School of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China.
School of Life and Environmental Sciences, Hangzhou Normal University, Hangzhou 311121, China; School of Engineering, Hangzhou Normal University, Hangzhou 310018, China.
Water Res. 2022 Sep 1;223:119033. doi: 10.1016/j.watres.2022.119033. Epub 2022 Aug 28.
External stimulus such as light irradiation is able to deteriorate intracellular redox homeostasis and induce photooxidative damage to non-photogenic bacteria. Exploiting effective strategies to help bacteria resisting infaust stress is meaningful for achieving a stable operation of biological treatment system. In this work, selenium-doped carbon quantum dots (Se-CQDs) were blended into anaerobic ammonia oxidation (anammox) bacteria and an inorganic nanoparticle-microbe hybrid was successfully fabricated to evaluate its nitrogen removal performance under solar-simulated irradiation. It was found that the specific anammox activity decreased by 29.7 ± 5.2% and reactive oxygen species (ROS) content increased by 134.8 ± 4.1% under 50,000 lux light. Sludge activity could be completely recovered under the optimum dosage of 0.42 mL·(g volatile suspended solid) Se-CQDs. Hydroxyl radical (·OH) and superoxide anion radical (·O) were identified as the leading ROS inducing lipid peroxidation and antioxidase function detriment. Also, the structure of ladderane lipids located on anammoxosome was destroyed by ROS and functional genes abundances declined accordingly. Although cell surface coated Se-CQDs could absorb ultraviolet light and partially mitigated the photoinhibition, the direct scavenging of ROS by intracellular Se-CQDs primarily contributed to the cellular redox homeostasis, antioxidase activity recovery and sludge activity improvement. The findings of this work provide in-depth understanding the metabolic response mechanism of anammox consortia to light irradiation and might be valuable for a more stable and sustainable nitrogen removal technology, i.e., algal-bacterial symbiotic system, development.
外部刺激，如光照，能够破坏细胞内的氧化还原稳态，并诱导非光生细菌发生光氧化损伤。利用有效的策略帮助细菌抵抗恶劣的应激是实现生物处理系统稳定运行的有意义的方法。在这项工作中，硒掺杂碳量子点（Se-CQDs）被混入厌氧氨氧化（anammox）细菌中，并成功制备了无机纳米颗粒-微生物杂化体，以评估其在模拟太阳光照射下的脱氮性能。结果发现，在 50000lux 光下，特定的 anammox 活性下降了 29.7±5.2%，活性氧（ROS）含量增加了 134.8±4.1%。在 0.42mL·(g 挥发性悬浮固体) Se-CQDs 的最佳剂量下，污泥活性可以完全恢复。羟基自由基（·OH）和超氧阴离子自由基（·O）被鉴定为主要的 ROS，导致脂质过氧化和抗氧化酶功能受损。此外，位于厌氧氨氧化体上的 ladderane 脂质的结构被 ROS 破坏，相应的功能基因丰度下降。尽管细胞表面涂覆的 Se-CQDs 可以吸收紫外线，并部分缓解光抑制，但细胞内 Se-CQDs 对 ROS 的直接清除主要有助于细胞氧化还原稳态、抗氧化酶活性的恢复和污泥活性的提高。这项工作的结果深入了解了 anammox 菌群对光照的代谢响应机制，对于更稳定和可持续的脱氮技术（即藻类-细菌共生系统）的发展可能具有重要意义。
