Isolation And Characteristics Of Antagonistic Substance Produced By A Strain Of Bacillus Pumilus

This article elaborated a systematic research on one poplar canker disease antagonistic bacteria-Bacillus pumilus strain JK-SX001 which has been preserved in our lab.The study mainly focused on the non-protein antagonistic substance produced by Bacillus pumilus Strain JK-SX001 isolated from the zymotic fluid, also researched the mechanisms of restraining three pathogenic fungi species:Cytospora chrysosperma, Phomopsis sp. and Fusicoccum aesculi. Its physico-chemical properties were studied too.The non-protein antagonistic component JK-SX001-3# was isolated and purified,we also analyzed its elementary composition and chemical constitution..All these studies will provide a scientific foundation for the biological prevention against poplar canker disease.The mainly results were as follows:The results of prevention and treatment experiments in the room showed that zymotic fluid of the Bacillus pumilus strain JK-SX001 could intensely resist the three pathogenic fungi species Cytospora chrysosperma, Phomopsis sp. and Fusicoccum aesculi which crose poplar canker disease,the control efficiency of prevention and treatment experiments could reach the max 57.1%, and the therapeutic effect could reach the max 30.5%.The field experiments showed that:irrigated the root of every plant with 25mL zymotic fluid and smeared the poplar stem could reach better effect on the control of poplar canker disease.The mortality rate and disease index were lowest.The three treatments(smear the stem and irrigate every root with 75mL zymotic fluid,infiltrate the root,irrigate every root with 25mL zymotic fluid)all could thicken the saplings predominantly.But infiltrating the root could reach the best promoting effect. Compared with the control, the sapling height and diameter at breast height were increased by 9.4% and 25.2% respectly.The mechanism of the non-protein antagonistic substance from Bacillus pumilus strain JK-SX001 was studied by Oxford cup method and germinated-spores. At the same time, in order to determine the physical and chemical characteristics of the non-protein antagonistic substance, three pathogenic fungi species were used as instruction fungi. We studied the effect of light, temperature, pH, ultraviolet light and metalions on the stability of non-protein antagonistic substance. Validity of non-protein antagonistic substance was measured at room temperature. These results showed that the non-protein antagonistic substance had a strong inhibition to the mycelia growth and spore germination, and also could dissolve the spore. Light, temperature, UV irradiation had little effect on the antagonistic substance, while the pH value and metalions had a more significant effect on the activity of antagonistic substance.Three pathogenic fungi species Cytospora chrysosperma, Phomopsis sp. and Fusicoccum aesculi which could introduce poplar canker disease were restrained by Bacillus pumilus JK-SX001. It was isolated by Organic solvent toluene and purified by High performance liquid chromatography (HPLC) from the fermented culture, which was preliminarily identified to be dioctyl phthalate (DOP) based on searching Wiley Registry of Mass Spectral Data and infrared spectral analysis.The results of toxicity test showed that this substance had no harm to the branches and blades of poplar sapling.