scholarly journals Symbiotic Bradyrhizobium japonicum Reduces N2O Surrounding the Soybean Root System via Nitrous Oxide Reductase

2006 ◽  
Vol 72 (4) ◽  
pp. 2526-2532 ◽  
Author(s):  
Reiko Sameshima-Saito ◽  
Kaori Chiba ◽  
Junta Hirayama ◽  
Manabu Itakura ◽  
Hisayuki Mitsui ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Root System ◽  
Bradyrhizobium Japonicum ◽  
Reductase Activity ◽  
Ambient Air ◽  
Living Cells ◽  
Nitrous Oxide Reductase ◽  
Free Living ◽  
Low Concentrations ◽  
Soybean Roots

ABSTRACT N2O reductase activity in soybean nodules formed with Bradyrhizobium japonicum was evaluated from N2O uptake and conversion of 15N-N2O into 15N-N2. Free-living cells of USDA110 showed N2O reductase activity, whereas a nosZ mutant did not. Complementation of the nosZ mutant with two cosmids containing the nosRZDFYLX genes of B. japonicum USDA110 restored the N2O reductase activity. When detached soybean nodules formed with USDA110 were fed with 15N-N2O, they rapidly emitted 15N-N2 outside the nodules at a ratio of 98.5% of 15N-N2O uptake, but nodules inoculated with the nosZ mutant did not. Surprisingly, N2O uptake by soybean roots nodulated with USDA110 was observed even in ambient air containing a low concentration of N2O (0.34 ppm). These results indicate that the conversion of N2O to N2 depends exclusively on the respiratory N2O reductase and that soybean roots nodulated with B. japonicum carrying the nos genes are able to remove very low concentrations of N2O.

Temporary low oxygen conditions for the formation of nitrate reductase and nitrous oxide reductase by denitrifying Pseudomonas sp. G59

1986 ◽  
Vol 32 (7) ◽  
pp. 543-547 ◽  
Author(s):  
Tokujiro Aida ◽  
Shyuichi Hata ◽  
Haruo Kusunoki
Keyword(s):  
Nitrous Oxide ◽  
Nitrate Reductase ◽  
Major Product ◽  
Nitrous Oxide Reductase ◽  
Pseudomonas Sp ◽  
Low Oxygen ◽  
Respiratory Enzymes ◽  
Low Concentrations ◽  
Oxygen Conditions ◽  
Microaerobic Conditions

Formation of nitrate reductase (NaR) and nitrous oxide reductase (N2OR) by a Pseudomonas sp. G59 did not occur in aerobic or anaerobic conditions, but was observed in a microaerobic incubation in which an anaerobically grown culture was agitated in a sealed vessel initially containing 20 kPa oxygen in the headspace. During the microaerobic incubation, the oxygen concentration in the headspace decreased and dissolved oxygen reached 0.1–0.2 kPa. NaR activity was detected immediately and N2OR activity after 3 h of incubation irrespective of the presence or absence of NO3− or N2O. In the presence of NO3−, NO2− was accumulated as a major product, but N2O was observed in low concentrations only after N2OR appeared. After microaerobic incubation for 3 h, N2OR formation continued even anaerobically in an atmosphere of N2O. In contrast, Escherichia coli formed NaR not only microaerobically but also anaerobically. However, NaR formation by E. coli was inhibited by sodium fluoride under anaerobic, but not under microaerobic conditions. The Pseudomonas culture did not possess fermentative activity. It is suggested that the dependence on microaerobiosis for the formation of these reductases by the Pseudomonas culture was due to an inability to produce energy anaerobically until these anaerobic respiratory enzymes were formed.

Differentiation of Rhizobium japonicum, I. Enzymatic Comparison of Nitrogenase Repressed and Derepressed Free Living Cells and of Bacteroids

1978 ◽  
Vol 33 (3-4) ◽  
pp. 245-252 ◽  
Author(s):  
D. Werner ◽  
R. Stripf
Keyword(s):  
Gas Phase ◽  
Liquid Culture ◽  
Nitrogenase Activity ◽  
Living Cells ◽  
Maximum Activity ◽  
Rhizobium Japonicum ◽  
Free Living ◽  
Low Concentrations ◽  
Specific Activities ◽  
Japonicum Strain

Derepressed free living cells of Rhizobium japonicum strain 61-A-101 with leucine as single nitrogen source develop a maximum nitrogenase activity of 180 nmol C2H4 · mg protein -1·h-1 in liquid culture under 2% O2 in the gas phase. Only 10% of this activity is found with no oxygen in the gas phase during a 90 min incubation period. The maximum activity under 2% oxygen in the gas phase is unaffected by addition of 1 -100 mM NH4* and by addition of low concentrations of glutamine (0.36 - 1.44 mᴍ).Specific activities of alanine dehydrogenase (E.C. 1.4.1.1.) aspartate aminotransferase (E.C. 2.6.1.1.) and, with much lower activities, of GOGAT (E.C. 1.4.1.13) in nitrogenase active free living cells are more similar to bacteroids than to nitrogenase repressed free living cells from liquid culture. The activities in nitrogenase repressed cells were about 50% lower. Glutamine synthetase (E.C. 6.3.1.2.) activity in bacteroids and in nitrogenase active cells were also similar, but only about 25 - 30% of that found in nitrogenase repressed Rhizobium japonicum cells.

