Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, 361005, PR China.
Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, The Key Laboratory for Synthetic Biotechnology of Xiamen City, Xiamen University, Xiamen, 361005, PR China.
Environ Res. 2024 Jan 1;240(Pt 1):117595. doi: 10.1016/j.envres.2023.117595. Epub 2023 Nov 4.
Excessive nitrogen (N) discharged in water is a major cause of eutrophication and other severe environmental issues. Biological N removal via heterotrophic nitrification and aerobic denitrification (HN-AD) has drawn particular attention, owing to the merit of concurrent nitrification and denitrification inside one cell. However, the mechanisms underlying N transformation during HN-AD remain unclear. In the present study, the HN-AD strain Pseudomonas sp. Y15 (Y15) was isolated to explore the N distribution and flow, based on stoichiometry and energetics. The total N removal efficiency by Y15 increased linearly with C/N ratio (in the range of 5-15) to ∼96.8%. Of this, ∼32.2% and ∼64.6% were transformed into gas-N and biomass-N, respectively. A new intracellular N metabolic bypass (NO → NO) was found, to address the substantial gaseous N production during HN-AD. Concering energetics, the large portion of the biomass-N is ascribed to the synthesis of the amino acids that consume low energy. Finally, two novel stoichiometric equations for different N sources were proposed, to describe the overall HN-AD process. This study deepens the fundamental knowledge on HN-AD bacteria and enlightens their use in treating N-contaminated wastewater.
过量的氮（N）排入水中是富营养化和其他严重环境问题的主要原因。由于细胞内同时进行硝化和反硝化，异养硝化和好氧反硝化（HN-AD）去除生物氮引起了特别关注。然而，HN-AD 过程中 N 转化的机制仍不清楚。在本研究中，基于化学计量学和能量学，分离出一株具有 HN-AD 能力的假单胞菌（Pseudomonas sp. Y15，Y15），以探索 N 的分布和流动。Y15 对总氮的去除效率随 C/N 比（5-15）的增加呈线性增加，达到约 96.8%。其中，约 32.2%和约 64.6%分别转化为气体-N 和生物质-N。发现了一种新的细胞内 N 代谢旁路（NO→NO），以解决 HN-AD 过程中大量气态 N 的产生。关于能量学，大量的生物质-N 归因于合成消耗低能量的氨基酸。最后，提出了两个用于不同氮源的新的化学计量方程，以描述整个 HN-AD 过程。本研究深化了对 HN-AD 细菌的基础认识，并为其在处理含氮废水方面的应用提供了启示。
