植酸酶高产菌株的选育

Screening of phytase-producing strain

从土壤中分离到1株植酸酶高产菌株Pe0,初步鉴定为米曲霉.为了提高植酸酶活力,对Pe0菌株分别进行紫外线和亚硝基胍诱变处理,经初筛、复筛、遗传稳定性能检测,得到1株酶活相对较高、性状相对稳定的菌株Pe2#,酶活稳定在10.66U/mL,较原始菌株提高到3.34倍.另对其发酵条件进行优化,确定最适接种量为4%,最适pH为5.5,最适培养时间为6.5d.在此基础上进行培养基正交优化,结果表明:葡萄糖质量浓度为25g/L,蛋白胨质量浓度为4g/L,(NH4)2SO4质量浓度为2g/L,MgSO4.7H2O质量浓度为0.1g/L时所得菌株产酶活力最高.

In order to get the mutant strain which was stable and high production of phytase, the original Aspergillus oryzae strain Pe0 isolated in our laboratory was the staring strains, which were mutagenized separately by UV and nitrosoguanidine. By preliminary screening, rescreening and the detection of genetic stability, Pe2 was obtained which had a relatively high activity and stable characteristics. Its stable activity was 10. 66 U/mL, which increased 3.34 times comparing with original strain. To determine the optimum conditions for its enzyme productions, the fermentation conditions were optimized. The composition of the optimum medium were 25 g/L glucose, 4 g/L peptone,2 g/L （NH4）2SO4 and 0. 1 g/L MgSO4 ·7H2O.