Effect of NaCl on aerobic denitrification by strain Achromobacter sp. GAD-3
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This paper presents the effect of NaCl on aerobic denitrification by a novel aerobic denitrifier strain Achromobacter sp. GAD-3. Results indicated that the aerobic denitrification process was inhibited by NaCl concentrations ≥20 g L−1, leading to lower nitrate removal rates (1.67∼4.0 mg L−1 h−1), higher nitrite accumulation (50.2∼87.4 mg L−1), and increasing N2O emission ratios (13∼72 mg L−1/mg L−1). Poor performance of aerobic denitrification at high salinity was attributed to the suppression of active microbial biomass and electron donating capacity of strain GAD-3. Further studies on the corresponding inhibition of the denitrifying gene expression by higher salinities revealed the significant sensitivity order of nosZ (for N2O reductase) > cnorB (for NO reductase) ≈ nirS (for cytochrome cd(1) nitrite reductase) > napA (for periplasmic nitrate reductase), accompanied with a time-lapse expression between nosZ and cnorB based on reverse transcription and real-time quantitative polymerase chain reaction (RT-qPCR) analysis. The insights into the effect of NaCl on aerobic denitrification are of great significance to upgrade wastewater treatment plants (WWTPs) containing varying levels of salinity.
Key wordsNaCl Aerobic denitrification Achromobacter sp. ETSA Gene expression Sensitivity
Financial support was from the National Natural Science Foundation of China (Grant No. 51539001).
Compliance with ethical standards
This article does not contain any studies with human participants or animals performed by any of the authors.
Conflict of interest
The authors declare that they have no conflict of interest.
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