Abstract:Since Aspergillus oryzae（A.oryzae）are nonsusceptible to multiple antibiotics such as hygromycin，it is difficult to genetic modification on them.A.oryzae 3.042 was used as the parent strain to establish pyrG selection genetic modification system.Firstly，A.oryzae pyrG gene was destroyed through ultraviolet mutagenesis and homologous recombination method.Stable uridine/uracil auxotrophic mutants A.oryzae O11 and A.oryzae g-1 were obtained on medium containing uridine/uracil and 5-fluoroorotic acid.Then the mutants were used to transform the plasmid containing pyrG selectable marker，so as to obtain prototrophic complemented strains.The results showed that the mutant A.oryzae g-1 obtained from homologous recombination could successfully recover to be prototrophic，while the mutant A.oryzae O11 obtained from mutagenesis didn′t recover to prototrophic strains.This study demonstrated that uridine/uracil auxotrophic strains harvested from pyrG disruption in A.oryzae 3.042 could be directly used to genetically modify with its own pyrG gene as selectable markers.