Inhibition of nitrogenase activity by ammonium chloride in Azotobacter vinelandii

Klugkist, J.; Haaker, H.

doi:10.1128/jb.157.1.148-151.1984

Cited by 60 publications

(16 citation statements)

References 21 publications

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“…3B) and ammonia (not shown), both of which inhibit nitrogenase synthesis (10). However, the rapidity of the nitrate inhibition suggests a very active assimilatory (or dissimilatory) nitrate reductase coupled with an ammonia "fswitch off' reaction (13,18,20,36). Similar observations were reported for salt marsh sediments with regard to the sensitivity of NA to nitrate and ammonium (9).…”

Section: Discussionsupporting

confidence: 69%

Nitrogen Fixation Dynamics of Two Diazotrophic Communities in Mono Lake, California

Oremland

1990

Appl Environ Microbiol

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Two types of diazotrophic microbial communities were found in the littoral zone of alkaline hypersaline Mono Lake, California. One consisted of anaerobic bacteria inhabiting the flocculent surface layers of sediments. Nitrogen fixation (acetylene reduction) by flocculent surface layers occurred under anaerobic conditions, was not stimulated by light or by additions of organic substrates, and was inhibited by 2, nitrate, and ammonia. The second community consisted of a ball-shaped association of a ifiamentous chlorophyte (Ctenocladus circinnatus) with diazotrophic, nonheterocystous cyanobacteria, as well as anaerobic bacteria (Ctenocladus balls). Nitrogen fixation by Ctenocladus balls was usually, but not always, stimulated by light. Rates of anaerobic dark fixation equaled those in the light under air. Fixation in the light was stimulated by 3-(3,4-dichlorophenyl)-1,1-dimethylurea and by propanil [N-(3,4-dichlorophenyl)propanamide]. 3-(3,4-Dichlorophenyl)-1,1-dimethyl urea-elicited nitrogenase activity was inhibited by ammonia (96%) and nitrate (65%). Fixation was greatest when Ctenocladus balls were incubated anaerobically in the light with sulfide. Dark anaerobic fixation was not stimulated by organic substrates in short-term (4-h) incubations, but was in long-term (67-h) ones. Areal estimates of benthic N2 fixation were measured seasonally, using chambers. Highest rates (-29.3 ,umol of C2H4 m2 h 1) occurred under normal diel regimens of light and dark. These estimates indicate that benthic N2 fixation has the potential to be a significant nitrogen source in Mono Lake.

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Section: Discussionsupporting

confidence: 69%

Nitrogen Fixation Dynamics of Two Diazotrophic Communities in Mono Lake, California

Oremland

1990

Appl Environ Microbiol

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“…For molecular mass markers see the preceding paper [6]. Nitrogenase activity of whole cells was measured at different oxygen input rates as described earlier [15]. The maximum activity is given in the text.…”

Section: Methodsmentioning

confidence: 99%

Studies on the mechanism of electron transport to nitrogenase in Azotobacter vinelandii

