Selection,Identification and Characterization of Antagonistic Bacteria against Plant Soilborne Pathogens

From rhizosphere soil samples of healthy plants in heavy disease fields of medicinal herbs root rot and tobacco fields,10 isolates were selected based on their antagonistic activities to Fusarium oxysporum and other soilborne pathogens by confront cultivation.Among them,the strain DY-7 had strong antagonistic activity against most soilborne pathogens,and the inhibition rate arrived at 96.14% to F.oxysporum on Polygonum multiflorum,indicating that some antagonistic substances existed in the culture.DY-7 was selected to study on the characteristics of the antagonistic substances,and the results showed that they were of certain light,thermal and acid stability.Based on observation of the morphological features and a series of physiological and biochemical experiments,DY-7 was identified as Bacillus subtilis.