Dissertation > Agricultural Sciences > Plant Protection > A variety of control methods > Biological control

Study on Antagonistic Mechanisms and Biocontrol Effect of Strain Bai-g1 Against Fusarium Wilt in Banana

Author LiuXia
Tutor YuLi
School Guangdong Ocean University
Course Plant Pathology
Keywords Banana Wilt Disease Antagonistic bacteria Antagonistic mechanism Control effect
CLC S476
Type Master's thesis
Year 2010
Downloads 126
Quotes 2
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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 .

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