【作者】 付晓；

【导师】 陈珊；

【作者基本信息】 东北师范大学 ， 微生物学， 2009， 硕士

【摘要】 聚己内酯(Poly-Caprolactone,PCL),一种可完全降解的半结晶型脂肪族聚酯,近来在医药、农业、环保等方面获得广泛的关注。但其生物降解性研究目前报道较少。本论文通过采集活性污泥样品,并进行分离、筛选,获得一株可高效降解PCL的细菌菌株DS0601-fx。通过菌株和菌落的形态学观察以及菌株的生理生化特性试验和16S rDNA序列分析比对,初步鉴定该菌株属于假单胞菌属(Pseudomonas sp.)。在以PCL为唯一碳源的培养基中培养菌株DS0601-fx,对其生长规律、PCL粉末和PCL膜的降解行为进行观察研究,发现DS0601-fx可以在70h以内将PCL膜完全降解,其降解速率趋势与菌株生长趋势趋于一致。对PCL粉末为唯一碳源的液体培养基进行了优化,发现用PCL粉末培养90h后菌株可以分泌大量蛋白,蛋白具有对PCL的降解能力,对DS0601-fx菌株产生的PCL解聚酶进行进一步分离纯化,通过Sephacryl S-100层析后分离出一种PCL解聚酶。酶的比活力达到900.24 u/mg,纯化倍数为14.24,酶活回收率为2.64%。对PCL膜降解的SEM照片进行观察,发现解聚酶引起的PCL膜降解存在一定规律,即由表层平面降解到深层立体降解;从非结晶区快速降解到结晶区缓慢降解。菌株DS0601-fx不仅可以在PCL唯一碳源培养基中良好生长,也可以在其他生物可降解材料PHB和PLA培养基中稳定生长并分泌相应的解聚酶。更多还原

【Abstract】 Poly-caprolactone(PCL) is a biocompatible ,biodegradable and semi- crystalline polyester proposed for a wide variety of applications in the medical industry, extractive industry and environmental protection in recently years. The biodegradability of PCL has been studied but not reported a lot about research of the PCL de-polymerase.The strain DS0601-fx which can degrade PCL efficiently was isolated from the soil . According to morphological observation、the physiological and bio-chemical characteristics and 16S rDNA analysis, the strain was identified to belong to Pseudomonas.The study of the strain growth regulation on the culture medium which use PCL as the sole carbon and energy showed as follows: DS0601-fx can degrade PCL films completely in 70 hours.The trend of the degrade speed is inosculate to the strain growth regulation.Meliorate the proportion of PCL in culture medium which use PCL as the sole carbon and energy source and found DS0601-fx can abundantly produce the PCL de-polymerase in 90 hour by PCL granule medium. An extra-cellular PCL de-polymerase was purified according to gel filtration technique by Sephacryl S-100. The specific activity of the purified enzyme was 14.24-folds and the recovery yield was 2.64%.The degradation of PCL films is studied by SEM photos and found there are some formulae in it .The degradation of PCL happened in the surface layer first then deep-seated place. Synchronously the non- crystalline parts degraded rapidly and the crystalline parts slowly degraded at last.The strain DS0601-fx which can efficient degrade not only PCL but also other biodegradable polyester such as PHB and PLA.更多还原