Abstract: An excellent strain of Rhizopus with high HE value and saccharification power from sweet rice starter was screened through flat plate primary screening and mutagenized by UV radiation. An excellent mutant strain with an HE value of 1.76 and a saccharification power of 1281 mg/(h ·g) was obtained, which were increased by 5.4% and 59.5% compared to those of the original strain, respectively. The optimal culture conditions for the mutant strain were culture temperature of 30 ℃, culture time of 3 days and corn flour concentration of 8 g/100 mL. Under the optimal conditions, the saccharification power of the screened strain was up to 1317 mg/(h ·g).

Key words: sweet rice starter, Rhizopus, UV-induced mutagenesis, saccharification power