Screening Of Fusarium Graminearum Antagonistic Bacteria And Antibacterial Properties

Fusarium graminearum is the main pathogen of wheat scab, and is also a common harmful mold in cereal grain storage as well as food production process. Crop diseases caused by this pathogen in field will not only reduce the grain production, but also polluted the cereal toxins of DON and ZEN, which does serious harm to human and animal health.To inhibit the growth and reproduction of Fusarium graminearum is an important premise which reduce the incidence of wheat scab and toxin formation. It is of most significance to increase cereal production and improve food quality by biological antagonism prevention and treatment of wheat scab and toxin formation. In this study, we isolated antagonistic strain of Fusarium graminearum from wheat scab field soil, classified and identified the antagonistic strain, then separateed and determined the fractional inhibitory substances of fermentation and take preliminary analysis of inhibitory mechanism for the inhibitory substance. In this paper, we reported the following findings:1. We have screened eight antagonistic strains of Fusarium graminearum from24soil samples. After the inhibitory effect contrast, JC-07strain showed the strongest inhibitory effect and was selected as target antagonistic strain in this study. By morphological observation, physiological and biochemical characteristics determination and16S rDNA sequence analysis, the JC-07strain was identified as Bacillus amyloliquefaciens.2. Through temperature, pH, UV radiation sensitivity test of JC-07, we have obtained that the strain were tested steady stateat a temperature in the range40-60℃and a pH range of pH3.0-9.0, UV irradiation time for0.5-3hours, antibacterial substances within the variation range of the above conditions is relatively stable.3. Through the single factors analysis of the fermentation medium, fermentation temperature, fermentation time, rotation speed, and the initial pH in the medium and orthogonal experiment of fermentation time, fermentation temperature, rotation speed and medium initial pH four factors, we get results that JC-07strains producing antibacterial substances optimal combination of fermentation time72h fermentation, fermentation temperature37, shaking speed220r/min, medium initial pH8, and the impact of four factors on the fermentation effect the order of the fermentation temperature> the medium initial pH> fermentation time>shaking speed.4. By repeatedly ammonium sulfate salting-out, dialysis desalination, dextran column chromatography steps such as separation of the inhibitory protein, and the protein has a molecular weight of approximately56kD as measured by SDS polyacrylamide gel electrophoresis and Fermentation liquid antibacterial protein concentration of about1.67mg/mL, the protein does not contain benzenering, containing a sugar group, and the alpha-amino acid.5. By the study of the Inhibiting mechanism, we obtained that the inhibitory protein had teratogenic effects on Fusarium graminearum hyphae and spores. It can inhibit the germination of Fusarium graminearum’s spores, it has inhibition of biochemical reactions and energy transfer which the substrate is the reducing sugar and soluble protein or enzyme synthesis of Fusarium graminearum has a certain degree of inhibition.