Nitrogen Fixation, a Molybdenum-Requiring Process

Presta, Luana; Fondi, Marco; Emiliani, Giovanni; Fani, Renato

doi:10.1007/978-94-017-9972-0_5

Cited by 3 publications

(7 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…After exposure to MoO 4 2– , N 2 -fixation capacity as measured by both expression level of nifH and nitrogenase activity increased sharply by 27- and 2.2-fold, respectively, compared to the control (WT + PCB) (Figure A). This result is consistent with previous findings of rapid nitrogenase response to MoO 4 2– in both symbiotic and free-living species ,, and reflects that Mo is part of the primary cofactor required for nitrogenase activity. − Consistent with previous reports, , addition of reactive nitrogen (NO 2 – and NO 3 – ) significantly suppressed nitrogenase transcription and activity ( P < 0.05), with 39–46% and 49–100% decreases below control levels (WT + PCB), respectively. To further manipulate nitrogenase levels, a mutant was constructed in the gene nifA , a transcriptional activator of nifHDK .…”

Section: Results and Discussionsupporting

confidence: 92%

“…After exposure to MoO 4 2− , N 2fixation capacity as measured by both expression level of nif H and nitrogenase activity increased sharply by 27-and 2.2-fold, respectively, compared to the control (WT + PCB) (Figure 1A). This result is consistent with previous findings of rapid nitrogenase response to MoO 4 2− in both symbiotic and freeliving species 24,25,32 and reflects that Mo is part of the primary cofactor required for nitrogenase activity. 24−26 Consistent with previous reports, 22,23 addition of reactive nitrogen (NO 2 − and NO 3…”

Section: Methodssupporting

confidence: 93%

“…It should be noted that Mo participates in a range of biochemical processes in addition to nitrogen fixation. Most notably, it serves as a cofactor in enzymes involved in the denitrification and nitrogen assimilation (i.e., nitrate reductase, NaR) 25 and several studies suggest that NaR activity in crude microbial and plant extracts enhances the dechlorination of organohalides. 34,35 However, contrary to these reports, our data show that supplemental NO 3 − , the substrate of NaR, significantly suppresses rhizobial dechlorination in intact plants.…”

contrasting

confidence: 99%

“…To evaluate the interaction between nitrogenase activity and rhizobial transformation of PCB 77 within nodules, 50 day-old plants with mature nodules (inoculation with strain WT) were watered with different chemical treatments. Reactive N (10 mmol L –1 KNO 3 and KNO 2 ) was supplied to suppress N 2 fixation, , while 0.25 mmol L –1 Na 2 MoO 4 (a readily soluble form of molybdate) was used to enhance nitrogenase activity. − On the basis of our preliminary experiments and previously published work, treatments with nitrogenase inhibitors or stimulants led to significant changes in nitrogenase activities within 2 to 7 days. ,, Thus, plants were harvested 5 days after exposure to nitrogenase inhibitors or stimulant. PCB-supplemented seedlings treated with sterile distilled water were used as blank controls.…”

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium–Legume Symbiosis

Wang

Teng

et al. 2018

Environ. Sci. Technol.

View full text Add to dashboard Cite

Legume-rhizobium symbioses have the potential to remediate soils contaminated with chlorinated organic compounds. Here, the model symbiosis between Medicago sativa and Sinorhizobium meliloti was used to explore the relationships between symbiotic nitrogen fixation and transformation of tetrachlorobiphenyl PCB 77 within this association. 45-day-old seedlings in vermiculite were pretreated with 5 mg L PCB 77 for 5 days. In PCB-supplemented nodules, addition of the nitrogenase enhancer molybdate significantly stimulated dechlorination by 7.2-fold and reduced tissue accumulation of PCB 77 (roots by 96% and nodules by 93%). Conversely, dechlorination decreased in plants exposed to a nitrogenase inhibitor (nitrate) or harboring nitrogenase-deficient symbionts (nifA mutant) by 29% and 72%, respectively. A range of dechlorinated products (biphenyl, methylbiphenyls, hydroxylbiphenyls, and trichlorobiphenyl derivatives) were detected within nodules and roots under nitrogen-fixing conditions. Levels of nitrogenase-derived hydrogen and leghemoglobin expression correlated positively with nodular dechlorination rates, suggesting a more reducing environment promotes PCB dechlorination. Our findings demonstrate for the first time that symbiotic nitrogen fixation acts as a driving force for tetrachlorobiphenyl dechlorination. In turn, this opens new possibilities for using rhizobia to enhance phytoremediation of halogenated organic compounds.

show abstract

Section: Results and Discussionsupporting

confidence: 92%

Section: Methodssupporting

confidence: 93%

contrasting

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 2 more Smart Citations

Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium–Legume Symbiosis

Wang

Teng

et al. 2018

Environ. Sci. Technol.

View full text Add to dashboard Cite

show abstract

“…The species K. pneumoniae has been reported with the ability of nitrogen fixation in nature (2, 3). We isolated Klebsiella sp.…”

Section: Genome Announcementmentioning

confidence: 99%

Draft Genome Sequence of Klebsiella sp. Strain C31 Isolated from a Malaysian Tropical Peat Swamp Forest

et al. 2018

View full text Add to dashboard Cite

show abstract

Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life

2024

View full text Add to dashboard Cite

Venus is Earth's sister planet, with similar mass and density but an uninhabitably hot surface, an atmosphere with a water activity 50-100 times lower than anywhere on Earths' surface, and clouds believed to be made of concentrated sulfuric acid. These features have been taken to imply that the chances of finding life on Venus are vanishingly small, with several authors describing Venus' clouds as ''uninhabitable,'' and that apparent signs of life there must therefore be abiotic, or artefactual. In this article, we argue that although many features of Venus can rule out the possibility that Earth life could live there, none rule out the possibility of all life based on what we know of the physical principle of life on Earth. Specifically, there is abundant energy, the energy requirements for retaining water and capturing hydrogen atoms to build biomass are not excessive, defenses against sulfuric acid are conceivable and have terrestrial precedent, and the speculative possibility that life uses concentrated sulfuric acid as a solvent instead of water remains. Metals are likely to be available in limited supply, and the radiation environment is benign. The clouds can support a biomass that could readily be detectable by future astrobiology-focused space missions from its impact on the atmosphere. Although we consider the prospects for finding life on Venus to be speculative, they are not absent. The scientific reward from finding life in such an un-Earthlike environment justifies considering how observations and missions should be designed to be capable of detecting life if it is there.

show abstract

Nitrogen Fixation, a Molybdenum-Requiring Process

Cited by 3 publications

References 27 publications

Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium–Legume Symbiosis

Coupling between Nitrogen Fixation and Tetrachlorobiphenyl Dechlorination in a Rhizobium–Legume Symbiosis

Draft Genome Sequence of Klebsiella sp. Strain C31 Isolated from a Malaysian Tropical Peat Swamp Forest

Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life

Contact Info

Product

Resources

About