| There are a lot of beneficial microorganisms in the soil, take the purpose of controling plant diseases, antagonistic fungi was screened from soil. The culture conditions and antibacterial activity were studied on this strain.Using dual culture plate antagonism assay method, taking ten more kinds of plant pathogens as materials, the inhibitory spectrum was determined and the results showed the broad spectrum of antagonism activity. This antagonistic fungi was named as Acremonium persicinum by the methods of morphology and 18S rDNA sequencing. The results of culture conditions on this strain showed:the optimum natural medium for mycelial growth was PDA. The effect of different carbon, nitrogen source and pH, temperature and inorganic ions on the mycelial growth was studied under the based medium of Czapek medium:optimum carbon source was sucrose, nitrogen source was tryptone. Cultivate under the congdition of pH 8.5 and temperature 30℃; the mycelium growth rate was increased, adding inorganic ions Zn2+ can also improve the mycelium growth.In view of the antagonism activity of this strain fermentation, taking Alternaria solani, Stemphylium solani and Rhizoctonia solani as indicator pathogens, the fermentation conditions were optimized by measuring the mycelial growth rate. The results show that:the inhibitory ability of its fermentation was best when cultured this strain for 15-20 days under the congdition of pH 7.0, temperature of 28℃ and 160rpm.The effect of different concentrations of Acremonium persicinum fermentation on conidia germination and mycelial growth of Helminthosporium carbonum were studied, the results show that:on mycelium growth inhibition, the inhibition rate can be up to 100% under the concentration of 50% Acremonium persicinum fermentation, the inhibition rates between different concentrations and different concentration with the control were also significant (P=0.05); On spore germination experiments, spore germination rate of Helminthosporium carbonum was decreased treated by Acremonium persicinum fermentation, the germination percentage was only 24% after treated by the concentration of 90% fermentation and the inhibition rate was up to 66.67%, the EC50 of fermentation was approximately 68 ml·100 mL-1. The spores treated by fermentation were teratogenic and could not develop properly. Measuring the stability of the Acremonium persicinum fermentation showed:the antagonistic ability was stable to heat, save time and light, but unstable to protease.Antibacterial active substance on the Acremonium persicinum fermentation was preliminary separated, using the methods of organic solvent extraction and ammonium sulfate precipitation. The results showed that: the active substance was in raffinate phase of petroleum ethe, and could be precipitated by ammonium sulfate, the strongest inhibition activity was under the ammonium sulf condition of 30%and 50%. The activity material of Acremonium persicinum fermentation was think as protein initially. The effect of Acremonium persicinum fermentation on seed germination and enzyme activity during seed germination was found by soybean materials:the germination rate and seed enzyme activities of soybean seeds were changed differently treated by different concentrations of Acremonium persicinum fermentation. The seed germination was promoted by the concentration of 60% fermentation, and its rate was up to 85%; Germination potential and germination index reached the highest value under the concentration of 60%fermentation, were 43% and 18% respectively; The enzymatic assays results showed that:antioxidant activity was different under different concentrations of Acremonium persicinum fermentation, the POD, CAT and SOD enzyme activities were 683U,160.67U and 301U, respectively, highest in the concentration of 60% fermentation, but CAT and SOD activities were 97.54U and 198.23U, respectively, lowest in the concentration of 80% fermentation, for POD the lowest level was 383.67U, in the concentration of 40% fermentation. |
PDF Full Text Request