中国生物工程杂志

Fungal diseases of plant reduce yield and productivity of many economical crops. Chemical control of disease is costly both to the environment and to human .Therefore, screening antifungal bacteria for use in biological control becomes more important. Bacillus amyloliquifaciens isolated from the compost showed strong antifungal activity against a lot of plant pathogens. By ammonium sulphate precipitation, the crude extract was obtained from the culture medium of Bacillus amyloliquifaciens. Then it was isolated and purified by gel filtration on Hiprep 26/10 Desalting column，ion-exchange chromatography on HiLoad 26/10 Q Sepharose column. There are four fractions after the two steps above, and the third one was collected to be analyzed by HPLC. Eventually, three peaks were obtained, the second one which showed strong antifungal activity was collected as a pure substance. The molecular weight of it is 1498 Da as determined by ESI mass spectrometry. The pure substance shows strong inhibitory activity against Fusarium oxysporum f. sp. spinaciae O-27, Fusarium graminearium，Ramularia tulasnei Sacc and Coniothyrium diplodiella. The abnormal hyphal growth of Ramularia tulasnei Sacc by the active substance such as twisted hypha, swollen tips was observed, In addition, the number of the conidia is less.