附着剑菌对多氯联苯（PCBs）的生物吸附及生物降解机制

发布时间：2019-02-19 11:20

【摘要】：多氯联苯(polychlorinated biphenyls,PCBs)由于具有良好的阻燃性、热稳定性、化学惰性和高电阻率,曾被大量生产并被广泛运用于工业生产,又由于其具有持久性、高毒致癌性及生物积累性,成为斯德哥尔摩公约首批优先控制的12种持久性有机污染物之一。PCBs在进入环境后,会受多种环境因素的影响,在不同介质中发生一系列的转化,最后趋于平衡,其中水体PCBs污染与人类生产生活关系最为密切。本文以获得的一株PCBs降解菌为生物材料,研究了短期活体和死体菌株在不同培养时间对2,4,4'-TCB的生物去除作用并对去除条件进行优化;探究了短期活体菌株对TCB的去除机制及不同条件下的生物吸附和生物降解能力;探讨了长期菌体对TCB的生物吸附和生物降解机制,研究了活体菌株对不同氯代PCBs同系物的生物吸附和生物降解作用。具体实验结果如下:1、附着剑菌(Ensifer adhaerens R2)活菌及灭菌处理对2,4,4'-TCB均有较高的去除效率,灭菌处理去除效果更佳。R2对2,4,4'-TCB的去除可在2h内达到平衡,温度、OD值、金属离子均会影响去除效果。2、短期实验中(24h),R2活菌对溶液中2,4,4'-TCB的去除作用包括生物吸附和生物降解,生物吸附相对贡献更大;R2的灭活处理对TCB的去除机制为生物吸附,并且吸附效率高于活菌处理。R2活菌对TCB的去除在2h即可达到平衡,单因素条件下,pH值为7.5,温度为30℃,添加0.05mol/L的Ca2+、Mg2+可使活菌对2,4,4'-TCB的降解达到最优;pH值为6.0、35℃、OD为0.8、添加1mol/L的Ca2+、Mg2+处理可使活菌对2,4,4'-TCB的吸附达到最优。3、长期实验中(16d),实验前期R2活菌生物吸附所占比列更大,后期生物降解占据主导地位。菌体分泌的多糖、蛋白、脂质均参与了 TCB的吸附。菌体分泌的可溶性EPS中多糖产量随时间呈升高趋势,不溶性EPS中多糖及蛋白呈降低趋势。菌体SOD、POD活性随时间呈上升趋势,最高分别可达575.21 U/g、1052.63U/(g.min);菌体PPO活性呈先升高后平稳的趋势,最高可达2631.58 U/(g·min);菌体INT活性呈先升高后略微降低的趋势。4、探讨了活菌对不同氯代同系物的去除机制,结果表明,氯取代数越高,越易被菌体吸附,越难被降解。
[Abstract]:Polychlorinated biphenyls (polychlorinated biphenyls,PCBs) have been widely used in industrial production because of their good flame retardancy, thermal stability, chemical inertia and high electrical resistivity, and because of their persistence, high toxicity, carcinogenicity and bioaccumulation, polychlorinated biphenyls (polychlorinated biphenyls,PCBs) have been widely used in industrial production. PCBs is one of the first 12 persistent organic pollutants under priority control under the Stockholm Convention. After entering the environment, PCBs will undergo a series of transformations in different media under the influence of a variety of environmental factors. Water PCBs pollution is most closely related to human production and life. In this paper, a strain of PCBs degrading bacteria was used as biomaterial to study the biological removal effect of short term live and dead strains on 2O4O4TCB and optimize the removal conditions. The removal mechanism of TCB and the ability of biosorption and biodegradation under different conditions were investigated. The mechanism of TCB biosorption and biodegradation by long term bacteria was studied. The bioadsorption and biodegradation of different chlorinated PCBs congeners by live strains were studied. The experimental results are as follows: 1. The removal efficiency of active bacteria and sterilizing bacteria from (Ensifer adhaerens R2 is higher than that of sterilizing treatment, and the removal efficiency of sterilizing treatment is better, and the removal of TCB by R2 can reach equilibrium within 2 hours. Temperature, OD value and metal ions all affected the removal efficiency. 2. In the short-term experiment (24 h), the removal effects of R2-live-bacteria on the removal of 2C4O4TCB in solution included biosorption and biodegradation, and the relative contribution of biosorption was greater. The removal mechanism of TCB by the inactivation treatment of R2 was biosorption, and the adsorption efficiency was higher than that of the live bacteria treatment. The removal of TCB by R2 could reach equilibrium within 2 hours. Under the condition of single factor, the pH value was 7.5 and the temperature was 30 鈩，

本文编号：2426454