苏云金杆菌酪氨酸酶基因转化子黑色素的研究

Melanin Study of the Transformant of Bacillus thuringiensis Containing Tyrosinase Gene

苏云金杆菌(Bacillusthuringiensis,Bt)是使用广泛的杀虫细菌。将构建的含有嗜麦芽假单胞菌酪氨酸酶基因的重组质粒导入苏云金杆菌体内,使后者获得了稳定产生黑色素的能力。所产黑色素是无定形物质,在大多数有机和无机溶剂中溶解度低或不溶解,在碱性溶液中有较好的溶解性,在中性及弱酸性溶液中溶解度低,pH<4时沉淀;可用过氧化氢或次氯酸钠氧化,也能被银离子或硫化氢还原;含有天然物质中少见的自由基,并能清除由紫外线诱导产生的自由基;能吸收所有波长的光线,在紫外波长下吸收值最大,能有效地保护紫外辐射对蛋白质及DNA等生物大分子物质的损害,具有很强的抗辐射作用。使转化子抗辐射能力显著增强,杀虫活性稳定保持;能抵抗病毒的侵袭,生长旺盛;对畜禽安全。

Bacillus thuringiensis is a widely used insect-killing bacterium. Tyrosinase gene of Pseudomonas maltophilia AT18 has introduced into B. thuringiensis with recombinant plasmid to enable it the ability to produce melanin steadily. The melanin is a kind of nonfixiform material. In most of organic and inorganic solvent it has low solubility or is insoluble. In alkaline solution it has fairly good solubility, but low in neutral or weak acid solution. It deposits when pH〈 4. It can be oxidized by H2O2 or NaClO. Ag^＋ or H2S can also reduce it. It has free radical rarely existed in natural matter, it can eliminate free radical generated by UV ray. It can absorb ray of all sorts of wavelength. It effectively protects protein, DNA and other biomacromolecule matter against the damages by UV ray.Antiradiation effect of melanin is quite strong. The results of assay showed that antiradiation effect of the transformant is quite strong. These keep its insect-killing activity remain stable, can resist the viral attack, vigorous growth,and safe to livestock and fowl.