低温耐盐硝基苯降解菌的筛选及降解性特性研究

发布时间：2018-01-06 09:20

本文关键词：低温耐盐硝基苯降解菌的筛选及降解性特性研究　出处：《辽宁大学》2016年硕士论文　论文类型：学位论文

【摘要】：硝基苯是重要的化工材料,其经磺化、硝化等反应的产物被广泛应用于制造苯胺、医药、炸药、肥皂及合成橡胶等产品,且主要用于制造苯胺。由于硝基苯是中等毒性物质,可通过呼吸系统或食物链进入人体,对人体的肝、脾、肾及神经系统产生毒害作用,并可引起“三致”。利用微生物来改善水环境质量,同时解决了物理法残留的二次污染问题及化学法处理成本高的难题。我国北方地区冬季寒冷致使城市污水处理系统中活性污泥活性较低,微生物代谢速率受到抑制,限制了微生物降解硝基苯的能力。并且硝基苯污水中除了含有硝基苯及苯胺在内的有毒污染物外,还含有大量对微生物生命活动产生抑制作用的无机盐(如C1、Na+、Ca2+和SO42-等)。因此获得性能良好的低温耐盐硝基苯降解菌,以期为冬季北方地区硝基苯污水处理系统中硝基苯的有效去除提供科学依据及技术支撑。从沈阳市北部污水处理厂曝气池中采集活性污泥,并通过对其进行富集培养、硝基苯降解能力驯化、低温耐盐能力驯化后,分离筛选出16株有降解硝基苯能力的菌株,其中5株菌株降解能力较为显著,其硝基苯降解率均大于40%,分别命名为X1、X3、X7、X11和X14。初筛得到的5株菌株进行进一步的复筛试验,发现在不同硝基苯浓度条件下菌株X7的生长及硝基苯降解性能均优于其他4株菌株,因此确定菌株X7为目标菌株。通过菌株X7特有的形态特征及常规的生理生化指标结果,并结合16S rDNA基因测序,确定菌株X7为气味类香菌(Myroides odoratus)。菌株X7的降解特性试验表明,菌株X7降解硝基苯的最适环境温度为15℃,最适pH值为7.0,最适摇床转速为150 rpm,最适初始接种量为10%,最适宜盐度范围为1.0～3.0%,当硝基苯初始浓度为150 mg/L时,降解率可达到51.50%,最大耐受硝基苯浓度可达350 mg/L。当分别加入葡萄糖作为辅助碳源和蛋白胨作为辅助氮源时,对菌株X7降解硝基苯起到了一定的促进作用,硝基苯降解率也分别提高到了58.92%和60.24%,但乙酸铵作为共代谢基质加入时,对菌株X7降解硝基苯产生了抑制作用。菌株X7的动力学试验表明,当硝基苯初始浓度低于120 mg/L时,硝基苯浓度还不能够为菌株X7生长代谢提供充足的碳源,此时菌株X7的降解动力学符合零级反应动力学方程,相关系数为0.9874～0.9925。当硝基苯初始浓度高于120 mg/L时,硝基苯对菌株的毒害作用表现明显,菌株X7的降解动力学符合Andrews底物抑制模型,动力学参数：μmax=1.32684,Kg=37.75747,Kt=110.63896。
[Abstract]:Nitrobenzene is an important chemical material, the sulfonation reactions such as nitration products, is widely used in the manufacture of aniline, pharmaceuticals, explosives, soap and synthetic rubber products, and is mainly used in the manufacture of aniline. The nitrobenzene is moderately toxic substances, can enter the body through the respiratory system or the food chain, the body's liver, spleen, kidney and nervous system toxicity, and may cause the "three letter". To improve the water environmental quality by microorganism, and solve the physical method of residue two pollution problems and chemical treatment of the problem of the high cost. In the North China region in winter because of the cold activated sludge of city sewage treatment system is low. Microbial metabolic rate was inhibited, limiting the ability of microbial degradation of nitrobenzene and nitrobenzene wastewater. In addition to toxic pollutants containing nitrobenzene and aniline, and also contains a lot of microbial life Inorganic salt inhibited the activities (such as C1, Na+, Ca2+ and SO42-). Therefore, obtain good performance of low temperature salt tolerant Nitrobenzene Degrading Bacteria, in order to provide scientific basis and technical support and effective removal of nitrobenzene in winter in northern area of nitrobenzene in wastewater treatment system. Collected from the activated sludge of Shenyang Northern Sewage Treatment Plant aeration in the pool, and through the enrichment, domestication of nitrobenzene degradation ability, low salt tolerance after domestication, isolated 16 strains capable of degrading nitrobenzene, of which 5 strains degradation ability is significant, the degradation rate of nitrobenzene is greater than 40%, which were named X1, X3, X7, X11 and X14. the screening of 5 isolated strains were screened by further testing, found superior in growth and nitrobenzene degradation performance of different nitrobenzene concentration under the conditions of strain X7 of the other 4 strains, the strain X7 was identified as target bacteria The morphological characteristics of the strains X7 strains. The unique and common physiological and biochemical indexes of the results, combined with 16S rDNA gene sequencing, strain X7 was identified as Myroides odoratus (Myroides odoratus). The test shows that the degradation characteristics of strain X7, strain X7 degrading the optimum environment temperature is 15 DEG C, the optimum pH value was 7. And the optimum rotation speed was 150 rpm, the optimum initial inoculation amount was 10%, the optimum salinity ranged from 1 to 3%, when the initial concentration of nitrobenzene is 150 mg/L, the degradation rate can reach 51.50%, the maximum tolerated concentration of nitrobenzene can reach 350 mg/L. when glucose were added as auxiliary carbonsource peptone as nitrogen source and auxiliary when, to a certain extent of strain X7 degradation of nitrobenzene, nitrobenzene degradation rate were increased to 58.92% and 60.24%, but ammonium acetate as co metabolism substrate is added to inhibit degradation of nitrobenzene. Strain X strain X7 The test shows that the dynamics of 7, when the nitrobenzene concentration lower than 120 mg/L, the concentration of nitrobenzene is not able to provide sufficient carbon source for the strain X7 growth and metabolism, the degradation kinetics of strain X7 with zero order kinetics equation, the correlation coefficient is 0.9874 ~ 0.9925. when the initial concentration of nitrobenzene was higher than 120 mg/L, the toxic effects of nitrobenzene the strain is obvious degradation kinetics of strain X7 with Andrews substrate inhibition model, kinetic parameters: max=1.32684, Kg=37.75747, Kt=110.63896.

【学位授予单位】：辽宁大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X172;X703

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