| 摘要: |
| 对一株分离自深海热液口的超嗜热古菌(Thermococcus sp. HJ21)菌株进行了α-淀粉酶发酵条件的优化和酶学性质的研究。该菌株发酵9 h 后到达产酶高峰, 产酶温度范围为60—90℃, 其最适产酶温度为80℃。产酶pH 范围为5.0—9.0, 最适产酶pH 为7.5。产酶NaCl 浓度范围为0.5%—4.0%, 2.5 %为最适宜NaCl 浓度。糖原、淀粉、麦芽糖、酵母膏和蛋白胨促进产酶。该菌株产生的α-淀粉酶的分子量为51.4 kDa, 酶的最适作用温度为95℃, 在100℃仍有60%的酶活力。酶在90℃的半衰期为5 h, 在100℃ 2 h 仍有40%的残余酶活, 酶的热稳定性不依赖Ca2+。酶的最适作用pH 为5.0, pH 4.5 仍有80%的酶活力, pH 在5.5—7.0 较稳定(80℃ 4 h)。金属离子1 mmol/L 的Mg2+、Co2+、Sr2+、Ba2+、K+、Na+对酶有激活作用, Cu2+、Pb2+、Hg2+、Zn2+、Al3+对该酶均有抑制作用。
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| 关键词: 超嗜热古菌, 热球菌属, α-淀粉酶, 产酶条件, 酶学性质 |
| DOI：10.11693/hyhz200901004004 |
| 分类号: |
| 基金项目:江苏省“六大人才高峰” 第三批资助项目：06-A-017 号, 江苏省教育厅自然科学基金项目：06KJB550004 号, 江苏省海洋生物技术重点建设实验室项目：2006HS008号, 连云港市自然科学基金项目：KK06076 号 |
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| Hyperthermophilic Archaeon, Thermococcus, α-Amylase, Production, Characterization |
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WANG Shu-Jun,LU Zhao-Xin,QIN Song,LU Ming-Sheng,LI Fu-Chao,LIU Hong-Fei,DENG Xiang-Yuan
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1.College of Food Science and Technology, Nanjing Agricultural University;2.Jiangsu key Laboratory of Marine Biotechnology, Huaihai Institute of Technology;3.Institute of Oceanology, Chinese Academy of Sciences
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| Abstract: |
| The production and characterization of α-amylase from Thermococcus sp. HJ21 are studied. The maximum enzyme production is achieved after 9 h cultivation. The ranges and the best points of α-amylase production are 60—90℃, 80℃; 5.0—9.0, 7.5 in pH; and 0.5%—4.0%, 2.5% for NaCl concentration, respectively. The result shows that adding yeast extract, peptone, glycogen, starch, and maltose could enhance the enzyme production, and the strain HJ21 could produce extracellular thermostable and acid-stable α-amylase. In addition, the molecular weight of the enzyme is estimated 51.4 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The maximal activity of α-amylase occurs at 95℃; the half-life of the enzyme is 5 h at 90℃; and over 40% of them remain active 2 h after incubation at 100℃. Meanwhile, no Ca2+ is required for thermostability. The enzyme remain stable in a wide pH range of 5.5 to 7.0 (at 80℃ 4 h), and best in 4.5—5.0. Moreover, the enzyme can be activated by Mg2＋, Co2+, Sr2＋, Ba2+, K＋, and Na+, and inhibited by Cu2＋, Pb2＋, Hg2＋, Zn2＋, and Al3+.
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| Key words: Hyperthermophilic Archaeon, Thermococcus, α-Amylase, Production, Characterization |
