【作者】 巩继贤；

【导师】 张健飞；

【作者基本信息】 天津工业大学 ， 纺织化学与染整工程， 2004， 硕士

【摘要】 聚对苯二甲酸乙二酯（PET）是通用的高分子材料之一，广泛应用于各个领域。为了对PET进行减量处理和表面改性及能有效地处理PET废弃物，人们开始了对PET降解菌及微生物对PET降解性能的研究。而由于PET具有疏水性而且结构致密，现有的菌种都不能对其进行生物降解，所以只能通过人工培养，筛选出PET的高效降解菌。 因为对苯二甲酸二乙酯（DTP）与PET的基本单元结构上相似，因此本实验以DTP为模拟物来培养和驯化PET的降解菌，并对其降解性能进行研究。另外，作为一种化学试剂DTP本身也是一种环境荷尔蒙，对生物体内分泌系统有扰乱和破坏作用。 本课题从对DTP有降解作用的混合菌悬液中分离出5株纯种菌，并从中筛选出对DTP降解作用最好的菌株F₄。经革兰氏染色试验判定菌株F₄为革兰氏阳性菌，经氧化酶和过氧化氢酶试验判定菌株F₄为好氧菌。 我们对菌株F₄的生长特性进行了试验。结果表明在培养基M₅中菌株F₄的生长情况最好，远远好于培养基M₁，M₂和M₃中的生长。DTP浓度对菌株F₄的生长速率和生长总量均有影响，DTP的浓度越高，菌体的总量就越大；在较高DTP浓度下菌株F₄的生长速率也大于在低浓度下的生长速率。另外，作为代谢产物的对苯二甲酸对菌株F₄的生长有一定的抑制作用。菌株F₄的最佳生长温度是30℃，最佳pH值为7.5，并且菌株F₄在振荡情况下的生长情况要好于静止条件下培养的。 本课题还对菌株F₄降解DTP的影响因素及其动力学进行了分析。菌株F₄降解DTP的最适温度为30℃；最适pH值为7.5；菌株F₄对DTP的降解适合于振荡培养，且振荡速率越高降解效果越好；随降解液中接种量的增加，DTP的降解率也增大。菌株F₄对DTP的降解符合一级动力学特征。 为了对DTP及PET纤维的生物降解进行深入探讨，我们提取了菌株F₄的胞外和胞内酶的粗酶液，并进行研究。初步认定菌株F₄的DTP降解酶主要定域于胞内。提取酶E_内对DTP的催化降解反应的米氏常数K_m为0.626g／L，即3.8×天津工业大学硕士研究生学位论文10一3mol/L。提取酶E。对DTP降解的最适pH值为7一8，最适合的温度为30℃左右。 为与提取酶进行比较，本课题还用Sigma公司的脂肪酶进行与提取酶同样的试验。Sigma脂肪酶对DTP的催化降解反应的米氏常数长。为7.82留L，即4.7X10一Zmol/L;最适pH值为7一8，最适合的温度为30℃左右。由Km可知，提取酶E}。对DTP的亲和力大于Sigma脂肪酶，它更适合于DTP的降解。 本课题分别用Sigma脂肪酶、菌株F4及其提取酶对PET纤维进行了降解实验。菌株F4对PET纤维确有降解作用。Sigma脂肪酶对PET纤维的降解作用十分微弱。单纯用提取酶E外和E内对PET纤维进行降解，基本上都没有什么效果;而提取酶E外和E内的混合物对PET纤维则有一定的降解效果。提取酶的混合物对PET纤维的降解效果比菌株F4的降解效果好许多。 尽管对PET纤维的生物降解效果还不是很理想，但目前的研究成果为今后的进一步研究奠定了基础。更多还原

【Abstract】 Poly(ethylene terephthalate) (PET) has been used widely in the world. In order to disposal PET waster or modify the surface of PET fiber, biodegradation of PET fiber has been studied. Because of its hydrophobic nature and its compact structure PET can not be degraded by microorganisms in environment, so we have to screen and isolate PET degrading microorganisms via experiment.In this paper we use DTP as simulacrum to find stronger PET degradation microorganisms. In addition, DTP itself is an environmental hormone.Five strains have been obtained, and the strongest DTP degradational strain has been isolated which was named F4. The characteristics of F4 has been studied. M5 is the best favorite medium to F4, and the higher concentration of DTP in medium, the faster F4 grow. To some extent TA is an inhibitor in the growth of F4. The optimum temperature of the growth of F4 is 30掳C and the optimum pH is 7.5.The influence factor of DTP degradation by F4 has been investigated. The optimum temperature of degradation is 30 C and the optimum pH is 7.5.The effect of degradation in shaking is bigger than motionless and the effect increase when inoculation rise. The degradation kinetic of DTPaccords with Monod equation.The crude enzyme extracted from F4 has been researched. The intracellular enzyme has more effect than extra cellular enzyme. The optimum temperature and pH of the crude enzyme activity to DTP were 30掳C and 7~8 respectively.The Michaelis-Menten’s constant (Km) of DTP enzymic degradation was 3.8 m mol/L.The control experiments have been done with Sigma esterase. The optimum temperature and pH of the crude enzyme activity to DTP were 30掳C and 7~8.The Michaelis-Menten’s constant (Km) of DTP enzymic degradation was 47 m mol/L.In this paper Sigma esterase, F4 and its intracellular enzyme have been utilized in the degradation of PET fiber .The result showed that F4 and Sigma esterase have some effect to PET fiber, but this effect is very weak. There is no effect using intracellular enzyme and extra cellular enzyme to degrade PET fiber separately, but the mixture of intracellular enzyme and extra cellular enzyme has some effect.The experiment in this paper established a good foundation for the further research.更多还原