Breeding Of Aspergillus Versicolor To Degrade PBS And The Research Of PBS Depolymerase

Poly(butylene succinate) got into the materials research region in the 1990s, and quickly become one of hotspot stuff of biodegradable plastics research. The source of synthesis material can be petroleum resource, and it also can be got by fermentation of biotic resources. PBS biodegradable plastic is used broadly; it is useful in casing, dinnerware, cosmetic case, drug bottle, agriculture film, pesticide, fertilizer slow release stuff, and high molecular material region. Compare to other biodegradable plastics, PBS have peculiar advantages in thermal property and process property. Therefore, science and technology and industrial community pay high attention on it.The aim of this work is to try to find out the microorganisms from nature which can be able to degrade PBS, and the domesticated and mutagenic degradation strain can degrade PBS quickly. PBS depolymerase has been purified and some primary analysis has been done on it for lying the theoretical and practical foundations of PBS application.The main results obtained from this work are as follows:1. Four kinds of strains able to degrade PBS were isolates from the mud which was discharged by No.3 Petrol-Company of Fushun, coded as XH0501,XH0502,XH0503,XH0504. One kind of fungi which have a fast degradation rate, coded as XH0501, were identified preliminarily: XH0501 belongs to Aspergillus versicolor.2. The Aspergillus versicolor XH0501, a strain of degrading PBS, was mutated by UV mutagenesis compound LiCl mutagenesis and microwave mutagenesis. Through screening a lot of mutants with the method of culture filtrate, one mutant which has stable character of heredity has been obtained, coded as XH0501-a. The activity of the enzyme which is abstracted from XH0501-a is 38.89% more than that is from XH0501.3. Some research has been done on the PBS depolymerase which is obtained from XH0501-a. The final purified enzyme represented the 12.07% recovery and the 12.26-fold purified protein with a molecular weight of 44.7kD.4. The most suitable reaction temperature of this PBS depolymerase is 40℃and pH is 8.6. Below temperature 30℃and between pH 8.4～9.0, the enzyme is stable. Ca²⁺ and Fe²⁺ can active the enzyme, but Cu²⁺ and Hg²⁺ will make it lose activation.5. The degraded product with PBS depolymerase was monomer succinic acid butanediol ester analyzed by using mass spectrometer.6. The degradation of PBS films was monitored by using SEM. Before degradation, the film was slide. But there are obvious holes on the film after degradation.