Abstract：The high-yield strains produced a water-soluble fungicide for the control of postharvest pathogenic Penicillium of citrus was selected using the wild strain of Streptomyces lavendulae X33 as the starting strain and Penicillium digitatum as the indicator. A high-yield mutant strain S. lavendulae BP39 with genetic stability was obtained by three rounds of mutagenic treatment of ultraviolet, nitrosoguanidine, 5-bromouracil, and diaminopurine after natural screening. Its relative potency increased by 279% compared with the starting strain S. lavendulae X33. The results indicated that the methods employed by traditional physical and chemical mutagenesis could greatly improve the yield of secondary metabolites by wild strains, and it was a simple and rapid breeding way.