The multicopper oxidase from the archaeon Pyrobaculum aerophilum shows nitrous oxide reductase activity

FEBS Journal ◽  
2010 ◽  
Vol 277 (15) ◽  
pp. 3176-3189 ◽  
Author(s):  
André T. Fernandes ◽  
João M. Damas ◽  
Smilja Todorovic ◽  
Robert Huber ◽  
M. Camilla Baratto ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Reductase Activity ◽  
Multicopper Oxidase ◽  
Nitrous Oxide Reductase ◽  
Pyrobaculum Aerophilum

The expression of nitrate reductase in free-living Rhizobium sp.

1984 ◽  
Vol 30 (7) ◽  
pp. 890-893 ◽  
Author(s):  
Rachel Gollop ◽  
Yael J. Avissar
Keyword(s):  
Enzyme Activity ◽  
Nitrate Reductase ◽  
Nitrate Reductase Activity ◽  
Reductase Activity ◽  
Living Cells ◽  
Early Stationary Phase ◽  
Free Living ◽  
Rhizobium Sp ◽  
Stationary Cell

Nitrate reductase activity is expressed in bacteroids of peanut nodules but is absent in log phase cultures of Rhizobium sp. grown in the absence of nitrate. The assay of enzyme activity in free-living cells in vivo revealed a brief period of activity in early stationary phase and a recovery of activity upon prolonged microaerobic incubation of stationary cell suspensions. The expression of enzyme activity did not necessitate concurrent differentiation of rhizobia to bacteriods or the induction of nitrogenase.

Molecular characterization of nosRZDFYLX genes coding for denitrifying nitrous oxide reductase of Bradyrhizobium japonicum

2004 ◽  
Vol 85 (3) ◽  
pp. 229-235 ◽  
Author(s):  
Leonardo Velasco ◽  
Socorro Mesa ◽  
Chang-ai Xu ◽  
María J. Delgado ◽  
Eulogio J. Bedmar
Keyword(s):  
Nitrous Oxide ◽  
Molecular Characterization ◽  
Bradyrhizobium Japonicum ◽  
Nitrous Oxide Reductase

Malonate and Krebs Cycle Intermediates Utilization in the Presence of other Carbon Sources by Rhizobium japonicum and Soybean Bacteroids

1982 ◽  
Vol 37 (10) ◽  
pp. 921-926 ◽  
Author(s):  
Dietrich Werner ◽  
Walburga Dittrich ◽  
Heidemarie Thierfelder
Keyword(s):  
Sole Carbon Source ◽  
Carbon Sources ◽  
Krebs Cycle ◽  
Living Cells ◽  
The Other ◽  
Rhizobium Japonicum ◽  
Free Living ◽  
Low Concentrations ◽  
Substrate Saturation ◽  
Krebs Cycle Intermediates

Abstract Free living cells of Rhizobium japonicum 61-A-101 and bacteroids from Glycine max var. Mandarin infected with the same strain utilized malonate with a substrate saturation greater than 10-2 mol/l. At low concentrations of malonate (10-5 mol/1) the free living cells were significantly more active in utilizing malonate than bacteroids. In bacteroids two substrate saturation ranges were found, one between 3 x 10-4mol/l and 10-3 mol/l, the other at more than 10-2 mol/l. Utilization of malonate was not affected by 10 to 100 times larger concentrations of either arabinose or xylose. 10-3 mol/l succinate inhibited the utilization of malonate (10-4 mol/l) completely in bacteroids, and by 90% in free living cells. Succinate utilization (10-4 mol/1) was reduced in those cells exposed to 100 times higher malonate concentration only by 20-30% . Utilization and incorporation of pyruvate and 2-oxoglutarate into bacteroids was also only slightly affected by 100 times larger malonate concentration. Citrate utilization by bacteroids however was reduced by more than 70%. The rate of endoxidation of malonate as sole carbon source (14CO2 production from [2-14C] malonic acid)was about 1.5 μmol · h-1 • mg protein-1 and about half the rate with Pseudomonas putida and 70% o f the rate with Pseudomonas fluorescens under the same conditions (pH 6.0, 28 °C).

scholarly journals Functional characterization of the Bradyrhizobium japonicum modA and modB genes involved in molybdenum transport

Microbiology ◽  
2006 ◽  
Vol 152 (1) ◽  
pp. 199-207 ◽  
Author(s):  
María J. Delgado ◽  
Alvaro Tresierra-Ayala ◽  
Chouhra Talbi ◽  
Eulogio J. Bedmar
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Reductase Activity ◽  
Functional Characterization ◽  
Symbiotic Association ◽  
Free Living ◽  
Mineral Solution ◽  
Wild Type Phenotype ◽  
Mutant Strains ◽  
Soybean Plants

A modABC gene cluster that encodes an ABC-type, high-affinity molybdate transporter from Bradyrhizobium japonicum has been isolated and characterized. B. japonicum modA and modB mutant strains were unable to grow aerobically or anaerobically with nitrate as nitrogen source or as respiratory substrate, respectively, and lacked nitrate reductase activity. The nitrogen-fixing ability of the mod mutants in symbiotic association with soybean plants grown in a Mo-deficient mineral solution was severely impaired. Addition of molybdate to the bacterial growth medium or to the plant mineral solution fully restored the wild-type phenotype. Because the amount of molybdate required for suppression of the mutant phenotype either under free-living or under symbiotic conditions was dependent on sulphate concentration, it is likely that a sulphate transporter is also involved in Mo uptake in B. japonicum. The promoter region of the modABC genes has been characterized by primer extension. Reverse transcription and expression of a transcriptional fusion, PmodA–lacZ, was detected only in a B. japonicum modA mutant grown in a medium without molybdate supplementation. These findings indicate that transcription of the B. japonicum modABC genes is repressed by molybdate.

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