果糖共代谢强化功能菌群/菌株降解活性黑5效能差异及机制比较

Comparison of efficiencies and mechanisms of functional flora/strain in degradation of reactive black 5 enhanced by fructose co-metabolism

摘要:

【背景】偶氮染料及其降解产物对生物具有高毒性和“三致”效应，利用共代谢强化纯培养细菌菌株或共培养混合菌群降解偶氮染料去除效能是一种环境友好型方法，但针对共基质调控下菌群/菌株的效能差异机制比较研究有待深入。【目的】考察果糖作为共基质强化功能菌群DDMZ1和功能菌株DDMZ1-1 (经鉴定属于Burkholderia sp.)降解脱色活性黑5 (reactive black 5, RB5)的效能差异机制。【方法】优化功能菌群/菌株培养条件，对果糖共代谢强化功能菌群/菌株的脱色性能及偶氮还原酶活性进行测定，通过液相色谱-飞行时间串联质谱联用仪(LC-TOF-MS)及植物毒性实验对RB5降解产物进行分析鉴定及毒性评估，并考察比较功能菌群/菌株对不同结构染料的广谱脱色性能。【结果】功能菌群DDMZ1和功能菌株Burkholderia sp. DDMZ1-1在优化条件下(pH 5.5, 37 ℃)对RB5的去除效率分别为79%和73%，而且功能菌群对高盐环境具有更强的适应优势。果糖的添加能够显著提升功能菌群/菌株对不同初始浓度RB5的脱色性能，特别是针对200 mg/L RB5的去除效率相较于不添加果糖的样品分别提升了近21%和27%。样品FRU200 (添加果糖)反应24 h后显著刺激功能菌群/菌株分泌胞外偶氮还原酶进而增强其活性。LC-TOF-MS分析显示，RB5在功能菌群DDMZ1果糖共代谢体系中被生物降解成更多分子量低、结构简单的代谢产物。功能菌群/菌株体系中RB5降解产物的植物毒性在果糖共代谢作用下均显著降低。功能菌群DDMZ1相较于功能菌株Burkholderia sp. DDMZ1-1对不同结构类型染料具有更强的广谱脱色性能。【结论】功能菌群DDMZ1利用果糖共代谢强化活性黑5的去除效能、功能酶活、产物脱毒作用均显著优于功能菌株Burkholderia sp. DDMZ1-1，为共基质生物强化技术在含偶氮染料废水领域的应用提供理论基础。

关键词:果糖;功能菌群/菌株;活性黑5;降解产物;毒性评估

Abstract:

[Background] Azo dyes and their degradation products are highly toxic and have carcinogenic, teratogenic, and mutagenic effects on organisms. Using co-metabolism to enhance the degradation and removal efficiency of azo dyes by pure cultured bacterial strain or co-cultured flora is environmentally friendly, whereas the comparative study on different efficiencies and mechanisms of bacterial flora/strain under co-substrate regulation needs to be further studied. [Objective] To investigate the efficiencies and mechanisms of functional flora DDMZ1 and strain DDMZ1-1 (identified as Burkholderia sp.) in the degradation and decolorization of reactive black 5 (RB5) enhanced by fructose as a co-substrate. [Methods] The culture conditions of functional flora/strain were optimized, and the decolorization performances and azoreductase activities of functional flora/strain enhanced by fructose co-metabolism were determined. The identification and toxicological assessment of RB5 degradation products were performed by the liquid chromatography/time-of-flight/mass spectrometry (LC-TOF-MS) and phytotoxicity test. The broad-spectrum decolorization performances of functional flora/strain on decolorizing dyes with varied structures were compared and investigated. [Results] The removal efficiencies of RB5 by the functional flora DDMZ1 and Burkholderia sp. DDMZ1-1 under the optimal conditions (pH 5.5, 37 ℃) were 79% and 73%, respectively, and the functional flora exhibited stronger adaptive advantages to the high-salinity environment. The addition of fructose significantly stimulated the decolorization performance of functional flora/strain to RB5 with different initial concentrations. Compared with the flora/strain samples without fructose, those with fructose increased the removal efficiencies of 200 mg/L RB5 by nearly 21% and 27%, respectively. The sample FRU200 (with fructose) significantly stimulated functional flora/strain to secrete extracellular azoreductases after 24 h, thus enhancing the enzyme activity. LC-TOF-MS analysis indicated that RB5 was biodegraded into various metabolites with low molecular weights and simple structures in the fructose co-metabolic system of functional flora DDMZ1. The phytotoxicity of RB5 degradation products in the flora/strain system was significantly reduced via fructose co-metabolism. Compared with Burkholderia sp. DDMZ1-1, the functional flora DDMZ1 exhibited a stronger broad-spectrum degradation ability to dyes with varied structures. [Conclusion] Compared with Burkholderia sp. DDMZ1-1, the functional flora DDMZ1 has better removal efficiency, functional enzyme activity, and product detoxification of RB5 enhanced by fructose co-metabolism. This paper provides a theoretical basis for the application of co-substrate bioaugmentation technology in the treatment of wastewaters containing azo dyes.

Key words:fructose;functional flora/strain;reactive black 5;degradation products;toxicity assessment