十氯联苯降解菌的分离、降解机理及降解产物的研究

发布时间：2018-01-07 16:36

本文关键词：十氯联苯降解菌的分离、降解机理及降解产物的研究　出处：《长安大学》2015年硕士论文　论文类型：学位论文

【摘要】：十氯联苯是多氯联苯中的一种,具有难降解、高毒性、半挥发、生物蓄积的特性。对于多氯联苯的处理技术,国内用的较多且成熟的有高温焚烧及化学催化。微生物降解方法是近年来研究的热点。已有研究报道关于好氧降解菌对低氯代多氯联苯的降解机理,但低温、厌氧环境降解高氯代多氯联苯却少有报道。本实验以高毒、难降解的十氯联苯为研究对象,从渭河陕西中段西安草滩处所取的渭河底泥为微生物的菌源,经过对自然微生物的培养、驯化,分离出能够以十氯联苯为唯一碳源的三株降解菌,分别命名为L1、L2、L3,通过相同条件下不同菌株降解率的比较,得出L1菌株对十氯联苯的降解率为76.50%,L2菌株对十氯联苯的降解率为64.67%,L3菌株对十氯联苯的降解率为53.82%,由此认为L1菌株为优势降解菌,对其革兰氏染色后显紫色,微生物为杆状。通过接触酶及甲基红两种生化鉴定结果可知,L1菌株降解过程中不产生接触酶,但是有有机酸生成。以培养液pH、十氯联苯初始浓度、微生物接种量为影响因素,研究这几种因素对优势降解菌L1降解效率的影响,得出优化的微生物生长条件:pH值为7,十氯联苯初始浓度为1.5mg/L,微生物接种量为8m L。通过利用GCMS对十氯联苯降解菌的降解产物进行定性分析,推测厌氧条件下微生物先将十氯联苯还原为低氯代的多氯联苯,相应降解酶的产生使得低氯代的多氯联苯化合物中苯环开环,经过氧化还原、消去等反应进一步分解生成低毒或无毒的有机物。本实验在接近渭河环境的条件下驯化、筛选出一种厌氧菌株,且通过实验确定了其优化的降解条件,为生物降解十氯联苯提供了有价值的信息;为菌剂的制备以及从污染源头进行预防治理工程应用的可能性、可行性及运行工况提供了参考。
[Abstract]:Chlordated biphenyls are one of the polychlorinated biphenyls (PCBs), which are difficult to degrade, highly toxic, semi-volatile and bioaccumulative. In recent years, the methods of microbial degradation have been the focus of research. It has been reported on the degradation mechanism of aerobic bacteria to low chlorinated polychlorinated biphenyls (PCBs), but at low temperature. The anaerobic degradation of high chlorinated polychlorinated biphenyls (PCBs) was rarely reported. In this experiment, chlordated biphenyls, which are highly toxic and difficult to degrade, were used as the research object. The sediment of the Weihe River was taken from the Caotan area of Xi'an in the middle section of the Weihe River as the microbial source. Through the cultivation and domestication of natural microorganisms, three strains of biodegradable bacteria with chlordated biphenyls as the sole carbon source were isolated and named L1 / L2 / L3, respectively. The degradation rates of different strains were compared under the same conditions. The results showed that the degradation rate of chlorinated biphenyls of strain L1 was 76.50 and that of strain L2 was 64.67 and that of strain L3 was 53.82%. It is concluded that L1 strain is the dominant biodegradable strain, and its Gram stain shows purple and microorganism is rod-like. The results of contact enzyme and methyl red biochemical identification show that there is no contact enzyme in the degradation process of L _ 1 strain. But there was organic acid formation. With the pH of culture medium, initial concentration of chlordated biphenyls and inoculation amount of microorganism as the influencing factors, the effects of these factors on the degradation efficiency of dominant degrading bacteria L1 were studied. The optimum microorganism growth conditions are as follows: the pH value is 7 and the initial concentration of chlorinated biphenyls is 1.5 mg / L. The microbial inoculation amount was 8 mL. The degradation products of chlorinated biphenyls were qualitatively analyzed by GCMS. It was inferred that under anaerobic condition the chlorinated biphenyls would be reduced to low chlorinated polychlorinated biphenyls (PCBs). The corresponding degradation enzymes make benzene ring open and redox in low chlorinated polychlorinated biphenyls (PCBs). Elimination reaction further decomposed to produce low-toxic or non-toxic organic matter. This experiment was domesticated near the Weihe River environment to screen out an anaerobic strain and determined the optimal degradation conditions through the experiment. Provides valuable information for biodegradation of chlorinated biphenyls; It provides a reference for the preparation of bacteria agent and the possibility, feasibility and operation condition of prevention and treatment engineering from the source of pollution.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X172

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