【作者】 张颖；

【导师】 陈坚；

【作者基本信息】 江南大学 ， 发酵工程， 2006， 博士

【摘要】 聚乙烯醇(PVA)在纺织工业中被广泛用作上浆剂。经PVA上浆的棉织物必须经过退浆处理,以增加棉织物对水的吸收性。目前常用的退浆方法是使用热水在棉织物表面洗脱PVA,有时使用氧化剂如NaBrO2等,这就导致纺织厂排出的废水中含有大量的PVA和氧化剂。如果能将PVA降解酶运用于纺织工业的退浆工艺,在退浆工段就实现对PVA的生物降解,不仅能大大减少PVA废水的排放,还能避免化学退浆过程中高温和氧化造成的棉纤维损伤。研究微生物降解PVA的条件及PVA生物降解过程机制将有助于PVA降解高效菌的筛选和实现PVA降解酶在退浆工艺上的运用,对于减轻环境污染将具有重大的意义。本文详细研究了青霉菌株WSH02-21(Penicillium sp. WSH02-21)、委内瑞拉链霉菌GY1(Streptomyces venezuelae GY1)以及混合微生物体系(以下简称混合体系)降解PVA的条件,并用HPLC、高效凝胶过滤色谱法(HPGFC)、红外光谱(IR)和末端限制性酶切片段长度多态性方法(T-RFLP)等方法分析Penicillium sp.WSH02-21、Streptomyces venezuelae GY1、紫色杆菌WSH04-01(Janthinobacterium sp. WSH04-01)及其混合体系降解PVA1799的过程,研究不同微生物降解PVA的机制。主要研究结果如下:1、对菌株Penicillium sp. WSH02-21产PVA降解酶的营养条件进行了系统研究,发现该菌株在普通的霉菌培养基中不产PVA降解酶;以低浓度的可溶性淀粉为碳源、以酵母作为氮源时,该菌株可以产少量PVA降解酶;在以PVA为唯一碳源的培养基中,该菌产PVA降解酶酶活及单位质量细胞产酶水平有了明显的提高。以NH4Cl作为合成培养基的氮源,研究了20种氨基酸和部分维生素对青霉WSH02-21产PVA降解酶的影响。结果发现,苏氨酸是Penicillium sp. WSH02-21产生PVA降解酶的必需氨基酸,培养基中苏氨酸浓度必须高于12 mg/L该菌株才能产生PVA降解酶。2、分离得到一株产PVA降解酶的放线菌GY1,根据其16S rDNA全序列、生理生化特征以及细胞壁化学成分,确定该菌株属于Streptomyces venezuelae。这是关于放线菌产生PVA降解酶的首次报道。菌株Streptomyces venezuelae GY1产生的PVA降解酶是一种诱导酶。在PVA培养基中添加微量的葡萄糖有利于该菌株产PVA降解酶,但高浓度葡萄糖(>3 g/L)对PVA降解酶的合成有明显的抑制作用。菌株Streptomyces venezuelae GY1利用PVA1799和PVA1788这两种聚合度相同而醇解度不同的PVA作为底物产生更多还原

【Abstract】 Poly(vinyl alcohol) (PVA) is widely applied in the textile as a sizing agent. But the cotton fabrics treated by PVA must be desized to enhance their water absorbency. In conventional desizing method, the cotton fabrics are washed with hot water and sometimes oxidant such as NaBrO2, etc. is used to remove PVA. Thus, the wastewater from the textile plant contains abundant PVA and oxidant agents. If PVA-degrading enzymes were used in the desizing process, the PVA concentration in the wastewater could be decreased. At the same time, the damage of cotton fabrics by high temperature and chemicals could be avoided. The investigation of PVA microbial degradation conditions and the mechanism of the degradation process can be helpful for the screening of effective strains for PVA degrading, thus enhance application of PVA-degrading enzymes in the desizing process. It is very important to relieve environment pollution in the textile industry.In this study, the conditions for biodegradation of PVA by Penicillium sp. WSH02-21, Streptomyces venezuelae GY1 and a mixed culture were investigated, respectively. The processes and mechanism of PVA degradation by these strains were studied via high performance liquid chromatography (HPLC), high performance gel filtration chromatography (HPGFC), infrared spectrometer (IR) and terminal restriction fragment polymorphism (T-RFLP). The major results are summarized as follows:1) The nutritional conditions for the production of PVA-degrading enzyme by Penicillium sp. WSH02-21 were investigated and the results showed that the strain did not produce PVA-degrading enzyme in the normal fungal media. When 1 g/L of soluble starch was used as sole carbon source and yeast extract as nitrogen source, very small amount of PVA-degrading enzyme was produced by the strain. When PVA was used as the sole carbon source, however, PVA-degrading enzyme activity and the specific enzyme activity increased significantly. It indicated that the PVA-degrading enzyme produced by Penicillium sp. WSH02-21 was inducible.The effects of the 20 amino acids and some vitamins on the production of PVA-degrading enzyme by WSH02-21 were investigated in the synthetic medium using NH4Cl as the nitrogen source. The results showed that threonine is a necessary amino acid for PVA-degrading enzyme production by Penicillium sp. WSH02-21.更多还原