产碱性纤维素酶菌株的选育和酶合成基本特性

芽孢杆菌x－6菌株经甲基磺酸乙酯（EMS）和紫外线（UV）复会诱变，从其万古霉素（Vm）抗性突变体中选育获得一突变株EV23，所产生的碱性核甲基纤维素酶（CMCase）酶活力由原来的0．84u／ml提高到3.53u／ml。EV23菌株所产该酶基本为组成性地合成纤维素酶，酶合成明显表现出抗降解物阻遏的特点，以葡萄糖为碳源培养，4％浓度时酶合成水平最高。酶合成效率受菌体生长速率影响较大。在高浓度易代谢基质和三羧酸循环中间物存在下，酶合成将受到一定程度的阻遏。酶合成还与能量代谢有关，探讨了外源ATP、cAMP对

SCREENING OF STRAIN PRODUCING ALKALINE CELLULASE AND STUDES ON THE CHARACTERISTICS OF THE ENZYME SYNTHESIS

After combination treatment of Bacillus sp. x-6 with EMS and UV, a mutant EV23 was obtained from its vancomycine-resistant mutants. The alkaline cellulase activity was improved from 0.84u / ml to 3.53u / ml. The synthesis of alkaline GMCase by EV23 occurred almost conshtutively with distinct resistance to catabolite repression. When glucose was used as carbon source, the enzyme produchvity reached the highest at the concentration of 4%. IN addition, the enzyme synthesis that was related to the cell growth rate colsely proceeded synchronously with the bacterial growth. The presence of glucose and intermediated in TCA at higher levels caused repression of GMCase formation to some extent. The effects of exogenous ATP and cAMP on the enzyme production were also investigated.