Breeding Of Penicillium Sp. To Degrade PCL And The Research Of PCL Depolymerase

Poly caprolactone(PCL) produced by petroleum synthesis is an aliphatic polyester, and is easily decomposed by microbiology or enzyme in nature with the final productof CO2 and H2O. At present, PCL, as a novel biomaterial, has many potential uses in a wide range of medical, industrial and agricultureal applications.The aim of this work is to try to find out the microorganisms which can be able to degrade PCL ,and to lay the theoretical and practical foundations of PCL application by studying their fundamental properties relative to PCL degradation, investigating the biochemistry characteristics of PCL depolymerase and degradation process.The main results obtained from this work are as follows:1. Four kinds of strains able to degrade PCL were isolates from different areas and ecological environments, coded as YD0401,YD0402,YD0403,YD0404. One kind of fungi, coded as YD0401, were identified preliminarily: YD0401 belongs to Penicillium.2. The penicillium sp. YD0401, a strain of degrading PCL, was mutagenized by UV treatment. Through screening a lot of mutants with the method of transparent zones and culture filtrate, best two ones were obtained with high–yield of stable PCL depolymerase, coded as YD0401-Ae and YD0401-Bc.3. The degradation rate of PCL film by the original one can be classified into the type for whole degradation process: slow-constant-fast,while the two YD0401-Ae and YD0401-Bc muntants was slow-fast-slow.4. When the enzyme activity of the original one and the two muntants were surveyed with their daily crude enzyme, two highest enzyme peak production were found in 48h and 120h.The enzyme activity of the YD0401-Ae and YD0401-Bc muntants were 32.1%,41.86 % and 35.8 %,31.4% higher than the original one at two highest enzyme peak production respectively.5. Comparative study on the basic enzyme property of the PCL depolymerase between the YD0401-Ae mutants and the original one. The optimum temperature and pH of the YD0401-Ae mutants and the original one was 20℃and 8.6.6. The degraded product with PCL depolymerase was monomerε-hydroxy caproic acid analyzed by using mass spectrometer.7. The degradation process of PCL films was monitored by using SEM.It was shown that PCL degradation occurred firstly in the amorphous part of PCL and then in the crystalline part. But the degradation rate of the crystalline part was slow.