Abstract:In order to improve the ability of Rhodococcus ruber to produce red pigment，an original strain Rhodococcus ruber YM-2 preserved by our laboratory was used to be screened with plasma mutation，plasmaplasma continuous mutation，ultraviolet mutation，ultraviolet-plasma compound mutation.Under the condition of plasma-plasma continuous treatment at 45，30 s，a genetically stable mutant A2was screened by screening plate and flask fermentation culture.The red pigment yield of A2was 1.12 g/L，increased by 30.32%compared with that of the original strain YM-2.In addition，comparing the effect of plasma，ultraviolet and ultravioletplasma treatments on positive mutation rate，the positive mutation rate of plasma-plasma continuous mutation wasthehighest39.40%，plasma-plasma continuous mutation could be used as a highly effective mutation method.