Abstract: Nowadays，people pay much attention to chitosan and its degradation product due to its excellent physical characteristic and biological activity. In this study，a high Chitosanase-producing bacterium Mitsuaria sp.K1 was isolated from the soil of Qingdao seacoast by primary screening of plate specula and shaking cultivation. The optimization of fermentation conditions was studied by Response Surface Methodology. The results showed that，under the optimal composition of medium (1.0%powder chitosan，0.5%KNO3，0.22%KH2PO4，0.1%Na2HPO4，0.15%KCl，0.05%MgSO4?7H2O) and the optimal cultural condition(25.2 ℃ incubating temperature，25.4 hours incubating time，initial pH6.5，3% inoculation amount，100 mL medium/500 mL flask，160 r/min)，the maximal chitosanase activity of Mitsuaria sp.K1 could reach 11.56 U/mL which was 5.32 times of primary strain. In addition，due to Mitsuaria sp.K1 with lower temperature and shorter fermentation time of chitosanase production，it has a good potential in industrial fermentation.

Key words: chitosanase, Mitsuaria sp.K1, fermentation condition, response surface methodology, optimization

摘要： 壳聚糖（chitosan）及其降解产物因具有优良的物理特性和生物活性而被广泛关注。通过平板透明圈初筛、摇瓶复筛方法，从青岛海岸土壤中分离筛选到1株产壳聚糖酶活性较高的细菌Mitsuaria sp.K1，并对其产酶发酵条件进行了单因素试验和响应面优化分析试验。结果表明：在最适培养基组成（1%粉末壳聚糖、0.5%硝酸钾、0.22%KH2PO4、0.1%Na2HPO4、0.15%KCl、0.05%MgSO4?7H2O）和最佳培养条件（培养温度25.2 ℃，培养时间25.4 h，起始pH值6.5，接种量3%，装液量100 mL/500 mL摇瓶，160 r/min）下，Mitsuaria sp.K1的发酵粗酶液最高酶活平均达11.56 U/mL，比优化前的2.17 U/mL提高了4.32倍。与前人研究结果相比，该菌发酵产酶温度降低了5～10 ℃，产酶周期缩短了23～47 h，因此具有工业发酵应用价值。

关键词: 壳聚糖酶, Mitsuaria sp.K1, 发酵条件, 响应面法, 优化