Study on Antagonistic Mechanisms and Biocontrol Effect of Strain Bai-g1 Against Fusarium Wilt in Banana
|School||Guangdong Ocean University|
|Keywords||Banana Wilt Disease Antagonistic bacteria Antagonistic mechanism Control effect|
Fusarium wilt (Fusarium oxysporum f.sp. cubense race 4) In this paper, banana target organisms isolated from soil , filtering into one pair of Fusarium strains has better antagonism - White g1 the dialogue g1 strains identification, fermentation condition optimization , the antagonistic mechanism as well as potted prevention effect measurement aspects of research . Based on colony morphology , Determination of physiological and biochemical characteristics of the bacterial 16S rDNA molecular identification results , preliminary identification of antagonistic bacteria white g1 Paenibacillus genus ( of Paenibacillus sp ) . By a single factor and orthogonal test means complete white g1 determination of optimum fermentation conditions produce antibacterial substances . The test results showed that the optimum fermentation conditions for the inoculum size 2% , beef extract 0.4% , 0.25% glucose , sodium nitrate 0.25% , pH 7.0, temperature 28 ° C , shaking 150rpm , fermentation time 72h . Strains the white g1 (Paenibacillus sp) with sterile fermentation broth of Fusarium mycelium and conidia good inhibition. Banana wilt mycelial digestion , breaking local prominent deformity end enlargement , the protoplasm outflow ; conidia Plasmolysis , the protoplasm concentrated , lower germination rate . The plate method determination of the sterile fermentation filtrate antibacterial activity , inhibition zone of 21.3mm , 10 times the sterile fermentation filtrate dilutions inhibition of spore germination rate was 94.4 % . Antagonistic Strains white g1 antibacterial substances has good stability to temperature , acids, alkalis , sterile filtrate was sterilized at 121 ℃ for 10min inhibition zone can be maintained at 15.0mm pH2 to pH9 when , have better stability , 55 days storage zone of inhibition of 19.1mm. 60% saturated ammonium sulfate solution and the precipitation method can be effectively extracted to the antibacterial substances . The white g1 (Paenibacillus sp) The antibacterial activity of material is a proteinaceous material , the antimicrobial crude extracts from the antagonistic effect of the protein molecular weight of about 29.0KD, 33.5KD two kinds three enzymes , proteinase K, pepsin , trypsin , etc. very sensitive. Pot experiment was injured roots inoculated with 8 treatment , the results showed that: antagonistic bacteria the white g1 bacterial suspension concentration of 2.0 × 10 ~ 6 cfu / ml, 81.5% of the banana wilt biocontrol effect of banana seedlings . The white g1 against Fusarium can reach to reduce illness and improve plant resistance to disease , and to promote the role of banana seedling growth , showed a good prospect .