Carbon Metabolism in Legume Nodules

Streeter, John G.; Salminen, Seppo O.

doi:10.1007/978-94-009-5175-4_39

Cited by 21 publications

(13 citation statements)

References 29 publications

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“…The most recent evidence from studies of mutants of various species of Rhizobium (Arwas et al, 1985;Finan et al, 1983;Ronson et al, 1981 ;Streeter & Salminen, 1985) supports results of other studies (e.g. Peterson & LaRue, 1981 ;Saroso et al, 1984;Tuzimura & Meguro, 1960), which conclude that the tricarboxylic acid cycle acids succinate and malate are the principal energy sources for the symbiotic N2 fixing bacteroids in the root nodules of legumes.…”

Section: Introductionsupporting

confidence: 56%

Glutamate as a Carbon Source for N2-Fixing Bacteroids Prepared from Soybean Root Nodules

Bergersen¹,

Turner²

1988

Microbiology

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The possibility that glutamate might serve as a source of reducing power, supporting fixation of N2 to NH3 by bacteroids in soybean root nodules, was investigated. Suspensions of bacteroids were retained within a reaction chamber supplied with a flow of solution containing dissolved air, buffer, oxyleghaemoglobin and either disodium glutamate (1 or 10mM) or no added substrate (2 or 20 mM-NaC1). The solution passing out of the chamber was analysed for dissolved NH3 and proportional oxygenation of leghaemoglobin was determined spectrophotometrically. Rates of production of NH3 and of consumption of O2 and the concentrations of free, dissolved O2 prevailing during steady states were calculated. At 1 mM, glutamate stimulated O2 demand of the bacteroids and enhanced NH, production. However, increased production of NH3 was shown to arise entirely from deamination of [lSN]glutamate and not from N2 fixation. At 10 mM-glutamate, the proportion of NH3 arising from [I SN]glutamate increased with increased steady state concentrations of free, dissolved O2 in the chamber, but there was also significant and efficient stimulation of N2 fixation when the concentration of free, dissolved O2 was between 10 and 70nM. The kinetics of O2 consumption by bacteroids using endogenous substrates or 10 mmglutamate were similar.

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Section: Introductionsupporting

confidence: 56%

Glutamate as a Carbon Source for N2-Fixing Bacteroids Prepared from Soybean Root Nodules

Bergersen¹,

Turner²

1988

Microbiology

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“…Most of the available evidence supports the idea that the tricarboxylic acid cycle acids succinate and malate are the compounds supplied to N2-fixing bacteroids in legume nodules (23). Much of the recent support for this proposition comes from studies showing that bacterial mutants lacking the ability to absorb dicarboxylic acids form nodules that are incapable of N2 fixation (2,7,18).…”

mentioning

confidence: 97%

Involvement of glutamate in the respiratory metabolism of Bradyrhizobium japonicum bacteroids

Salminen¹,

Streeter²

1987

J Bacteriol

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pestle, with 0.15 M sodium phosphate buffer, pH 7.5, added in 2-ml portions to a final volume of 2 ml of buffer per g of nodules. The homogenate was filtered through two Miracloth disks in a 50-ml syringe into a 30-ml centrifuge tube. The tube was capped tightly and centrifuged at 6,000 x g for 10 min. The tube was opened in the glove box, the supernatant was discarded, and the pellet was washed twice by pipetting 1 ml of the buffer over it. The pellet was resuspended, and the mixture was again filtered through Miracloth disks to remove any unsuspended bacteroids and adjusted to a final concentration of 2 ml of buffer per g of nodules. This (16), and 0.3 ml of 0.15 M sodium phosphate buffer, pH 7.5. The tubes were flushed with N2 and sealed with a serum stopper with an attached cup containing a filter paper wick impregnated with 70 p.l of 10% KOH. A sample (1.4 ml) was removed from the gas phase and replaced with 1.4 ml of , giving a final concentration of 2% 02 in the gas phase. Buffered substrate (0.5 ml; 1 ,umol at 1 ,uCi/,umol) was then injected into the reaction mixture, and the tubes were shaken in a rotary shaker at 250 rpm. Incubation was terminated by placing the tubes in an ice bath. The stoppers were quickly removed, and the tubes were centrifuged at 25,000 x g for 10 min. The supernatant was discarded, and the pellet was washed twice by pipetting 1 ml of the cold buffer over it and discarding the washes. The

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“…(1) Changes in levels and activities of enzymes of carbon metabolism to provide flexibility in the electron pressure for differential flux through the various limbs of the respiratory chain, e.g., (a) sugar catabolism [41][42][43], (b) tricarboxylic acid cycle components [44][45][46], and (c) polyhydroxybutyrate metabolism [41,47].…”

Section: 2 Gradients and Other Means Of Keeping 0 2 From Nitrogenasementioning

confidence: 99%

How is nitrogenase regulated by oxygen?

Hill

1988

FEMS Microbiology Letters

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Carbon Metabolism in Legume Nodules

Cited by 21 publications

References 29 publications

Glutamate as a Carbon Source for N2-Fixing Bacteroids Prepared from Soybean Root Nodules

Glutamate as a Carbon Source for N2-Fixing Bacteroids Prepared from Soybean Root Nodules

Involvement of glutamate in the respiratory metabolism of Bradyrhizobium japonicum bacteroids

How is nitrogenase regulated by oxygen?

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