根据酵母形态学特征、生理生化特性和ITS区序列的测定结果把产植酸酶酵母RCEF4907菌株分类鉴定为东方伊萨酵母Issatchenkia orientalis。利用亚硝基胍、紫外线、亚硝酸和氯化锂4种诱变剂对酵母RCEF4907菌株进行复合诱变处理,将经过处理的菌悬液用植酸钙琼脂平板进行初筛,然后取发酵上清液在37℃,pH2.5的条件下,利用钒钼酸铵比色法测定植酸酶活力进行复筛。经过多次诱变处理后,最终从大量的突变菌株中筛选出高产植酸酶的G3297突变株,其植酸酶活性达到409 U/mL,是出发菌株RCEF4907的5.76倍。

The phytase-producing yeast RCEF4907 were identified as Issatchenkia orientalis based on its sequence,the morphological and physiological characteristics.A large number of mutants were qualitatively screened by calcium phytate agar medium after I.orientalis RCEF4907 isolate was mutated with Nitrosoguanidine,Ultraviolet,Nitrous acid and Lithium chloride.The ratio of clear zones to colony diameter of the mutants was used to estimate extracellular phytase production.The high-yield phytase mutant was isolated by quantitative analysis of phytase activity of fermentation broth with Vanadium-Ammonium Molybdate colorimetric method at 37℃ and pH2.5.The phytase activity of the mutant G3297 obtained from a great amount of mutants was 409U/mL,which was 5.76 times than the I.orientalis RCEF4907.