Effect of an increasing carbon: nitrate-N ratio on the reliability of acetylene in blocking the N2O-reductase activity of denitrifying bacteria in soil

Diploid sugar beet was grown in controlled environment at 25/17 deg C in 14-h photoperiods in well aerated, regularly changed nutrient solution containing 6 meq NO3/l. When 6 leaves had been expanded, the total carboxylate content of the oldest leaf (leaf 1) was found to be 5836 meq/kg DM, while that of leaf 6 was only 2312 meq/kg; the difference was mainly due to oxalate content, which was 5236 meq/kg in leaf 1 and 1744 meq/kg in leaf 6. Nitrate-N content was about 50% higher in leaf 1 than in leaf 4. Nitrate-reductase activity fell to very low values as leaves aged. Experiments in which young and old leaf material was mixed, or oxalate at 0-4000 meq/kg DM was added to leaf samples, showed that oxalate had no substantial effect on nitrate-reductase activity. (Abstract retrieved from CAB Abstracts by CABI’s permission)

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Linked Expressions ofnapandnosGenes in a Bradyrhizobium japonicum Mutant with Increased N2O Reductase Activity

Applied and Environmental Microbiology ◽

10.1128/aem.00703-13 ◽

2013 ◽

Vol 79 (13) ◽

pp. 4178-4180 ◽

Cited By ~ 8

Author(s):

Cristina Sánchez ◽

Manabu Itakura ◽

Hisayuki Mitsui ◽

Kiwamu Minamisawa

Keyword(s):

Nitrate Reductase ◽

Bradyrhizobium Japonicum ◽

Enrichment Culture ◽

Reductase Activity ◽

Content Type ◽

Periplasmic Nitrate Reductase ◽

Expression Of Genes ◽

Genes Encoding ◽

N2o Reductase

ABSTRACTTo understand the mechanisms underlying the increased N2O reductase activity in theBradyrhizobium japonicum5M09 mutant from enrichment culture under N2O respiration, we analyzed the expression of genes encoding denitrification reductases and regulators. Our results suggest a common regulation ofnap(encoding periplasmic nitrate reductase) andnos(encoding N2O reductase).

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A One-Hole Cu4S Cluster with N2O Reductase Activity: A Structural and Functional Model for CuZ*

Journal of the American Chemical Society ◽

10.1021/jacs.6b05480 ◽

2016 ◽

Vol 138 (40) ◽

pp. 13107-13110 ◽

Cited By ~ 21

Author(s):

Brittany J. Johnson ◽

William E. Antholine ◽

Sergey V. Lindeman ◽

Michael J. Graham ◽

Neal P. Mankad

Keyword(s):

Reductase Activity ◽

Functional Model ◽

N2o Reductase

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Generation of Bradyrhizobium japonicum Mutants with Increased N2O Reductase Activity by Selection after Introduction of a Mutated dnaQ Gene

Applied and Environmental Microbiology ◽

10.1128/aem.01850-08 ◽

2008 ◽

Vol 74 (23) ◽

pp. 7258-7264 ◽

Cited By ~ 19

Author(s):

Manabu Itakura ◽

Kazufumi Tabata ◽

Shima Eda ◽

Hisayuki Mitsui ◽

Kiriko Murakami ◽

...

Keyword(s):

Nitrogen Fixation ◽

Bradyrhizobium Japonicum ◽

Symbiotic Nitrogen Fixation ◽

Enrichment Culture ◽

Reductase Activity ◽

Wild Type ◽

Epsilon Subunit ◽

Bacterial Mutants ◽

N2o Reductase ◽

Type Strains

ABSTRACT We obtained two beneficial mutants of Bradyrhizobium japonicum USDA110 with increased nitrous oxide (N2O) reductase (N2OR) activity by introducing a plasmid containing a mutated B. japonicum dnaQ gene (pKQ2) and performing enrichment culture under selection pressure for N2O respiration. Mutation of dnaQ, which encodes the epsilon subunit of DNA polymerase III, gives a strong mutator phenotype in Escherichia coli. pKQ2 introduction into B. japonicum USDA110 increased the frequency of occurrence of colonies spontaneously resistant to kanamycin. A series of repeated cultivations of USDA110 with and without pKQ2 was conducted in anaerobic conditions under 5% (vol/vol) or 20% (vol/vol) N2O atmosphere. At the 10th cultivation cycle, cell populations of USDA110(pKQ2) showed higher N2OR activity than the wild-type strains. Four bacterial mutants lacking pKQ2 obtained by plant passage showed 7 to 12 times the N2OR activity of the wild-type USDA110. Although two mutants had a weak or null fix phenotype for symbiotic nitrogen fixation, the remaining two (5M09 and 5M14) had the same symbiotic nitrogen fixation ability and heterotrophic growth in culture as wild-type USDA110.

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Loss of N2O reductase activity as an explanation for poor growth of Pseudomonas aeruginosa on N2O.

Applied and Environmental Microbiology ◽

10.1128/aem.53.9.2045-2049.1987 ◽

1987 ◽

Vol 53 (9) ◽

pp. 2045-2049 ◽

Cited By ~ 13

Author(s):

S W Snyder ◽

D A Bazylinski ◽

T C Hollocher

Keyword(s):

Pseudomonas Aeruginosa ◽

Reductase Activity ◽

Poor Growth ◽

N2o Reductase

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Ecological and physiological implications of nitrogen oxide reduction pathways on greenhouse gas emissions in agroecosystems

FEMS Microbiology Ecology ◽

10.1093/femsec/fiz066 ◽

2019 ◽

Vol 95 (6) ◽

Cited By ~ 10

Author(s):

Sukhwan Yoon ◽

Bongkeun Song ◽

Rebecca L Phillips ◽

Jin Chang ◽

Min Joon Song

Keyword(s):

Reductase Activity ◽

Ghg Emissions ◽

Mitigation Strategies ◽

N2o Emissions ◽

Oxide Reduction ◽

N Budget ◽

Ghg Mitigation ◽

N Losses ◽

N2o Production ◽

N2o Reductase

ABSTRACT Microbial reductive pathways of nitrogen (N) oxides are highly relevant to net emissions of greenhouse gases (GHG) from agroecosystems. Several biotic and abiotic N-oxide reductive pathways influence the N budget and net GHG production in soil. This review summarizes the recent findings of N-oxide reduction pathways and their implications to GHG emissions in agroecosystems and proposes several mitigation strategies. Denitrification is the primary N-oxide reductive pathway that results in direct N2O emissions and fixed N losses, which add to the net carbon footprint. We highlight how dissimilatory nitrate reduction to ammonium (DNRA), an alternative N-oxide reduction pathway, may be used to reduce N2O production and N losses via denitrification. Implications of nosZ abundance and diversity and expressed N2O reductase activity to soil N2O emissions are reviewed with focus on the role of the N2O-reducers as an important N2O sink. Non-prokaryotic N2O sources, e.g. fungal denitrification, codenitrification and chemodenitrification, are also summarized to emphasize their potential significance as modulators of soil N2O emissions. Through the extensive review of these recent scientific advancements, this study posits opportunities for GHG mitigation through manipulation of microbial N-oxide reductive pathways in soil.

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