PARTICIPATION OF INTERMEDIATES OF CATABOLISM OF GLUTAMINE IN PROCESSES OF MICROBIAL AMMONIAGENESIS IN THE RUMEN
М. S. Kalachnyuk1, D. О. Mel’nychuk1, L. G. Kalachnyuk1,
М. Мarounek2, O. G. Savka2, G.I. Kalachnyuk1
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1National Universityof Life and Environmental Sciences of Ukraine,
Heroiv Oborony str.,15; Kyiv, 03041, Ukraine
2Institute of Animal Physiology and Genetics, Academy of Science
of the Czech Republic, 142 20 Prague, Czech Republic
With classic and contemporary research methods, in experiments in vitro, conversion of glutamine was clarified by complex of microorganisms-symbionts of ruminal inoculates which were taken through the fistula resulting from calves with prevailing ruminal type of digestion. During the 96-hour incubation, at each selection of aliquot of the culture medium biochemical parameters of control and experimental samples were determined.
Intoexperimental media, it was added, besides 40 mM glutamine or glutamate, ionophore MonensinSodiumin the end-concentration 5 mg/L.
Particular attention is paid to the definition of concentration of hydrogen ions (рН), redox potential (Eh), NH3, protein, glutamine, total and individual volatile fatty acids (VFA) etc., and alsoactivity of the enzyme α-ketoglutarate dehydrogenase, glutamine synthetase, L-aspartate: 2-oxo-glutarate aminotransferase and L-alanine: 2-oxo-glutarate aminotransferase.
It has been shownthat cells of mixed population ofruminal microorganisms-symbionts metabolize glutamine through producing glutamate and pyro-glutamate (pyrrolidone carboxylic acid) to ammonia and low molecular carboxylic acids.
The process of glutamine transformation accompanied by specific changes in the physico-chemical properties of the culture medium and, above all, a significantly shift towards less negative values of Eh and pH increase, which is ambiguous effect on enzyme reactions involved in the metabolism of glutamic acid amide and its intermediates (it’s inhibited activity of α-ketoglutarate dehydrogenase and activated aminotransferases on rising content of intermediate and final products of degradation of glutamine).
Monensin has the ability to protect significantly glutamine and its intermediates such as glutamate and pyro-glutamate from rapid microbial degradation, as evidenced by a significant decrease in the levels of pH, ammonia, total VFA, acetate, butyrate, activity α-keto-glutarate dehydrogenase and glutamine synthetase by a parallel increase in levels of redox potential, activity of aminotransferases and protein fund.
Ionophore regulatory role in the process of assimilation of nitrogen in the rumen is most clearly reflected in its selective inhibition of growth and development of Gram-positive bacteria (the structure of cell walls and membranes which are different both in Gram-negative bacteria) and inhibition of enzyme reactions involved in the mechanisms of metabolism of glutamine, glutamate and pyro- glutamate, which apparently operate in a single cycle of intracellular and exocellular transformations of nitrogen-containing compounds.
Keywords:RUMINAL MICROORGANISMS-SYMBIONTS, CATABOLISM OF GLUTAMINE, GLUTAMATE, PYRO-GLUTAMATE, AMMONIAGENESIS, MICROBIAL ENZYMES, RUMINANT ANIMALS
