2株海洋真菌對(duì)間苯二甲酸二甲酯和甲醛的降解特性研究
發(fā)布時(shí)間：2018-08-15 19:10
【摘要】：苯二甲酸酯(PAEs)作為塑料產(chǎn)品中的增塑劑已被發(fā)現(xiàn)具有內(nèi)分泌干擾毒性。隨著塑料工業(yè)的發(fā)展,這類物質(zhì)對(duì)海洋生態(tài)環(huán)境造成巨大的威脅。在之前的研究中,我們從近海紅樹林沉積物中富集分離到1株P(guān)AEs的降解真菌Fusarium sp.DMT-5-3,其對(duì)不同同分異構(gòu)體的鄰苯二甲酸二甲酯(DMPEs)的降解途徑有很大的差異,暗示其產(chǎn)生的DMPEs降解酯酶具有很高的底物選擇性。本論文以間苯二甲酸二甲酯(DMI)為底物,誘導(dǎo)Fusarium sp.DMT-5-3產(chǎn)酶,通過離子交換層析、分子篩凝膠層析等方法分離純化到一個(gè)DMI的降解酯酶蛋白。純化的DMI酯酶蛋白分子量約76kDa,是由兩個(gè)相同亞基組成的二聚體蛋白；酶蛋白在50℃表現(xiàn)出最大的酯酶活性,低于40℃時(shí)酶活較穩(wěn)定；酶的最適pH為8.0,在pH6.0-12.0之間較穩(wěn)定；Cr3+、Cu2+、Hg2+等金屬離子強(qiáng)烈抑制酯酶活性,而Mg2+、Ca2+、Sr2+等金屬離子能夠促進(jìn)酯酶活性；底物特異性分析表明該DMI酯酶能夠水解間位與對(duì)位的苯二甲酸二甲酯,而對(duì)于鄰位的二甲酯以及單甲酯的三種同分異構(gòu)體均無水解能力,體現(xiàn)了很高的底物選擇性。酶學(xué)性質(zhì)比較顯示該DMI酯酶與我們之前利用對(duì)苯二甲酸二甲酯(DMT)為底物獲得的DMT酯酶完全不同,表明海洋真菌Fusarium sp. DMT-5-3可以產(chǎn)生不同的酯酶參與到DMPEs不同同分異構(gòu)體的水解當(dāng)中。 甲醛(HCHO)作為消毒劑廣泛應(yīng)用于海洋水產(chǎn)養(yǎng)殖業(yè)中,其能與蛋白和核酸產(chǎn)生非特異性反應(yīng),因而對(duì)大多數(shù)海洋生物具有很強(qiáng)的毒性。本論文從從東太平洋深海沉積物中分離得到一株甲醛降解真菌DY-F2,通過分生孢子顯微觀察和18SrRNA基因序列分析結(jié)合,將其鑒定為Penicillium chrysogenum DY-F2。該菌株表現(xiàn)出高甲醛耐受力,能在甲醛濃度高達(dá)3000mg/L的條件下生長(zhǎng)。1000mg/1甲醛存在下,真菌Penicillium chrysogenum DY-F2的最適生長(zhǎng)溫度為25℃,最適生長(zhǎng)pH值是6.0。該菌株能以甲醛作為唯一碳源和能源,經(jīng)由中間代謝物甲酸完全降解甲醛。甲醛的真菌降解符合一級(jí)反應(yīng)動(dòng)力學(xué)模型。本研究表明,深海沉積物真菌具有海洋環(huán)境中甲醛污染生物修復(fù)的應(yīng)用潛力。
[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，
本文編號(hào)：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，
本文編號(hào)：2185141
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