This study applies UV-lithium chloride mutagenesis to Streptomyces gilvosporeus,yielding three stable,high-yielding natamycin mutant strains.The results show that the optimal conditions for compound mutagenesis are lithium chloride mass content of 0.5%and ultraviolet irradiation time of 90 s,and the average yield of natamycin in the fermentation broth of the three mutant strains with high yield under these conditions is 3 977 mg/L,which is 32.5%higher than that of the original strain.After five consecutive passages,the genetic traits of the mutant strain are stable,and the yield of natamycin in the fermentation broth of the SG-14 mutant strain is the highest in the 300 L fermentation tank,reaching 4 176 mg/L,which is 35.9%higher than that of the original strain,and the cycle is shortened by 15 h.This breeding technology significantly improves the fermentation efficiency of production bacteria,and is of great value for industrial production and process improvement.
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