球孢白僵菌两种胞外几丁质酶的诱导和纯化

INDUCTION AND PURIFICATION OF TWO EXTRACELLULAR CHITINASES FROM BEAUVERIA BASS1ANA

球孢白僵菌突变株CH-1316在完全培养基中培养至对数前期后转入以胶体几丁质为唯一碳、氮源的液体诱导培养基中继续培养20～25h,几丁质酶被诱导产生;在对数生长期胞外几丁质酶活力最高。发酵液经(NH_4)_2SO_4沉淀、DEAE-纤维素层析和凝胶过滤分离出二种几丁质酶组分,在聚丙烯酰胺凝胶电泳图上显示出两条均一的带,并且每条带都具有几丁质酶活力。几丁质酶1既是外切酶又是内切酶,而几丁质酶2只表现内切酶活力。分子排阻法测得这两种酶的分子量分别为52000和39000。

Chitinases were induced when Beauveria bassiana CH-1316,a UV mutagenic mutant strain, was first grown in a complete medium to pre-logarithmic growth phase and then transferred to a medium containing colloidal chitin as a sole carbon and nitrogen source. Culture filtrates were collected about 20-25h after transferring, and this just occurred at the logarithmic growth phase and the peak time of chitinase activities. Two extracellular chitinases were purified to homogeneous by (NH4)2SO4 precipitation, DEAE-cellulose chromatography and gel filtration. Chitinase 1 showed mixed activities of endo-and exo-chitinase,while chitinase 2 was an endo-chitinase. The molecular weight of two chitinases were determined to be 52 000 and 39 000 by gel filtration.