产低温脂肪酶菌株Geotrichum candidum ch-3的选育、发酵条件及酶学性质研究

从新疆昌吉市油脂化工厂的含油冻土中筛选到一株产低温脂肪酶的菌株ch-3，形态鉴定及18SrDNA序列分析表明该菌株为白地霉，命名为Geotrichum candidum ch-3。我们对其生长及产酶情况和酶性质做了初步研究。该菌株的最适生长温度是20℃。玉米浆、豆油可显著促进脂肪酶的产生。粗酶液经双水相萃取和Sephadex G-75凝胶过滤分离纯化后进行酶学性质的研究。该脂肪酶最适作用温度为35℃，在0℃可保持66%的相对酶活性，最适pH值为7.0，对热较敏感，50℃处理20min，剩余酶活为55%，Fe2＋、Cu2＋、Mn2＋以及Ca2＋对酶有较强的激活作用。

Cold-adapted Lipase Produced by Geotrichum candidum ch-3: Screening, Fermentation Condition and Enzyme Characterization

A strain ch-3, which produces cold-adapted lipase, was isolated from the frozen soil containing oil of Changji lipidic chemical plant, Xinjiang province. The morphology identification and 18S rDNA sequence analysis showed that it was Geotrichum candidum spp. and named as Geotrichum candidum ch-3. The optimal growth temperature of strain ch-3 is 20℃. Corn serum and bean oil in medium enhances the secretion of lipase. The enzyme purification was performed by double water phases extraction and gel filtration with Sephadex G-75. The optimal temperature and pH for lipase activity are 35℃ and 7.0 respectively. At 0℃, the lipase still has 66% relative enzyme activity. The lipase shows high thermolability, remaining 55% activity after incubation at 50℃ for 30min. The enzyme activity was stimulated by Fe2＋、Cu2＋、Mn2＋.