Screening Of Strains Of Fusarium Graminearum Against Vomiting Toxin And Study On Its Supernatant Characteristics

[Objective] Fusarium graminearum is the main pathogen causing wheat scab,and it is also a major harmful microorganism in grain storage and food production.Diseases caused by the rapid growth of Fusarium graminearum not only reduce food production,but also produce toxins such as deoxynenol(DON)and zearalenone(ZEN),which pose a serious health hazard to animals.Inhibiting the growth and reproduction of Fusarium is the basic prerequisite for reducing the formation of head blight and toxins in wheat.The use of biological antagonism to control wheat scab is important for improving feed production quality and animal safety[Methods] Test I: Two strains of Fusarium graminearum strains were screened out from the strains kept in the laboratory.After antibacterial test,the antibacterial effect of B10 strain was the most ideal.Then the physiological and biochemical indexes of B10 strains were measured and morphology.Observation and 16 S rDNA binding to gyrB gene sequence analysis identified the strain B10 initially as Bacillus amyloliquefaciens in the genus Bacillus.Test 2: orthogonal analysis of the fermentation medium,fermentation temperature,fermentation time,initial pH of the culture medium,rotation speed of the shaker,and four factors of fermentation time,shaking speed,fermentation temperature,and initial pH of the medium According to the test,the best combination of antibacterial substance produced by strain B10 was fermenting time 72 h,fermentation temperature 37°C,shaking speed 200r/min,and initial pH of medium 8.0.Test 3: Through the fermentation liquor’s resistance to heat and pH tolerance experiments,the fermentation material in the fermentation broth has high stability to high temperature,and the antibacterial activity is not affected under alkaline conditions,nor is it obvious to the protease treatment.This feature is particularly similar to lipopeptides.Test 4: Observing the changes in the expression levels of related genes,it was found that the expression levels of Tri3,Tri4,Tri5,and Tri6 all showed a significant downward trend,limiting the further production of pathogenic bacteria.The expression level of Toxin-associated Tri101 gene in the 200μL and 400μL treatment groups showed an upward trend,but then decreased.By consulting the literature,Tri6 and Tri10 were transcription factors that could regulate the function of Tri101.[Conclusion] A strain which can inhibit the growth of Fusarium graminearum was identified and identified as Bacillus amyloliquefaciens.The optimum fermentation conditions of the antibacterial substance produced by the supernatant were determined,and the antibacterial substance was initially determined to be lipopeptides.The supernatant of the strain could inhibit the expression of DON-related genes in F.graminearum.