产壳聚糖酶菌株的分离、鉴定及发酵条件优化

Isolation,identification and production of a Mortierella sp. strain with chitosanase activity

从废弃食用菌培养基周围土壤中分离得到一株产壳聚糖酶的菌株,结合形态学特征与26SrDNA序列进行了分类学鉴定,结果表明,该菌株与高山被孢霉(Mortierella alpina)的同源性较高,达99%,初步鉴定为被孢霉属的一种,命名为KB-1001。并对该菌株的产酶特性进行了研究,结果表明,该菌株液体发酵培养产酶高峰出现在第84h,最适碳源为1%的水溶性壳聚糖,最适氮源为1.87%的(NH4)2SO4,摇瓶培养的最适初始pH值为6.0,最适温度为28℃～30℃,接种量为4%,最佳装瓶量为70 mL/250 mL,150 r/min摇瓶培养,经优化培养后,该菌株发酵液中壳聚糖酶活力最高达到8.130 U/mL。比原始的未经发酵条件优化的产酶活性提高了12.78%。

A chitosanase-producing fungus was isolated from soils and identified as Mortierella sp.KB-1001 based on the morphological observation and 26S rDNA gene sequence.The KB-1001 shares the highest similarity with Mortierella alpina which is 99%.By the single factor and orthogonal experiment,the optimal condition for the production by the strain was as follows（%）： chitosan 1.50,yeast extract 0.30,（NH4）2SO41.87,K2HPO4 3H2O 0.14,KH2PO4 0.03,NaCl 0.50,MgSO4 7H2O 0.13,glucose 0.1,the initial pH value 6.0.The optimal culture conditions for chitosanase production were as follows： 250 mL flask containing 60 mL medium,inoculum amount 4%,culture temperature 28℃,shaking cultivation at 150 r/min for 84 hours.Under the optimal cultivation conditions,the chitosanase activity of the broth could reach 8.130 U/mL.After optimization,the chitosanase activity of the broth could be increased by 12.78%.