/sup 15/N kinetic analysis of N/sub 2/O production by Nitrosomonas europaea: an examination of nitrifier denitrification

Journal Article · Wed May 01 00:00:00 EDT 1985 · Appl. Environ. Microbiol.; (United States)

OSTI ID:6385162

Poth, M; Focht, D D

A series of /sup 15/N isotope tracer experiments showed that Nitrosomonas europaea produces nitrous oxide only under oxygen-limiting conditions and that the labeled N from nitrite, but not nitrate, is incorporated into nitrous oxide, indicating the presence of the denitrifying enzyme nitrite reductase. A kinetic analysis of the m/z 44, 45, and 46 nitrous oxide produced by washed cell suspensions of N. europaea when incubated with 4 mM ammonium (99% /sup 14/N) and 0.4 mM nitrite (99% /sup 15/N) was performed. No labeled nitirte was reduced to ammonium. All labeled material added was accounted for as either nitrite or nitrous oxide. The hypothesis that nitrous oxide is produced directly from nitrification was rejected since (i) it does not allow for the large amounts of double-labeled (m/z 46) nitrous oxide observed; (ii) the observed patterns of m/z 44, 45, 46 nitrous oxide were completely consistent with a kinetic analysis based on denitrification as the sole mechanism of nitrous oxide production but not with a kinetic analysis based on both mechanisms; (iii) the asymptotic ratio of m/z 45 to m/z 46 nitrous oxide was consistent with denitrification kinetics but inconsistent with nitrification kinetics, which predicted no limit to m/z 45 production. It is concluded that N. europaea is a denitrifier which, under conditions of oxygen stress, uses nitrite as a terminal electron acceptor and produces nitrous oxide.

• Research Organization: Univ. of California, Riverside
• OSTI ID: 6385162
• Journal Information: Appl. Environ. Microbiol.; (United States), Vol. 49:5
• Country of Publication: United States
• Language: English

Related Subjects

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
59 BASIC BIOLOGICAL SCIENCES
AMMONIUM COMPOUNDS
METABOLISM
NITROUS OXIDE
BIOSYNTHESIS
BACTERIA
DOUBLE LABELLING
NITRIFICATION
NITRITES
NITROGEN 14
NITROGEN 15
NITROGEN CYCLE
OXIDOREDUCTASES
TRACER TECHNIQUES
CHALCOGENIDES
CHEMICAL REACTIONS
ENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
LABELLING
LIGHT NUCLEI
MICROORGANISMS
NITROGEN COMPOUNDS
NITROGEN ISOTOPES
NITROGEN OXIDES
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
OXIDES
OXYGEN COMPOUNDS
STABLE ISOTOPES
SYNTHESIS
560302* - Chemicals Metabolism & Toxicology- Microorganisms- (-1987)
550501 - Metabolism- Tracer Techniques