嗜盐脂肪酶产生菌的筛选及其粗酶性质

从内蒙古锡林浩特地区盐湖菌种样品分离获得一株嗜盐脂肪酶高产菌, 结合生理生化试验和16S rDNA序列分析结果, 鉴定并命名为Haloterrigena thermotolerans Z4。该菌最适生长NaCl浓度为3.5 mol/L, 最高生长温度为60°C, 属于嗜盐耐热古生菌。粗酶性质研究表明, 金属离子(Ba2+、Fe2+、Cu2+)对酶有激活作用, 酶活不同程度的提高了20%~30%; 该酶受EDTA的抑制, 酶活下降了20%, 受PMSF的完全抑制。该酶对NaCl有较高的依赖专一性, 至少需要0.5 mol/L NaCl维持活性并且高浓度NaCl可以提高其耐热水平。醇类物质对于提高酶的热稳定性有一定作用, 丙三醇效果最好。该酶对短链底物对硝基苯酚丁酸酯(p-NPB)的最适水解条件为：pH 8.0、70°C、3.5 mol/L NaCl; 而对长链底物对硝基苯酚十六酸酯(p-NPP)的最适水解条件为：pH 8.0、80°C、2.5 mol/L NaCl。

Screening of a Halobacteria Strain Producing Halophilic Lipase and Characterization of Crude Enzyme

A halobacteria strain Z4 producing extracellular halophilic lipase screened from Hypersaline lakes of Inner Mongolia was identified as Haloterrigena thermotolerans. The crude lipase from Z4 was partially characterized using p-NPB. The activity of crude lipase was markedly increased 20%~30% by metal ions (Ba2+,Fe2+,Cu2+), but was obviously decreased 20% by EDTA. The lipase was completely inhibited by PMSF. The activity and heat resistance of enzyme was increased by NaCl, suggesting that the enzyme has strong dependence and specificity on NaCl. The thermostability of the crude enzyme was increased by alcohols, the glycerin is the best one. The optimum conditions for the crude lipase hydrolyzing p-NPB were followed: 3.5 mol/L NaCl, 70°C and pH 8.0, and the optimum conditions for the crude lipase hydrolyzing p-NPP were followed: 2.5 mol/L NaCl, 80°C and pH 8.0.