National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
National Engineering Research Center of Industrial Wastewater Detoxication and Resource Recovery, School of Resources and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
Water Res. 2024 Oct 1;263:122144. doi: 10.1016/j.watres.2024.122144. Epub 2024 Jul 25.
High Pressure Hydrogenotrophic Denitrification (HPHD) provided a promising alternative for efficient and clean nitrate removal. In particular, the denitrification rates at low temperature could be compensated by elevated H partial pressure. However, nitrite reduction was strongly inhibited while nitrate reduction was barely affected at low temperature. In this study, the nitrate reduction gradually recovered under long-term low temperature stress, while nitrite accumulation increased from 0.1 to 41.0 mg N/L. The activities of the electron transport system (ETS), nitrate reductase (NAR), and nitrite reductase (NIR) decreased by 45.8 %, 27.3 %, and 39.3 %, respectively, as the temperature dropped from 30 °C to 15 °C. Real time quantitative PCR analysis revealed that the denitrifying gene expression rather than gene abundance regulated nitrogen biotransformation. The substantial nitrite accumulation was attributed to the significant up-regulation by 54.7 % of narG gene expression and down-regulation by 73.7 % of nirS gene expression in hydrogenotrophic denitrifiers. In addition, the nirS-gene-bearing denitrifiers were more sensitive to low temperature compared to those bearing nirK gene. The dominant populations shifted from the genera Paracoccus to Hydrogenophaga under long-term low temperature stress. Overall, this study revealed the microbial mechanism of high nitrite accumulation in hydrogenotrophic denitrification at low temperature.
高压氢气自养反硝化（HPHD）为高效、清洁的硝酸盐去除提供了一种很有前途的替代方法。特别是在低温条件下，通过提高 H 分压可以补偿反硝化速率。然而，在低温条件下，亚硝酸盐还原受到强烈抑制，而硝酸盐还原几乎不受影响。在这项研究中，硝酸盐还原在长期的低温胁迫下逐渐恢复，而亚硝酸盐积累从 0.1 增加到 41.0mg N/L。随着温度从 30°C 降至 15°C，电子传递系统（ETS）、硝酸盐还原酶（NAR）和亚硝酸盐还原酶（NIR）的活性分别下降了 45.8%、27.3%和 39.3%。实时定量 PCR 分析表明，反硝化基因表达而不是基因丰度调节氮的生物转化。大量的亚硝酸盐积累归因于氢自养反硝化菌中 narG 基因表达显著上调 54.7%，nirS 基因表达显著下调 73.7%。此外，与携带 nirK 基因的反硝化菌相比，携带 nirS 基因的反硝化菌对低温更为敏感。在长期的低温胁迫下，优势种群从 Paracoccus 属转向 Hydrogenophaga 属。总的来说，本研究揭示了低温氢气自养反硝化过程中高亚硝酸盐积累的微生物机制。
