Analysis on the Antifungal Activity of Bacillus subtilis Strain Bs-916 and Its Extract

Bacillus subtilis strain Bs-916 which was isolated from rice field soil was used in controlling rice shealth blight and rice false smut.Bs-916 and its extract exhibited high antifungal (antibacterial) activity toward Rhizoctonia solani,Fusarium moniliforme,Fusarium oxysporum,Picularia grisea,Ustilaginoidea virens,Xanthomonas campestris pv.oryzae and Xanthomonas campestris pv.oryzicola.Inhibition rate of Bs-916 and its extract were 95.4％ and 70.7％ toward R.solani,100% and 100% toward U.virens,respectively.The extract of Bs-916 was deposited by acetone,PEG6000,ammonium sulfate and different pH value,the extract were also drawn by Ultra-4 centrifugal devices,and the above distilled substances showed high antifungal activity toward Rhizoctonia solani.The antifungal activity of the extract was decreased when it was treated with protease K.The results implied that an antifungal protein existed in the extract of Bs-916.