Abstract: Pectinase is widely applied to clarify fruit juice in food industry. Discover and excavate high quality pectinase suitable for industrial application can provide more choices for food industry. A new gene Bspg28b was cloned from Bispora sp. MEY-1, and efficient heterologous expression in Pichia pastoris GS115 was realized. After purification, the enzymatic property of recombinant enzyme was measured. Its optimum pH was 3.5 and optimum temperature was 65℃. The pH stability in acidity and neutral environment was very good, which could completely satisfy the need of fruit juice clarification process. BsPG28b was highly stable at 55℃, and still remained around 50% residual activity at 65℃ after 10 min. It was a scarce high quality pectinase with high temperature resistance from fungus resource. Evaluation on BsPG28a application efficiency discovered that it could remarkably improve the clarity of grape juice, thus had great potential for application in food industry.

Key words: polygalacturonase, Bispora sp.MEY-1, Pichia pastoris GS115, grape juice clarification

摘要： 果胶酶作为添加剂广泛应用于食品行业的果汁澄清工艺中，发现和挖掘适用于工业应用的优质果胶酶，能够为工业应用提供更多的选择。从嗜酸的Bispora sp. MEY-1基因组中克隆得到一个多聚半乳糖醛酸酶基因Bspg28b，并在毕赤酵母GS115中实现高效异源表达。对重组蛋白纯化后进行酶学性质的测定，其最适pH 3.5，最适温度为65℃，在酸性至中性的环境中具有很好的pH稳定性，完全满足果汁澄清工艺的需求；BsPG28b在55℃下保持高度稳定，在65℃中保温10 min后仍能剩余50%的酶活，是真菌来源中少见的耐高温优质果胶酶。对BsPG28b的应用效果进行评估发现，可显著提高葡萄汁的澄清度，体现巨大的应用潜力。

关键词: 多聚半乳糖醛酸酶, Bispora sp. MEY-1, 毕赤酵母, 葡萄汁澄清