【作者】 吴小莉；

【导师】 余健；

【作者基本信息】 湖南大学 ， 市政工程， 2008， 硕士

【摘要】 本文在综述国内外文献的基础上,首次以摇瓶实验的形式对1,4-二氯萘和2,6-二氯萘的微生物降解进行了系统的研究。实验以垃圾渗滤液处理池的活性污泥为菌源,筛选出了一株细菌HY, 16S rRNA同源性分析该菌为假单胞菌属(Pseudomonas sp)。在25℃、180r/min、pH=7、OD600=0.25、初始浓度10mg/L、20、50mg/L条件下,10、20mg/L浓度的1,4-二氯萘在2天和5天内可完全降解,但初始浓度为50mg/L 1,4-二氯萘的生物降解在80h后几乎停滞,降解率只有40%;且实验过程中光密度均逐渐下降,细菌无生长现象。而投加萘(50mg/L)时,50mg/L的1,4-二氯萘可在300h完全降解,但是在降解的前8h存在萘的竞争抑制作用。进行了以肉汤培养基富集菌液对1,4-二氯萘的降解对比实验,确定1,4-二氯萘不支持微生物生长,HY菌对1,4-二氯萘的降解属共代谢范畴, HY菌对1,4-二氯萘的降解是以萘的诱导为前提的。HY菌不能共代谢2,6-二氯萘,静息细胞实验也证实了该菌不能产生降解2,6-二氯萘的酶系。结合1,4-二氯萘、1-氯萘、2-氯萘的生物降解的实验结果分析,认为位于不同苯环上的氯取代不利于微生物降解。对不存在初级基质条件下, 1,4-二氯萘的降解实验数据进行了动力学研究, 10、20mg/L的生物降解符合一级反应动力学,一级反应速率常数分别为0.0626、0.0265-1,半衰期分别为15.97h、37.74h,50mg/L的生物降解介于零级反应和一级反应之间;采用不存在初级基质条件下的三种共代谢模型对1,4-二氯萘的微生物降解进行非线性拟合,结果显示模型3对三种浓度下1,4-二氯萘的生物降解拟合较好,其对应的表观生物量转化浓度Tc b分别为0.1932、0.2869、0.2789。利用气相色谱质谱联用仪(GC-MS)对1,4-二氯萘降解的中间产物进行了定性分析,检测到了二氯代水杨酸、环氧化氯萘、二氯代水杨醛、二氯代萘酚,硅烷衍生化样品的GC-MS分析显示,产物中可能还还存在二羟基二氯代萘,并据此推测1,4-二氯萘生物降解的途径为5,6位或7,8位加单氧后羟基化,苯环开裂后再生成氯代水杨酸。更多还原

【Abstract】 On the basis of summarizing the related references home and abroad, a series of shake flask experiments had been conducted to study the biodegradation of 1,4-dichloronaphthalene(1,4-DCN) and 2,6-dichloronaphthalene(2,6-DCN). We isolated a strain named HY from the actived sludge at a land fill leachate treatment plant, the strain had been identified as Pseudomonas sp. by the analysis of 16S rRNA . under the condition of 25℃、180r/min、pH=7、OD600=0.25、initial concentration 10、20、50mg/L, The strain were able to biodegraded 10mg/L 1,4-DCN in 48h and 20 mg/L 1,4-DCN in 120h, but the biodegradation which intial concentration was 50mg/L almost ceased after 80h,and degradation rate was only 40%; in these experiments photodensity OD600 all decreased gradually,but when naphthalene existed, 50mg/L1,4-DCN could be totally degraded in 300h.however there was a acclimatization phase of 8h because of competition inhibition effect from naphthalene . by comparing with degradation experiment by strain which grown on broth medium,we concluded that HY strain should cometabolize 1,4-DCN ,and biodegradation take the naphthalene induction as the premise. The HY strain could not cometabolized 2,6- DCN,and through resting cell experiment ,we determined HY strain could not produce enzymatic system which could degrade 2,6-DCN, unified the conclusion of 1-chloronaphthalene(1-CN),2-chloronaphthalene(2-CN), 1,4-DCN biodegradation experiments ,we concluded that chlorine substitution located on two benzene rings does not favor the microbial degradation.we also did the research on the kinetics model of 1,4-DCN degradation when there is not primary substance,biodegradation which 1,4-DCN concentration was 10、20 mg/L could be expressed by first-grade equation,first reaction rate constant was 0.0626、0.0265h-1, the half life of 1,4-DCN was 15.97h、37.74h, respectively .biodegradation which 1,4-DCN concentration was 50mg/L accorded to equation between first-grade equation and first-grade.when initial concentration of 1,4-DCN was 10、20、50mg/L,.The results of non-line curve fitting indicated 10、20、50 mg/L 1,4-DCN biodegradation could be expressed by model 3, its corresponding apparent biomass transformation density is 0.1932、0.2869、0.2789, respectively. we analyzed qualitatively biodegradation intermediates by using GC-MS, and found dichlorosalicylic acid、epoxydichloronaphthalene、dichlorosalicylal、dichloronaphthol, the rusult of silanization sample analyzed by GC-MS was there were dihydroxydichloronaphthalen possibly,at last we deduced the possible degradation route of 1,4-DCN : 6 , 7 or 7 , 8 monooxygen oxidation reaction firsrly,and then hydroxylation,at last benzene ring cracks and brings dichlorosalicylic acid.更多还原