Klugkist¹,

Haaker²,

Veeger³

1986

European Journal of Biochemistry

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The involvement of the cytoplasmic membrane in electron transport to nitrogenase has been studied. Evidence shows that nitrogenase activity in Azotobacter vinelandii is coupled to the flux of electrons through the respiratory chain.To obtain information about proteins involved, the changes occurring in A. vinelandii cells transferred to nitrogen-free medium after growth on NH4CI (derepression of nitrogenase activity) were studied. Synthesis of the nitrogenase polypeptides was detectable 5 min after transfer to nitrogen-free medium. No nitrogenase activity could be detected until t = 20 min, whereupon a linear increase of nitrogenase activity with time was observed. Synthesis of nitrogenase was accompanied by synthesis of flavodoxin I1 and two membrane-bound polypeptides of M , 29000 and 30000. Analysis with respect to changes in membrane-bound NAD(P)H dehydrogenase activities revealed the induction of an NADPH dehydrogenase activity, which was not detectable in membranes isolated from cells grown in the presence of NH40Ac. This induced activity was associated with the appearance of a polypeptide of M , 29 000 in the NADPH dehydrogenase complex.The enzyme nitrogenase is capable of reducing atmospheric N2 to ammonia. For activity the enzyme needs an anaerobic environment, MgATP and a strong reductant. How this reductant is generated in the aerobic nitrogen-fixing bacterium Azotobacter vinelandii is not well understood. In 1971 Benemann et al.[l] proposed a linear electron transfer pathway from NADPH to nitrogenase, including both ferredoxin and flavodoxin. However the nitrogenase activity measured with endogenous proteins was less than 5% of the activity with dithionite as electron donor. Haaker et al. [2, 31 have critisized the proposed model as being too simplistic with respect to the redox potentials of the different components of the electron transfer chain. It has been shown by the same authors [4] that a high proton motive force across the cytoplasmic membrane is required for nitrogenase activity. The membrane potential was found to be an especially important factor [5]. Recently it has been shown that A . vinelandii is able to make at least three different flavodoxins [6]. Flavodoxin I1 is most likely to be the reductant for nitrogenase [6]. Whether ferredoxin is involved in electron transport to nitrogenase in vivo is uncertain [6, 71. An enzyme system capable of reducing flavodoxin I1 has still to be found. This paper describes the changes observed in A . vinelandii cells transferred to nitrogen-free medium after growth in the presence of NH4Cl. For Azotobacter species it is known that, when sufficient NH; is supplied to cells, synthesis of the nitrogenase proteins [S] and possibly also 13 other nij-specific polypeptides [9] is repressed. It has been investigated whether, during derepression, the (membrane) proteins necessary for electron transport to nitrogenase are synthesized simultaneously with the nitrogenase proteins. In addition, a comparison has been made between the membrane-bound NAD(P)H dehy...

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“…One of the main goals of this work was to explore the influence of bottom water hypoxia on N 2 fixation. However, since NH 4 + concentration may vary at the different sites we studied, and NH 4 + has been shown to inhibit N 2 fixation for some organisms (Daesch & Mortenson 1972, Drozd et al 1972, Klugkist & Haaker 1984 including the Geobacteraceae (Holmes et al 2004(Holmes et al , 2006 known to be active in Narragansett Bay sediments (Brown & Jenkins 2014), we considered its potential effects on NA. The average pore water concentrations of NH 4 + were measured at sampling sites in 2013 and in 2014 ( Fig.…”

Section: N Fixation Occurs In a Background Of High Nh 4 + Levelsmentioning

confidence: 99%

Diazotroph activity in surface Narragansett Bay sediments in summer is stimulated by hypoxia and organic matter delivery

Spinette¹,

Brown²,

Ehrlich³

et al. 2019

Mar. Ecol. Prog. Ser.

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Bacteria that carry out many processes of the nitrogen cycle inhabit estuarine sediments. Denitrification is known to be a dominant process causing estuarine sediments to behave as net nitrogen sinks. However, measurements of nitrogen fluxes in the sediments of Narragansett Bay, Rhode Island, USA, have at times revealed high rates of net nitrogen (N 2 ) fixation. Whereas changes in primary production, in magnitude and phenology, within Narragansett Bay have been identified as possible causes for these changes in nitrogen cycling within the benthos, a factor that has not been examined thus far is seasonal hypoxia. Since anaerobic diazotrophs figure so prominently within the sediments of Narragansett Bay, we hypothesized that dissolved oxygen concentrations in the bottom waters affect their activity. In order to explore this relationship, we measured the activity of diazotrophs in the surface sediments of 3 study areas during the summers of 2013 and 2014 using the acetylene reduction assay. We explored the effects of several water quality parameters on nitrogenase activity including, among others, dissolved oxygen and chlorophyll concentrations. Our measurements of nitrogenase activity were generally low, ranging between 2 and 5 nmol ethylene g −1 d −1 but spiked to 16 nmol ethylene g −1 d −1 at an area experiencing severe hypoxia in July 2013. Our data suggest that diazotrophy in estuarine sediments is enhanced when the benthos experiences very low dissolved oxygen in conjunction with recent influxes of autochthonous organic matter. Experiments with sediment core incubations conducted in the laboratory support our hypothesis that low dissolved oxygen and organic matter additions promote N 2 fixation.

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Inhibition of nitrogenase activity by ammonium chloride in Azotobacter vinelandii

Cited by 60 publications

References 21 publications

Nitrogen Fixation Dynamics of Two Diazotrophic Communities in Mono Lake, California

Nitrogen Fixation Dynamics of Two Diazotrophic Communities in Mono Lake, California

Studies on the mechanism of electron transport to nitrogenase in Azotobacter vinelandii

Diazotroph activity in surface Narragansett Bay sediments in summer is stimulated by hypoxia and organic matter delivery

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