Clues to the mechanism of biological nitrogen fixation have been sought through experiments aimed at defining the substances specifically required by organisms to effect the process. The nitrogen-fixing sequence in bacteria is known to proceed through ammonia (Zelitch et al., 1951; Newton et al., 1953; Wilson and Burris, 1953; Virtanen, 1953). Thus, the effect of adding ammonium salts to a fixi...

Cheviot wethers were defaunated by using dioctyl sodium sulfosuccinate and were constantly infused with urea to provide 2.87% of the daily N intake. Defaunation resulted in higher rumen dry matter and lower rumen pH. The molar per cent propionate was higher in defaunated sheep, whereas the molar per cent butyrate and acetate was lower. Apparent nitrogen digestibility, nitrogen utilization, and ...

Addition of ammonium salts to E. coli cells grown on a medium with glutamate as the sole nitrogen source is followed by rapid inactivation of glutamine synthetase (GS) I1 The active form of the enzyme (GSa) and the inactive form (GSb) have been isolated.2 Both forms behave similarly in the analytical ultracentrifuge, electrophoresis, and ion exchange chromatography. 2 In a cell-free system GSa ...

Studies in which (15)N-labeled precursors of urinary ammonia were infused into the artery of an intact functioning kidney of an acidotic dog have led to the following conclusions: Preformed ammonia and ammonia derived from the amide nitrogen of plasma glutamine are added directly to urine without significant incorporation into amino acid intermediates of renal tissue. Thus, reductive amination ...

A method has been developed to prepare fresh forages for in sacco and in vitro incubation by freezing and mincing to achieve a particle size distribution of dry matter (DM) similar to in vivo conditions. The method is described and data presented to indicate losses of nitrogen (N) during in sacco digestion and net yield of ammonia from proteolysis in vitro for 22 fresh and conserved forages. Gr...

Accumulation of ammonia, measured as total ammonia nitrogen (TAN), a product of protein decomposition in slaughterhouse wastes, inhibits the anaerobic digestion process, reducing digester productivity and leading to failure. Struvite precipitation (SP) is an effective means to remove TAN and enhance the buffering of substrates. Different Mg and P sources were evaluated as reactants in SP in aci...

OBJECTIVE The objective of this study was to evaluate the intake and nutrient digestibility, nitrogen balance and ruminal ammonia nitrogen in lambs of diets containing different levels of residual frying oil. METHODS Levels of 0, 20, 40, 60, and 80 g/kg dry matter (DM) base of residual frying oil in the diets of lambs were evaluated. Five castrated lambs with initial body weights of 36.8±3.3 ...

The pentahaem enzyme cytochrome c nitrite reductase catalyses the reduction of nitrite to ammonia, a key reaction in the biological nitrogen cycle. The enzyme can also transform nitrogen monoxide and hydroxylamine, two potential bound reaction intermediates, into ammonia. Structural and mechanistic aspects of the multihaem enzyme are discussed in comparison with hydroxylamine oxidoreductase, a ...

Pathways of ammonia assimilation into glutamic acid were investigated in ammonia-grown and N2-fixing Clostridium kluyverii and Clostridium butyricum by measuring the specific activities of glutamate dehydrogenase, glutamine synthetase, and glutamate synthase. C. kluyverii had NADPH-glutamate dehydrogenase with a Km of 12.0 mM for NH4+. The glutamate dehydrogenase pathway played an important rol...

The utilization of nitrate and ammonia as nitrogen sources had different effects on the metabolism of glycolate in Cholorella sorokiniana. During photolithotrophic growth with nitrate as nitrogen source, glycolate was metabolized via the glycine-serine pathway. Ammonia, produced as a result of glycolate metabolism, was reassimilated by glutamine synthetase. Two isoforms of this enzyme were pres...