Nitrogen metabolism in Xanthobacter H4-14

Murrell, J. Colin; Lidstrom, Mary E.

doi:10.1007/bf00409848

Cited by 14 publications

(9 citation statements)

References 15 publications

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“…Genome sequencing of the strain of X. autotrophicus used here (SI Appendix, Table S3) indicates that the NH 3 generated from N 2 ase is incorporated into biomass via a two-step process mediated by glutamine synthetase (GS) and glutamate synthase (GOGAT) (Fig. 4A), as is consistent with previous biochemical assays (41). If the functionality of this NH 3 assimilation pathway is disrupted, direct production of extracellular NH 3 should occur.…”

Section: Resultssupporting

confidence: 78%

Ambient nitrogen reduction cycle using a hybrid inorganic–biological system

Liu

Sakimoto

Colón

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

191

220

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We demonstrate the synthesis of NH 3 from N 2 and H 2 O at ambient conditions in a single reactor by coupling hydrogen generation from catalytic water splitting to a H 2 -oxidizing bacterium Xanthobacter autotrophicus, which performs N 2 and CO 2 reduction to solid biomass. Living cells of X. autotrophicus may be directly applied as a biofertilizer to improve growth of radishes, a model crop plant, by up to ∼1,440% in terms of storage root mass. The NH 3 generated from nitrogenase (N 2 ase) in X. autotrophicus can be diverted from biomass formation to an extracellular ammonia production with the addition of a glutamate synthetase inhibitor. The N 2 reduction reaction proceeds at a low driving force with a turnover number of 9 × 10 9 cell -1 and turnover frequency of 1.9 × 10 4 s -1 ·cell -1 without the use of sacrificial chemical reagents or carbon feedstocks other than CO 2 . This approach can be powered by renewable electricity, enabling the sustainable and selective production of ammonia and biofertilizers in a distributed manner.nitrogen fixation | Xanthobacter | ammonia synthesis | fertilizer | solar

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Section: Resultssupporting

confidence: 78%

Ambient nitrogen reduction cycle using a hybrid inorganic–biological system

Liu

Sakimoto

Colón

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

191

220

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“…In agreement with other reports (7,23,25), we could obtain steady states when nitrogen fixation was comparatively low and 02 concentrations were accordingly high.…”

Section: Discussionsupporting

confidence: 93%

“…Aerobic bacteria fixing nitrogen under microaerobic conditions can differ in their tolerance to oxygen (11,17,23,25). Since roots of Kallar grass contain aerenchymatic tissue (B. Reinhold, M.S.…”

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confidence: 99%

Root-Zone-Specific Oxygen Tolerance of Azospirillum spp. and Diazotrophic Rods Closely Associated with Kallar Grass

Hurek

Reinhold

Fendrik

et al. 1987

Appl Environ Microbiol

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The effect of oxygen on N2-dependent growth of two Azospirillum strains and two diazotrophic rods closely associated with roots of Kallar grass (Leptochloa fusca) was studied. To enable precise comparison, bacteria were grown in dissolved-oxygen-controlled batch and continuous cultures. Steady states were obtained from about 1 to 30 ,IM 02, some of them being carbon limited. All strains needed a minimum amount of oxygen for N2-dependent growth. Nitrogen contents between 10 and 13% of cell dry weight were observed. The response of steady-state cultures to increasing 02 concentrations suggested that carbon limitation shifted to internal nitrogen limitation when N2 fixation became so low that the bacteria could no longer meet their requirements for fixed nitrogen. For Azospirillum lipoferum Rp5, increase of the dilution rate resulted in decreased N2 fixation in steady-state cultures with internal nitrogen limitation. Oxygen tolerance was found to be strain specific in A. lipoferum with strain SpS9b as a reference organism. Oxygen tolerance of strains from Kallar grass was found to be root zone specific. A. halopraeferens Au 4 and A. lipoferum Rp5, predominating on the rhizoplane of Kallar grass, and strains H6a2 and BH72, predominating in the endorhizosphere, differed in their oxygen tolerance profiles. Strains H6a2 and BH72 still grew and fixed nitrogen in steady-state cultures at 02 concentrations exceeding those which absolutely inhibited nitrogen fixation of both Azospirillum strains. It is proposed that root-zone-specific oxygen tolerance reflects an adaptation of the isolates to the microenvironments provided by the host plant.

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“…Phylogenetically diverse, ubiquitous and often metabolically versatile, methylotrophs play major roles in C1-cycling in marine habitats (Anthony, 1982;Strand and Lidstrom, 1984;Neufeld et al, 2007a;Giovannoni et al, 2008;Chen, 2012). A wide range of non-methylotrophic organisms, some of which can be found in marine environments, can also degrade methylamine to CO 2 and ammonium, the latter being used as a nitrogen source by these and other microorganisms (Budd and Spencer, 1968;Bicknell and Owens, 1980;Anthony, 1982;Murrell and Lidstrom, 1983;Chen et al, 2010a;Wischer et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Methylamine as a nitrogen source for microorganisms from a coastal marine environment

Taubert

Grob

Howat

et al. 2017

Environmental Microbiology

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Nitrogen is a key limiting resource for biomass production in the marine environment. Methylated amines, released from the degradation of osmolytes, could provide a nitrogen source for marine microbes. Thus far, studies in aquatic habitats on the utilization of methylamine, the simplest methylated amine, have mainly focussed on the fate of the carbon from this compound. Various groups of methylotrophs, microorganisms that can grow on one-carbon compounds, use methylamine as a carbon source. Non-methylotrophic microorganisms may also utilize methylamine as a nitrogen source, but little is known about their diversity, especially in the marine environment. In this proof-of-concept study, stable isotope probing (SIP) was used to identify microorganisms from a coastal environment that assimilate nitrogen from methylamine. SIP experiments using N methylamine combined with metagenomics and metaproteomics facilitated identification of active methylamine-utilizing Alpha- and Gammaproteobacteria. The draft genomes of two methylamine utilizers were obtained and their metabolism with respect to methylamine was examined. Both bacteria identified in these SIP experiments used the γ-glutamyl-methylamide pathway, found in both methylotrophs and non-methylotrophs, to metabolize methylamine. The utilization of N methylamine also led to the release of N ammonium that was used as nitrogen source by other microorganisms not directly using methylamine.

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Nitrogen metabolism in Xanthobacter H4-14

Cited by 14 publications

References 15 publications

Ambient nitrogen reduction cycle using a hybrid inorganic–biological system

Ambient nitrogen reduction cycle using a hybrid inorganic–biological system

Root-Zone-Specific Oxygen Tolerance of Azospirillum spp. and Diazotrophic Rods Closely Associated with Kallar Grass

Methylamine as a nitrogen source for microorganisms from a coastal marine environment

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