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Effects of Oxygen on Denitrification Inhibition, Repression, and Derepression in Soil Columns
Author(s) -
McKenney D.J.,
Drury C.F.,
Wang S.W.
Publication year - 2001
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2001.651126x
Subject(s) - derepression , denitrifying bacteria , denitrification , anaerobic exercise , anoxic waters , chemistry , oxygen , aerobic denitrification , psychological repression , zoology , environmental chemistry , nitrogen , biochemistry , biology , gene expression , organic chemistry , gene , physiology
Although it is known that O 2 inhibits and represses denitrification, few studies have examined the effect of O 2 on NO production. Our objectives were to measure O 2 inhibition, repression, and derepression of NO and N 2 O production by denitrifying microorganisms in soil columns continuously purged by N 2 or various constant (0.074–15%) O 2 –N 2 mixtures. Net rates of NO and N 2 O production were measured under successive anaerobic, partially aerobic, and anaerobic conditions. Oxygen inhibition was rapid and reversible. Within 5 min after exposure to >5% O 2 , NO production was reduced to ≈50 to 58% and N 2 O rates to ≈29 to 32% of their maximum anaerobic rates. Maintaining O 2 at ≥5% in soil without added C or at >10% O 2 in C‐amended soil decreased (repressed) NO production rates by a factor of ≈1.5 to 1.8 d −1 Rates of N 2 O repression remained constant at ≈0.07 d −1 for all C and O 2 treatments. Restoration of anoxic conditions following the aerobic phase reversed inhibition; within 5 min, NO production rates by the nonrepressed denitrifiers increased to 55 to 101% of their respective anaerobic rates and N 2 O production rates increased to 26 to 62%. The rates of NO and N 2 O production then increased more slowly (derepression) during this anaerobic period. This research supports previous observations for O 2 effects on N 2 O production and apparently is the first systematic study of O 2 inhibition, repression, and derepression of NO production.