| Commelina communis L.is a kind of malignant weed which has strong adaptability and distribution in the world.It caused serious harm to China's agricultural production.In recent years,with the increasing concern to pesticide residues,food environmental safety and weed resistance,more and more attention has been paid to biological control.Phoma herbrum SYAU-06 strain is isolated from the susceptible Commelina communis,which is a pathogenic fungu that highly infects Commelina communis,causing its withering or even death.It and has the potential to develop as a biological herbicide.This test based on Phoma herbarum SYAU-06 strain as the research object to explore the production conditions of pycnidium of Phoma herbarum SYAU-06 strain.Also the liquid fermentation conditions were optimized by shaking flask test and the optimal fermentation process was determined.The strains were expanded cultured by 5 L and 20 L fermentors,and increased the biomass of strain by potimize the fermentation parameters of the fermentors.Develop the preparation research of Phoma herbarum,processing into Phoma herbarum SYAU-06 water emulsion(W/O)and Commelina communis on control experiment was carried out.The results of this paper provides a theoretical basis for the scale production of Phoma herbarum SYAU-06 strain.The conditions of pycnidium number induced by Phoma herbarum SYAU-06 were studied.The results showed that under the plate culture medium,the pycnidium number was the most in OMA+ dayflower juice culture medium,which was 45.67 /cm2.The optimum cultrue conditions were temperature 25-30 ?,L:D=12:12,p H range 7-8.In the solid fermentation matrix,the pycnidium number was the highest in the wheat bran with the ratio of material to water of 2:1,when the ratio of wheat and rice was 3:1,the the number of pycnidium did not increase significantly,and the time was shorten obviously.After induction of sporulation,the pycnidium number increased significantly compared with before,but it still can not meet the requirements of scale production,the mycelium was selected as the indexes for subsequent research.Using the single factor test method selected the best carbon source for fermentation culture medium selection of sucrose,concentration was 3%,the best nitrogen source was peptone with a concentration was 0.25%.Placktt-burman(PB)experimental design and response surface optimization method box-behnken(BBD)were used to optimize the liquid flask fermentation process of SYAU-06 strain.The results showed that temperature,rotationspeed,liquid loading amount and inoculation amount were the four factors that had significant influence on the liquid shake flask fermentation.A certain range of p H change on strain biomass had little impact.Under the conditions of temperature of 28.76?,rotation speed of139.86 r/min,liquid loading amount of 124.42 m L,inoculation amount of 4.96,and natural p H,the dry weight of mycelium in the liquid shake flask fermentation of Phoma herbarum was 15.41 g/L,which was close to the predicted value of the model.The parameters of 5 L fermentor were optimized.After primary fermentation,Phoma herbarum SYAU-06 strain was inoculated into 5 L fermentor for secondary fermentation to expand culture the strain.The results showed that the p H value of the regulated fermentation process was 6,the rotating speed was 200 r/min,the air volume was 4 L/min,the fermentation time was 6 d,and the biomass of the strain reached the highest level,which was 15.26g/L.The optimum parameters of 20 L fermentation medium test were rotating speed 250 r/min,air volume 0.4 m3/h and p H of 6.Under this condition,the biomass of fermentation strain was1.26 times higher than that of 5 L fermentor.By the biocompatibility test,the emulsifier with good compatibility with Phoma herbarum was Tween-80,thickener was CMC and defoamer was organo silicone.Finally determining the Phoma herbarum SYAU-06 water emulsion formula was: the Phoma herbarum 1.75×106 cfu/m L,emulsifier 5% Tween-80,thickener 5% CMC,defoamer 2%organo silicone.The self-emulsification method was used to make water-in-oil water emulsions,with the Phoma herbarum and Tween-80 as the oil phase and the rest as the water phase.The results of indoor pot test showed that when the concentration of Phoma herbarum water emulsion was 1.75 ×106 cfu/m L and the leaf age was 3-4 leaves,the control effect reached 51.36%.The field test results showed that the dosage of Phoma herbarum water emulsion was 1950 m L a.i./hm2,and the best fresh and heavy control effect was 50.78% after21 days of application. |
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