On the basis of screening of Paecilomyces tenuipes,Paecilomyces fumosoroseus,Paecilomyces farinosus,Pleurotus ostreatus,Lentinus edodes and Flammulina velutipes,this paper chooses Paecilomyces fumosoroseus as original strain of UV treatment.The cholesterol oxidase producing mutant strain MFEC006 was obtained from Paecilomyces fumosoroseus,the enzyme activity reached 0.548 3 U/mL,154% higher than that of the starting strain.The properties of the mutant strain were stable after eight generations.The optimal f...