Antimicrobial spectrum and stability of the fermentation broth of Streptomyces

Actinomycete mycelia were isolated from soil and a cylinder-plate assay was used to determine thatfermentation broth from these fungal mycelia had varying degrees of inhibitory activity towards 14 plant pathogenicfungal species and 2 plant pathogenic bacterial species. Among these, activity against Phytophthora parasitica var.nicotianae and Sclerotinia sclerotiorum was the highest, with inhibition diameters of 56.4 and 56.3 mm, respectively.A necrotic spot method was used to determine that the fermentation broth inactivated TMV. When inoculating 10 minafter mixing fermentation broth with viral sap, necrotic spot formation was inhibited 93.88%. Treatment 24 h beforeor after inoculation provided 87.93 and 42.21% inhibition, respectively, of necrotic spot formation. Preliminarystudies were conducted on stability of the fermentation broth. The antimicrobial substance in the fermentation brothwas stable to temperature, light, and pH.