Cordyceps militaris is a valuable medicinal and edible fungus with high medical and economic value . The effects on the preparation conditions of protoplast from Cordyceps militaris , including enzymes , temperature and time of enzymolysis , stabilizing agent of osmotic pressure and the mycelium age of Cordyceps militaris were investigated by single-factor and the orthogonal design . Protoplast from Cordyceps militaris was mutagenized with UV . The experiments results showed that the highest yield of protoplast could be obtained by using 1％ lywallzyme +0 .5％ snailase +0 .5％ cellulose as cell wall digesting enzyme , mannitol as stabilizer of osmotic pressure , mycelium of 4 days and enzyme treatment for 2 hours at 30℃. The production of protoplast reached 9 .2×106 /mL . Then mutant 44 #: was screened from 150 mutants with high exopolysaccharide yield and biomass . The biomass increased by lO％ and exopolysaccharide yield increased by 84 .3％ compared with those of the original strain . After lO generations , it still showed hereditary stability .The biomass and exopolysaccharide yield of the mutant 44 #: kept constantly .%蛹虫草是重要的药食兼用两用真菌,具有较高的医用及经济价值.本文通过单因素和正交试验的方法研究了不同酶系统、酶解温度、酶解时间、渗透压稳定剂、菌龄对蛹虫草原生质体形成的影响,并对蛹虫草原生质体进行紫外诱变,以生物量和胞外多糖产量为指标选育胞外多糖高产菌株.结果表明:在30℃、1%溶壁酶+0.5%蜗牛酶+0.5%纤维素酶条件下,以甘露醇为渗透压稳定剂对4日龄蛹虫草菌丝酶解2h,原生质体产量可达到9.2×106个/mL.从150株诱变株中筛选出1株最佳正诱变株,编号为44#,经深层培养其生物量比出发菌株提高10%,胞外多糖产量提高84.3%,继代培养10代后,遗传稳定性良好.
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