产纤溶酶菌株根霉12^#的诱变育种及固态发酵培养基的优化

Breeding and Optimization of Solid State Culture Medium of Rhizopus Chinensis 12# for Fibrinolytic Enzyme Production

以产纤溶酶的菌株根霉 12 # 为出发菌株 ,对其进行紫外线 氯化锂复合诱变 ,筛选到74株制霉素抗性突变株。所有抗性突变株经进一步固态发酵筛选 ,获得了 4株稳定高产纤溶酶的正突变株 ,其纤溶酶产量分别比出发菌株提高 3 2 9%、2 1 5 %、2 2 3 %和 18 0 %。以其中的 1株为菌种 ,研究了固态发酵产生纤溶酶的培养基组成。采用单因素试验、均匀设计方法对固态发酵培养基的碳源、氮源、碳氮比、初始pH、加水量、无机盐加量进行了优化。结果表明 ,实验范围内根霉 12 # 固态发酵产生纤溶酶的适宜培养基组成为 :m (麸皮 )∶m (豆粕 )=1∶2 ,初始 pH5 0 ,加水量 0 75mL/g物料 ,MnSO4·H2 O和 (NH4) 2 SO4加量分别为 0 2 5 %和1 42 % (对物料 )。优化条件下的固态发酵纤溶酶产量平均达 744 5 7U/g物料。

A Rhizopus chinesis producing a fibrinolytic enzyme was mutagenized with UV combining LiCl and 74 nystatin resistant mutants were obtained All mutants were futher screened through repeated solid substrate fermentations and then 4 plus mutants with highly genetic stability were acquired The productivity of the fibrinolytic enzyme of plus mutants increased by 32 9%, 21 5%, 22 3% and 18 0% respectively compared with that of original strain The optimization of solid state fermentation medium of a plus-mutant for fibrinolytic enzyme production was studied The effects of proportion of wheat bran and soybean residues, initial pH and moisture level of culture medium, inorganic salts on the fibrinolytic enzyme productivity were investigated, and the levels of all ingredient of medium were determined by single factor and uniform design experiments The results showed that the optimum ratio of wheat bran and bean residues was 1∶2, and other components of culture medium were water 0 75*#mL, 0 0025*#g MnSO 4·H 2O and0 014*#g (NH 4) 2SO 4 per gram medium(dry weight) Under optimum conditions, yield of fibrindytic enzyme produced by Rhizopws Chinensis reached 744.57*#u/g.