Antagonistic action of Bacillus subtilis strain fmbj on the postharvest pathogen Rhizopus stolonifer

The antagonistic activities of Bacillus subtilis fmbj against the Rhizopus stolonifer pathogen causing peach soft rot disease were studied in this paper. Bacillus subtilis fmbj exhibited a high antifungal effect on the mycelium growth, sportulation, and germ tube elongation of R. stolonifer with the inhibition rate of 86.5% and 97.42%, respectively, spore germination rate of 20% under antagonist strain concentration of 10⁸ CFU/mL. By using of scanning electron microscope (SEM) and transmission electron microscope (TEM), it was observed that B. subtilis fmbj strain strongly induced morphological abnormalities of R. stolonifer and destroyed structure of hypha and spore. When hypha cell wall of R. stolonifer was damaged, the organelles and cytoplasms inside cell would exude, which led to cell death.