title: Dissimilatory reduction of nitrate and nitrite in the bovine rumen: nitrous oxide production and effect of acetylene.
abstract: 15N tracer methods and gas chromatography coupled to an electron capture detector were used to investigate dissimilatory reduction of nitrate and nitrite by the rumen microbiota of a fistulated cow. Ammonium was the only 15N-labeled end product of quantitative significance. Only traces of nitrous oxide were detected as a product of nitrate reduction; but in experiments with nitrite, up to 0.3% of the added nitrogen accumulated as nitrous oxide, but it was not further reduced. Furthermore, when 13NO3- was incubated with rumen microbiota virtually no [13N]N2 was produced. Acetylene partially inhibited the reduction of nitrite to ammonium as well as the formation of nitrous oxide. It is suggested that in the rumen ecosystem nitrous oxide is a byproduct of dissimilatory nitrite reduction to ammonium rather than a product of denitrification and that the latter process is absent from the rumen habitat.
mesh_terms: D000114:Acetylene / Q000494:pharmacology; D000818:Animals; D001419:Bacteria / Q000378:metabolism*; D002417:Cattle; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D009609:Nitrous Oxide / Q000378:metabolism*; D010084:Oxidation-Reduction; D000644:Quaternary Ammonium Compounds / Q000378:metabolism; D012417:Rumen / Q000382:microbiology*
chemical_list: D009566:Nitrates; D009573:Nitrites; D000644:Quaternary Ammonium Compounds; D009609:Nitrous Oxide; D000114:Acetylene