氨氮胁迫下E.coli单菌运动行为与成膜能力研究

Movement behavior and biofilm formation ability of E.coli under ammonia nitrogen stress

生产生活废水中一定质量浓度的氨氮对细菌活性具有抑制作用。从个体水平观察氨氮胁迫下E.coli在液固界面的旋转运动行为,并将其同氨氮胁迫下E.coli电子传递体系活性(ETSA)、成膜能力进行关联分析,以探究揭示氨氮胁迫下细菌运动行为的规律及其与成膜能力的联系。结果表明,高、低质量浓度组氨氮胁迫均对细菌运动产生抑制,细菌平均旋转周期随抑制质量浓度增加呈逐渐增大趋势。25 mg/L、50 mg/L、75 mg/L、200 mg/L、300 mg/L、400 mg/L和500 mg/L氨氮胁迫5 min后,E.coli平均旋转周期分别增长为未受抑制时的2.58倍、4.17倍、5.16倍、6.77倍、7.50倍、8.44倍和14.02倍。同时,在氨氮胁迫下,细菌平均旋转周期分别与细菌ETSA、成膜能力呈负相关(R^(2)=0.7797)与正相关(R^(2)=0.7456)。研究表明氨氮胁迫抑制细菌ETSA是氨氮抑制细菌运动行为的一种可能机制,一定质量浓度氨氮抑制细菌运动的同时还促进细菌生物膜形成。这些发现为废水生物处理中细菌在氨氮胁迫环境中的运动行为和成膜情况提供了理论参考,对人工调控促进废水生物膜法中反应器快速挂膜和启动具有一定的指导意义。

A certain concentration of ammonia nitrogen in the production and domestic wastewater can inhibit the activity of bacteria.However,the movement behavior and the biofilm formation ability of single bacteria under ammonia nitrogen stress are not clear.In this paper,the rotation behavior of E.coli at the liquid-solid interface under ammonia nitrogen stress was observed at the individual bacteria level,and its correlation with the activity of E.coli electron transport system(ETSA)and the biofilm formation ability under ammonia nitrogen stress was analyzed to explore the rule of bacterial movement behavior under ammonia nitrogen stress and its relationship with film-forming ability.The results showed that the bacteria movement was inhibited by high and low concentrations of ammonia nitrogen stress,and the average rotation period of bacteria increased with the increase of ammonia nitrogen concentration.After 5 min of ammonia nitrogen stress of 25 mg/L,50 mg/L,75 mg/L,200 mg/L,300 mg/L,400 mg/L,and 500 mg/L,the average rotation period of E.coli increased by 2.58,4.17,5.16,6.77,7.50,8.44,and 14.02 times as that of the uninhibited group,respectively.Besides,under ammonia nitrogen stress,the average rotation period of bacteria was negatively correlated with the activity of ETSA and the biofilm formation ability of E.coli(R^(2)=0.7797)and positively correlated with that of E.coli(R^(2)=0.7456).The results showed that the inhibition of ETSA under ammonia nitrogen stress was a possible mechanism of the inhibition of bacterial motility.A certain concentration of ammonia nitrogen inhibited bacterial motility and promoted bacterial biofilm formation.These findings provide a theoretical reference for the movement behavior and biofilm formation of bacteria in wastewater biological treatment under ammonia nitrogen stress.The results of this experiment also have some guidance significance for the artificial regulation and control to promote the rapid membrane hanging and start-up of the reactor in the wastewater biofilm process.