In:
Applied and Environmental Microbiology, American Society for Microbiology, Vol. 76, No. 19 ( 2010-10), p. 6387-6396
Abstract:
Denitrification in soil is a major source of atmospheric N 2 O. Soil pH appears to exert a strong control on the N 2 O/N 2 product ratio (high ratios at low pH), but the reasons for this are not well understood. To explore the possible mechanisms involved, we conducted an in-depth investigation of the regulation of denitrification in the model organism Paracoccus denitrificans during transition to anoxia both at pH 7 and when challenged with pHs ranging from 6 to 7.5. The kinetics of gas transformations (O 2 , NO, N 2 O, and N 2 ) were monitored using a robotic incubation system. Combined with quantification of gene transcription, this yields high-resolution data for direct response patterns to single factors. P. denitrificans demonstrated robustly balanced transitions from O 2 to nitric oxide-based respiration, with NO concentrations in the low nanomolar range and marginal N 2 O production at an optimal pH of 7. Transcription of nosZ (encoding N 2 O reductase) preceded that of nirS and norB (encoding nitrite and NO reductase, respectively) by 5 to 7 h, which was confirmed by observed reduction of externally supplied N 2 O. Reduction of N 2 O was severely inhibited by suboptimal pH. The relative transcription rates of nosZ versus nirS and norB were unaffected by pH, and low pH had a moderate effect on the N 2 O reductase activity in cells with a denitrification proteome assembled at pH 7. We thus concluded that the inhibition occurred during protein synthesis/assembly rather than transcription. The study shed new light on the regulation of the environmentally essential N 2 O reductase and the important role of pH in N 2 O emission.
Type of Medium:
Online Resource
ISSN:
0099-2240
,
1098-5336
DOI:
10.1128/AEM.00608-10
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2010
detail.hit.zdb_id:
223011-2
detail.hit.zdb_id:
1478346-0
SSG:
12
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