| The medium and condition of liquid fermentation for broad-spectrum antagonistic endophytic Bacillus amyloliquefaciens TB2 strain were studied by single factor experiments and orthogonal tests. The results showed that optimum medium formula was 1.0% corn starch, 1.0% soybean powder, 0.5% (NH4)2SO4, 0.1% MgSO4·7H2O, 0.03% FeSO4·7H2O, 0.02% K2HPO4·3H2O and 0.01% KH2PO4. The optimum fermentation conditions were as follows, the pH of production medium was adjusted to 7.5 before sterilization, the fermentation was carried out in 250 mL erlenmeyer flask with 50 mL production medium inoculated with 3% seed culture at 35℃, 200 r·min-1 for 22~26 h. Under the optimum conditions the fermentation cell density could reach 8.52×1010 cfu·mL-1.The exnomic ferment condition of TB2 strain were investigated by 180 L and 270 L fermentation vessel based on optimum conditions and ferment dynamic in the shake flask. The results showed that the pH of production medium was adjusted to 7.5 before sterilization, the seed was tansited into the fermentation vessel containing 45% fermentation medium with 3% inoculant, the pO2 was set as 30% culture at 30~33℃. Ferment dynamic in the fermentation vessel were studied by the pH value, reducing sugar content, cell concentration, amino nitrogen and spore forming rate changes in fermentation process. The better draw-off timing was 32 h. The fermentation cell density could reach 3.0~6.5×1010 cfu·mL-1, spore forming rate was more than 95%. Determination of inhibition activity of various concentrations of fermentation broth was carried to cucumber fungus wilt disease, banana anthracnose, tomato gray mold and tomato leaf mold. The results showed that fermentation broth was antagonized against the growth of four tested plant pathogens, and the inhibitory rate was 29.5%~45.2%.The downstream treatment processes of TB2 strain fermentation liquor were processed by the spray drying. Related to quality index of technical powder was determined. The results showed that the number of living bacterial cells could reach 1.20×1011 cfu·g-1, mixed other bacteria rate were less than or equal to 3%, drying loss was 4.5%~7%, pH value was 6.0~7.5, 80%~90% could through the 75μm test sieves, the living bacteria number was more than 90% after half a year stored at room temperature or 4℃.The technical powder of TB2 strain was formulated into 1:500, 1:1 000, 1:1 500 and 1:2 000 concentrations of gradients respectively, then was used to control diseases of bananas storage, pepper phytophthora blight of capsicum fruits and seedlings. The control results showed that the TB2 strain could inhibit banana anthracnose and collar rot during the storage period, pepper phytophthora blight. The 1:500 concentration in the treatment was remarkably better than others. The relative control effect of to banana collar rot and anthracnose was respectively 34.32%~62.42% and 66.32%~73.90%, to pepper phytophthora blight of capsicum fruits and seedlings were 61.51%~76.39% and 63.30%~86.60% seprataly. The tests showed that the disease rate was decreased and the disease occurrence was delayed by the endophytic bacteria. In addition, it had better growth-promoting effect on pepper seedlings. This work provided a basis for rational use and evaluating efficacy and safety.
|
PDF Full Text Request