School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China.
School of Civil and Environmental Engineering, Harbin Institute of Technology Shenzhen, Shenzhen 518055, China; Shenzhen Key Laboratory of Water Resource Utilization and Environmental Pollution Control, Shenzhen 518055, China; State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
Bioresour Technol. 2023 Sep;384:129269. doi: 10.1016/j.biortech.2023.129269. Epub 2023 Jun 7.
This study investigated the response of nitrite accumulation to elevated COD/NO-N ratio (C/N) during partial denitrification (PD). Results indicated nitrite was gradually accumulated and remained stable (C/N = 1.5 ∼ 3.0), while that rapidly declined after reaching the peak (C/N = 4.0 ∼ 5.0). The polysaccharide (PS) and protein (PN) content of tightly-bound extracellular polymeric substances (TB-EPS) reached the maximum at C/N of 2.5 ∼ 3.0, which might be stimulated by high level of nitrite. Illumina MiSeq sequencing showed Thauera and OLB8 were dominated denitrifying genera at C/N of 1.5 ∼ 3.0, while Thauera was further enriched with fading OLB8 at C/N of 4.0 ∼ 5.0. Meanwhile, the highly-enriched Thauera might enhance the activity of nitrite reductase (nirK) promoting further nitrite reduction. Redundancy analysis (RDA) showed positive correlations between nitrite production and PN content of TB-EPS, denitrifying bacteria (Thauera and OLB8) and nitrate reductases (narG/H/I) in low C/N. Finally, their synergistic effects for driving nitrite accumulation were comprehensively elucidated.
本研究考察了部分反硝化（PD）过程中硝态氮积累对 COD/硝态氮比（C/N）升高的响应。结果表明，在 C/N 为 1.53.0 时，亚硝酸盐逐渐积累并保持稳定，而在 C/N 为 4.05.0 时迅速下降。紧密结合的胞外聚合物（TB-EPS）中的多糖（PS）和蛋白质（PN）含量在 C/N 为 2.53.0 时达到最大值，这可能是由于亚硝酸盐水平较高而受到刺激。Illumina MiSeq 测序表明，在 C/N 为 1.53.0 时，Thauera 和 OLB8 是主要的反硝化属，而在 C/N 为 4.0~5.0 时，Thauera 进一步富集，而 OLB8 逐渐消失。同时，高度富集的 Thauera 可能会增强亚硝酸盐还原酶（nirK）的活性，从而促进进一步的亚硝酸盐还原。冗余分析（RDA）表明，在低 C/N 条件下，亚硝酸盐的产生与 TB-EPS 的 PN 含量、反硝化菌（Thauera 和 OLB8）和硝酸盐还原酶（narG/H/I）之间呈正相关。最后，综合阐明了它们协同作用对亚硝酸盐积累的驱动作用。
