Antagonistic Mechanism Of Strains A57, A178(Bacillus Spp) And Their Antagonistic Substanc, Control Effect And Growth Promoting

Identified the position of the A57 and A178 two strains,and studied antagonistic mechanism 0f antagonistic bacteria A57 and A178 against Rhizoctonia solani, Fusarium oxysporum f.sp.vasinfectum and Verticillium dahliae of cotton in this paper, Then, and studied the compounds ,physical and chemical character of antagonistic substance. At the same time, tested control effect of antagonistic filtrate of A57 and A178 against Rhizoctonia solani, Fusarium oxysporum f.sp.vasinfectum,and Verticillium dahliae. The results were as follows:1.identification of A57 and A178Established the position of the two strains based on the results of morphologic characteristics, physiological and biochemical properties and phylogenetic analysis of 16SrDNA sequence.eventually A57strain was identified as Brevibacillus brevs and A178 was identified as Bacillus subtilis.2. Antagonistic mechanism 0f antagonistic bacteria A57 and A178Bacteria A57 and A178showed stronger antagonism against Rhizoctonia solani ,Fusarium oxysporum f.sp.vasinfectum and Verticillium dahliaeon by plate duel culture. And the examination of antagonistic mechanism under light microscope showed that antagonistic substance of A57 and A178 appeared to inhibit pathogens by leading to mycelium rupture, distortion, abnormality, and inhibition bourgeon of conidiophore ,and leading to abnormality of conidiophore.3.Obstruction antagonistic substance of A57 and A178 and physical and chemical character of crude antagonistic proteinObtained antagonistic crude protein of A57 and A178 by (NH4)2SO4 precipitation. And tested the antagonistic activity against Fusarium oxysporum f.sp.vasinfectum, the results showed the best antagonistic activity by 70%(NH4)2SO4 precipitation, A57 and A178 Average inhibitory rate were 23.7%,22.3% respectively.Studied physical and chemical character of crude antagonistic protein. the results showed crude substance of A57 and A178 endured heat, and not to sensitive to chloroform, but the crude substance of the two strain were sensitive to Tryroteinase treatment. Their antagonistic activity adapted to pH5-pH7 , and have partly antagonistic activity on bitter acid (pH3) and alkali (pH9).5. control phytopathogenic and growth promoting of A57 and A178The cotton seed was treated by different dilution times of extract filtrate liquid treated and was planted in the nutrition soil ,and tested control rate against different phytopathogenic . The control rate with extract filtrate liquid of dilution 10 times of A57 and A178 were 56.8%,54.4% against Fusarium oxysporum f.sp.vasinfectum of cotton respectively. ,A178 showed stronger antagonism against Rhizoctonia solani,with control rate of 63.3%,Then the exudates filtrate liquid of antagonistic strain different dilution times was made different PDA plates, and put the asepsis seeding on it ,found that the extract filtrate liquid enhanced growth of seeding.,but extract filtrate of A57 with dilution 10 times caused radical intumescence ,abnormality .And extracted filtrate from seeding which was treated antagonistic extract filtrate and tested activity against Fusarium oxysporum f.sp.vasinfectum. Result showed inhibition rate of A57 and A178 were 5.7%,7.6% respectively.