with respect to plant dry weight or N content, the identification of this latter group may be of some significance for optimizing the efficiency of N2 fixation.

Molybdenum incorporation in denitrifying Azospirillum brasilense Sp7

1992 ◽  
Vol 38 (10) ◽  
pp. 1042-1047 ◽  
Author(s):  
Christian Chauret ◽  
Wilfredo L. Barraquio ◽  
Roger Knowles
Keyword(s):  
Nitrate Reductase ◽  
Key Words ◽  
Nitrate Reduction ◽  
Gel Electrophoresis ◽  
Azospirillum Brasilense ◽  
Paracoccus Denitrificans ◽  
Free Medium ◽  
Azospirillum Brasilense Sp7

Nondenaturating disc gel electrophoresis revealed that 99Mo was incorporated into the nitrate reductase of Azospirillum brasilense grown in the absence but not in the presence of tungstate. Under denitrifying conditions, A. brasilense grown in tungsten-free medium steadily accumulated 99Mo for 12 h. In contrast, Paracoccus denitrificans grown under the same conditions ceased uptake after 1 h. However, both bacteria were incapable of accumulating significant amounts of 99Mo in media containing 10 mM tungstate, even though nitrate was reduced by A. brasilense. Aerobically grown A. brasilense cells transported 99Mo more efficiently than anaerobically grown cells. Key words: Azospirillum brasilense, tungsten, molybdenum incorporation, nitrate reduction.

How Does the DraG-PIIComplex Regulate Nitrogenase Activity in Azospirillum brasilense?

2015 ◽  
pp. 139-146 ◽  
Author(s):  
Xiao-Dan Li ◽  
Fritz K. Winkler ◽  
Luciano F. Huergo
Keyword(s):  
Azospirillum Brasilense ◽  
Nitrogenase Activity
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