2株海洋真菌对间苯二甲酸二甲酯和甲醛的降解特性研究
发布时间：2018-08-15 19:10
【摘要】：苯二甲酸酯(PAEs)作为塑料产品中的增塑剂已被发现具有内分泌干扰毒性。随着塑料工业的发展,这类物质对海洋生态环境造成巨大的威胁。在之前的研究中,我们从近海红树林沉积物中富集分离到1株PAEs的降解真菌Fusarium sp.DMT-5-3,其对不同同分异构体的邻苯二甲酸二甲酯(DMPEs)的降解途径有很大的差异,暗示其产生的DMPEs降解酯酶具有很高的底物选择性。本论文以间苯二甲酸二甲酯(DMI)为底物,诱导Fusarium sp.DMT-5-3产酶,通过离子交换层析、分子筛凝胶层析等方法分离纯化到一个DMI的降解酯酶蛋白。纯化的DMI酯酶蛋白分子量约76kDa,是由两个相同亚基组成的二聚体蛋白；酶蛋白在50℃表现出最大的酯酶活性,低于40℃时酶活较稳定；酶的最适pH为8.0,在pH6.0-12.0之间较稳定；Cr3+、Cu2+、Hg2+等金属离子强烈抑制酯酶活性,而Mg2+、Ca2+、Sr2+等金属离子能够促进酯酶活性；底物特异性分析表明该DMI酯酶能够水解间位与对位的苯二甲酸二甲酯,而对于邻位的二甲酯以及单甲酯的三种同分异构体均无水解能力,体现了很高的底物选择性。酶学性质比较显示该DMI酯酶与我们之前利用对苯二甲酸二甲酯(DMT)为底物获得的DMT酯酶完全不同,表明海洋真菌Fusarium sp. DMT-5-3可以产生不同的酯酶参与到DMPEs不同同分异构体的水解当中。 甲醛(HCHO)作为消毒剂广泛应用于海洋水产养殖业中,其能与蛋白和核酸产生非特异性反应,因而对大多数海洋生物具有很强的毒性。本论文从从东太平洋深海沉积物中分离得到一株甲醛降解真菌DY-F2,通过分生孢子显微观察和18SrRNA基因序列分析结合,将其鉴定为Penicillium chrysogenum DY-F2。该菌株表现出高甲醛耐受力,能在甲醛浓度高达3000mg/L的条件下生长。1000mg/1甲醛存在下,真菌Penicillium chrysogenum DY-F2的最适生长温度为25℃,最适生长pH值是6.0。该菌株能以甲醛作为唯一碳源和能源,经由中间代谢物甲酸完全降解甲醛。甲醛的真菌降解符合一级反应动力学模型。本研究表明,深海沉积物真菌具有海洋环境中甲醛污染生物修复的应用潜力。
[Abstract]:Phthalate (PAEs) has been found to have endocrine disrupting toxicity as plasticizer in plastic products. With the development of plastic industry, these substances pose a great threat to marine ecological environment. In previous studies, a strain of PAEs degrading fungus Fusarium sp. DMT-5-3 was isolated from offshore mangrove sediments. The degradation pathways of dimethyl phthalate (DMPEs) from different isomers were very different. It is suggested that the DMPEs-degrading esterase produced by it has high substrate selectivity. In this paper, dimethyl isophthalate (DMI) was used as the substrate to induce the production of Fusarium sp.DMT-5-3, and a degradation esterase protein of DMI was isolated and purified by ion exchange chromatography and molecular sieve gel chromatography. The molecular weight of purified DMI esterase protein is about 76kDa. it is a dimer protein composed of two same subunits, the enzyme protein exhibits the largest esterase activity at 50 鈩，
本文编号：2185141
[Abstract]:Phthalate (PAEs) has been found to have endocrine disrupting toxicity as plasticizer in plastic products. With the development of plastic industry, these substances pose a great threat to marine ecological environment. In previous studies, a strain of PAEs degrading fungus Fusarium sp. DMT-5-3 was isolated from offshore mangrove sediments. The degradation pathways of dimethyl phthalate (DMPEs) from different isomers were very different. It is suggested that the DMPEs-degrading esterase produced by it has high substrate selectivity. In this paper, dimethyl isophthalate (DMI) was used as the substrate to induce the production of Fusarium sp.DMT-5-3, and a degradation esterase protein of DMI was isolated and purified by ion exchange chromatography and molecular sieve gel chromatography. The molecular weight of purified DMI esterase protein is about 76kDa. it is a dimer protein composed of two same subunits, the enzyme protein exhibits the largest esterase activity at 50 鈩，
本文编号：2185141
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