Achieving Stable Partial Denitrification by Selective Inhibition of Nitrite Reductase with the Biosafe Aprotic
Zhi-Bin Wang1,2, Jinpeng Zhang1,3, Qinshu Miao1
1School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, China.
Environmental Science & Technology
|November 19, 2024
Summary
Dimethyl sulfoxide (DMSO) enables stable partial denitrification by selectively inhibiting nitrite reductase (NIR). This strategy ensures a consistent nitrite supply for anammox bacteria, crucial for wastewater treatment applications.
Area of Science:
- Environmental Microbiology
- Biochemical Engineering
Background:
- Partial denitrification (PD) is a promising method for supplying nitrite to anammox bacteria.
- Achieving stable nitrite accumulation in PD is challenging due to higher nitrate reductase activity than nitrite reductase (NIR).
Purpose of the Study:
- To develop an efficient and stable PD process using dimethyl sulfoxide (DMSO).
- To elucidate the mechanism by which DMSO selectively inhibits NIR activity.
Main Methods:
- Investigated the effect of DMSO on PD process stability and nitrite accumulation.
- Analyzed DMSO's impact on nitrite reductase (NIR) and nitrate reductase (NAR) gene expression and enzyme activity.
- Determined the binding affinity and mechanism of DMSO inhibition on NIR.
Main Results:
- DMSO addition effectively inhibited NIR gene expression and enzyme activity, enabling stable PD.
- 1% DMSO significantly inhibited NIR, while 3.5% DMSO almost completely suppressed its activity.
- DMSO exhibited higher affinity for NIR (-3.1 kcal/mol) than NAR (-2.4 kcal/mol), binding to the same catalytic site as nitrite.
- DMSO showed minimal inhibition on NAR activity.
Conclusions:
- DMSO is a safe and effective additive for achieving stable partial denitrification.
- Selective inhibition of NIR by DMSO provides a novel strategy for optimizing nitrite supply in biological wastewater treatment.
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