外源C12-HSL信号分子协同反硝化菌FX-4对活性污泥系统脱氮效果的影响

为探究外源信号分子的群体感应效应对反硝化菌FX-4及活性污泥系统脱氮的影响，将外源AHLs (酰基高丝氨酸内酯类) 的C6-HSL和C12-HSL信号分子投加至反硝化复筛培养基中，探究AHLs对反硝化菌FX-4去除NO₃⁻-N的影响。结果发现，外源投加C6-HSL和C12-HSL均可有效地提高反硝化菌FX-4的NO₃⁻-N去除性能，增加反硝化菌FX-4的生物量，且C12-HSL协同反硝化菌FX-4的NO₃⁻-N去除效果最佳；不同浓度的C12-HSL对反硝化菌FX-4的NO₃⁻-N去除效果均有提升，且50 nmol∙L⁻¹的C12-HSL可较大提升菌株FX-4的NO₃⁻-N去除效果。将浓度为0、5 nmol∙L⁻¹、50 nmol∙L⁻¹、200 nmol∙L⁻¹、500 nmol∙L⁻¹和1 000 nmol∙L⁻¹的C12-HSL和反硝化菌FX-4同时投加至SBR活性污泥系统中，考察两者协同下系统脱氮性能、信号分子浓度和微生物群落结构的变化。结果表明，两者协同作用可对NO₃⁻-N去除性能产生明显影响，投加信号分子的实验组R₁~R₆相对于空白对照组R₀的NO₃⁻-N积累量减少20~50 mg∙L⁻¹，且C12-HSL投加量为100 nmol∙L⁻¹的反应器R₃的NO₃⁻-N消耗量最多，NO₃⁻-N出水质量浓度较R₀降低约45 mg∙L⁻¹；此外C12-HSL信号分子对TN去除产生正影响显著，且C12-HSL投加量为100 nmol∙L⁻¹的反应器能更有效地提升活性污泥系统TN去除效能。信号分子浓度变化检测结果显示，外源投加C12-HSL可以刺激系统其他AHLs分泌，特别是促进系统C4-HSL的分泌。微生物群落结构分析结果显示，外源投加反硝化菌FX-4和信号分子C12-HSL可显著影响活性污泥中微生物群落组成，加快活性污泥中微生物种群演替，使Thauera、Brevundimonas等脱氮相关菌属占比升高。以上结果可为信号分子作为应急手段强化活性污泥系统生物脱氮性能提供参考。

Effect of exogenous C12-HSL signal molecule in coordination with denitrifying bacteria FX-4 on nitrogen removal in activated sludge system

In order to explore the influence of quorum sensing effect of exogenous signal molecules on denitrifying bacteria FX-4 and denitrification of activated sludge system, C6-HSL and C12-HSL signal molecules of exogenous AHLs (acyl homoserine lactones) were added into denitrifying resieve medium to explore the effect of AHLs on denitrifying bacteria FX-4's removal of NO3−-N. The experimental results showed that both C6-HSL and C12-HSL could effectively improve the NO3−-N removal performance of denitrifying bacterium FX-4 and increase the biomass of denitrifying bacterium FX-4, and C12-HSL synergic denitrifying bacterium FX-4 had the best NO3−-N removal efficiency. The NO3−-N removal efficiency of denitrifying bacterium FX-4 was improved by different concentrations of C12-HSL, and C12-HSL of 50 nmol∙L−1 significantly improved the NO3−-N removal efficiency of strain FX-4. C12-HSL at concentrations of 0, 5 nmol∙L−1, 50 nmol∙L−1, 200 nmol∙L−1, 500 nmol∙L−1, and 1 000 nmol∙L−1 were simultaneously added to the SBR activated sludge system, as well as the denitrification bacterium FX-4. The nitrogen removal performance, signal molecule concentration and microbial community structure of the system were investigated.The results showed that the synergistic effects of the two could significantly affect theNO3−-N removal performance of the reactor. The accumulation of NO3−-N in R1-R6 treated with signal molecules decreased by 20 mg∙L−1 to 50 mg∙L−1 compared with the control group R0. The consumption of NO3−-N in R3 was the highest in the reactor with 100 nmol∙L−1 C12-HSL, and the NO3−-N concentration in effluent was about 45 mg∙L−1 lower than that of R0. In addition, C12-HSL signal molecules had a significant positive effect on TN removal, and the TN removal efficiency of activated sludge system was improved more effectively with 100 nmol∙L−1 C12-HSL dosage. Signal molecule concentration change detection results showed that exogenous addition of C12-HSL could stimulate the secretion of other AHLs in the system, especially the secretion of C4-HSL in the system. The results of microbial community structure analysis showed that exogenous addition of denitrifiers FX-4 and signal molecule C12-HSL could significantly affect microbial community composition in activated sludge, accelerate microbial population succession in activated sludge, and increase the relative abundance of denitrification bacteria such as Thauera and Brevundimonas. This study can provide technical parameter reference for signal molecules as emergency methods to enhance biological nitrogen removal performance of activated sludge system.