In order to explore the mutation breeding method of screening high-yield strains of β-carotene

the negative bacteria spores of Blakeslea trispora were irradiated by low-energy nitrogen ions. The effect of different implantation doses on the survival rate

mycelium growth

colony morphology

sporulation characteristics and mutation rate of Blakeslea trispora was investigated and the β-carotene content was detected by high-performance liquid chromatography. The results showed that with the increase of N+implantation dose

the survival rate showed the "saddle" dose-response curve. In addition to the dose of 14×1015N+/cm2

the flat mycelium density increased

the flat mycelium length decreased

the flat mycelium growth rate accelerated

the flat mycelium color became yellow and a certain amount of brown latent spores grew. The overall mutation rate and positive mutation rate showed the trends of increasing firstly and then decreasing.At the dose of 12× 1015N+/cm2

the total mutation rate and positive mutation rate reached maximum and a β-carotene high-yielding strain BT12-12-05 was selected and its β-carotene productivity reached 1.252g/L

which increased by 25% compared to that of initial strain of 1.044g/L. It was found that the mutant had a good genetic stability through passage experiment.