Investigation on antimicrobial compounds from fermentation broth of Streptomyces flavofuscus G1, an endophyte isolated from Euonymus japonicas

Two antimicrobial compounds, G13 and G19, were isolated from fermentation broth of actinomycete Streptomyces flavofuscus G1, an endophyte isolated from Euonymus japonicas. The structures of G13 and G19 were identified as phencomycin(G13)and 4'-deacetyl-(-)-griseusin A(G19), respectively, based on the 1H NMR and 13C NMR and ESI-MS data, as well as the published literatures. G19 showed strong antibacterial activity against Xanthomonas oryzae pv. oryzae,Pseudomonas aeruginosa,Bacillus cereus and Staphylococcus aureuse, with minimum inhibitory concentration (MIC) value of 1.56 μg/mL. In addition, G19 could also effectively inhibit the mycelial growth of plant pathogenic fungi Valsa mali and Fusarium graminearum, and the IC50 values were 14.70 and 24.35 μg/mL, respectively. G13 exhibited strong antifungal activity against the mycelial growth of Sclerotinia sclerotiorum and V. mali, with IC50 values of 5.21 and 4.82 μg/mL, respectively.