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.

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.

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

scholarly journals Hydrogen-Oxidizing Capabilities of Helicobacter hepaticus and In Vivo Availability of the Substrate

2003 ◽  
Vol 185 (8) ◽  
pp. 2680-2682 ◽  
Author(s):  
Robert J. Maier ◽  
Jonathan Olson ◽  
Adriana Olczak
Keyword(s):  
Hydrogen Uptake ◽  
Host Tissue ◽  
Hydrogenase Activity ◽  
Helicobacter Hepaticus ◽  
Reductive Activation ◽  
Respiratory Pathway ◽  
Positive Potential ◽  
Whole Cells ◽  
Microelectrode Measurements

ABSTRACT Hydrogen-oxidizing hydrogenase activity was detected in Helicobacter hepaticus and compared to the activity in Helicobacter pylori for characteristics associated with hydrogen uptake respiratory hydrogenases. Intact whole cells could couple H2 oxidation to oxygen uptake, and no H2 uptake was observed without oxygen available to complete the respiratory pathway. The H. hepaticus enzyme coupled H2 oxidation to reduction of many positive potential acceptors, and it underwent anaerobic or reductive activation. H. hepaticus had a strong affinity for molecular H2 (apparent Km of 2.5 μM), and microelectrode measurements on the livers of live mice demonstrated that H2 is available in the host tissue at levels 20-fold greater than the apparent whole-cell Km value.

Hydrogenase in Frankia KB5: Expression of and relation to nitrogenase

2000 ◽  
Vol 46 (12) ◽  
pp. 1091-1095 ◽  
Author(s):  
Ulrika Mattsson ◽  
Anita Sellstedt
Keyword(s):  
Nitrogenase Activity ◽  
Large Subunit ◽  
Hydrogen Uptake ◽  
Hydrogenase Activity ◽  
Free Living ◽  
Monitoring Activity

The localization and expression of the hydrogenase in free-living Frankia KB5 was investigated immunologically and by monitoring activity, focusing on its relationships with nitrogenase and H2. Immunological studies revealed that the large subunit of the hydrogenase in Frankia KB5 was modified post-translationally, and transferred into the membrane after processing. The large subunit was constitutively expressed and no correlation was found between hydrogenase activity and synthesis. Although H2 was not needed for induction of hydrogenase synthesis, exogenously added H2 triggered hydrogen uptake in medium containing nitrogen, i.e., in the hyphae. A correlation between nitrogenase activity and hydrogen uptake was found in cultures grown in media without nitrogen, but interestingly the two enzymes showed no co-regulation.Key words: hydrogenase, expression, nitrogenase, Frankia KB5.

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.

scholarly journals EVALUATION OF HUP+, HUP– AND A TRANSCONJUGANT RHIZOBIUM ON YIELD, NITROGEN FIXATION, AND UPTAKE HYDROGENASE ACTIVITY IN SELECTED CHICKPEA CULTIVARS

HortScience ◽  
1996 ◽  
Vol 31 (3) ◽  
pp. 324e-324
Author(s):  
G.M. Sajid ◽  
W.F. Campbell
Keyword(s):  
Root Nodules ◽  
Hydrogen Uptake ◽  
Hydrogen Gas ◽  
Acetylene Reduction Activity ◽  
Hydrogenase Activity ◽  
Uptake Hydrogenase ◽  
Higher Plant ◽  
Reduction Activity ◽  
Uptake Activity ◽  
Plant Yields

Evolution of hydrogen gas (H2) during N2 reduction in root nodules results in inefficient use of energy needed for N2 fixation. Cultivars of chickpea (Cicer arietinum L.) were inoculated with Rhizobium strains with and without genes for uptake hydrogenase (Hup) activity. H2 evolution, acetylene reduction activity, and uptake hydrogenase (Hup) activity were assayed on the resulting nodules. The Hup– strains produced higher plant yields than the Hup+ strains. The +N controls produced significantly higher yields than the –N controls and plants inoculated with Rhizobium strains. Hydrogen uptake activity by Rhizobium strains was influenced by the cultivar characteristics. Expression of the plasmid-borne hup genes (pHU52) of Bradyrhizobium japonicum was modified by the host cultivar. The average nodule fresh weight and shoot and root dry weights of the cultivars significantly increased following inoculation with the transconjugant Hup+ Rhizobium strain. Thus, biological N2 fixation may be enhanced by selecting Rhizobium strains that are appropriately matched to the particular cultivar. Incorporation of transconjugant Hup+ genes can increase rhizobial activity.

Sign in / Sign up

Export Citation Format

Share Document