Isolation and identification of antimicrobial components from broth of strain NYS-4

An actinomycete strain NYS-4 was isolated from a soil sample collected from the Qinling mountain of Shaanxi province of China.Antimicrobial activities of the fermentation broth of strain NYS-4 were investigated by methods of cylinder plate and inhibition of mycelial growth rate.The result of bioassay indicated that the broth of NYS-4 exhibited strong antimicrobial activities against several pathogens,such as Erwinia carotovora var., Kiwi ulcer disease germs,Bacillus subtilis,Fusarium oxysporum f.sp. Niveum,Alternaria alternate and Sclerotinia sclerotiorum .Purified by anion-exchange resin,gel column chromatography,ion-pair reversed-phase and HPLC-ESI-MS/MS,fourteen streptothticins including four new compounds, N -acetyl streptothticin A, N -acetyl streptothticin B, N -acetyl streptothticin B acid and streptothticin B acid,were isolated and identified from the metabolites of strain NYS-4 by bioassay-guided fractionation.