Abstract:In order to evaluate control efficacy to damping-off on cucumber of antagonistic bacterium strain BMP-11, the inhibition effect to the pathogen of Pythium aphanidermatum were tested using dual culture method and optical microscope observation, plant growth promotion and biocontrol tests were also carried with ferment broth of BMP-11; and to determine its classification status, identification experiments were proceed by morphology and culture feature observation, and physiological and biochemical characteristics determination and 16S rDNA sequences assay. The results showed that strain BMP-11 had strong inhibitory action against Pythium aphanidermatum. It could make the cell wall of the mycelium broken, the protoplasm condensed and leaked, and inhibit the hypha form oocyte. In addition, there had no inhibition on the germination rate of cucumber seed, and it could also increase the emergence rate and improve the growth of cucumber seedlings. The disease control effect of BMP-11 on cucumber damping-off was 62.2% in plot test in greenhouse, which was similar to that of the commercial fungicide propamocarb. BMP-11 had the nearest evolutionary distance with Paenibacillus polymyxa GBR-1 by phylogenetic tree of 16S rDNA sequences, combining with its results of morphological, culture and biochemical pro- perty analysis, it was identified as Paenibacillus polymyxa.