Study Of Isolation And Identification Of Endophytic Antagonistic Bacteria Against Alternaria Panax And Possibility Of Compound With Fungicides

From five Chinese herbs,82endophytic strains were isolated and55strains are endophytic antagonistic bacterium. Antifungal rate of five antagonistic bacteria against Alternaria panax all above50%, As a result of screening efficient antagonistic bacteria by laboratory confrontation-culture, the strain BJ33from ginseng roots revealed a strong antagonistic activity against Alternaria panax with80.00%of antifungal rate.According to the phenotypic property, physiological and biochemical characteristics combined with16S rDNA sequence analysis, the Strain BJ33was identified as Bacillus myloliquefaciens.This experiment adopts5kinds of Chinese herbal medicine plant material islote bio-control bacteria against Alternaria panax Whetz, and screening one effective antagonistic bacterium strain, studied the bacteriostatic activity of the effective strains against Alternaria panax, and compounded the strain with5kinds of fungicide. Results are as follows:Strain BJ33exhibited strong inhibition effects on mycelium growth of six plant pathogens examined in this study. Strain BJ33has strong antifungal activity under conditions with the temperature from15℃to35℃and the pH value from5to11. Inhibitory effect of strain BJ33does not change after short time UV irradiation, Strain BJ33still have strong inhibitory effect in the circumstance of nutritional stress. Strain BJ33can make Alternaria Panax cell abnormal and inhibited conidial production.Fermentation concentrate of Strain BJ33exhibited strong inhibition effects on mycelium growth of six plant pathogens in this study. It has strong antifungal activity under conditions with the temperature from15℃to35℃and the pH value from5to11. It maintained stable antifungal activities under high temperature, ultraviolet radiation, protease treatment. Fermented concentrate of strain BJ33has good storage stability, after store30days. The inhibitory effect keep stable after changed pH of the fermented concentrate treatment. The fermentation concentrate make Alternaria Panax spore abnormal,it inhibited germination and germ tube elongation.Strain BJ33compound with five fungicides showed, affect of Polyoxin on the growth of strain BJ33is the smallest among the five fungicide, compounding results also showed that the inhibitory effect on Alternaria panax will be enhanced. Followed by Difenoconazole and Iprodione, although both have a certain little negative effects impact on growth of strain BJ33, but will not reduce the inhibitory effect of strain BJ33on Alternaria panax, there inhibitory effect on Alternaria panax increased, too. Chlorothalonil and Mancozeb have a very strong inhibition to the growth of strain BJ33, it is not suitable to compound with the strain BJ33.