Abstract: In order to effectively control soil-borne diseases of cucumber, 256 strains of bacteria were isolated from the rhizosphere soil of cucumber, and an antagonistic strain ZM-1 was screened by the plate confrontation method. Based on physiological, biochemical and molecular biological analysis, the strain ZM-1 was identified to be Pseudomonas aeruginosa. The inhibition rate of the strain against Fusarium oxysporum f. sp. cucumebrium and Phytophthora drechsleri were 62.80% and 65.58%, respectively. The strain can produce a variety of antibacterial substances, such as cellulase, siderophore and so on. The fermentation optimization of the strain was carried out by orthogonal experiment method and single factor method. After optimization, the bacterial amount in the fermentation broth of the strain can reach more than 1×10¹⁰cfu/ml. The optimal fermentation conditions were 5 g/L of sucrose, 10 g/L of tryptone, 10 g/L of K₂HPO₄, pH value of 7.5, continuous fermentation for 48 h, with 2% inoculation quantity under temperature of 25 ℃. Pot experiment showed that the relative control efficacies of strain ZM-1 against cucumber fusarium wilt and cucumber blight were 53.97% and 51.11%, respectively. The above results indicate that the antagonist strain ZM-1 has potential for development and application in the control of soil-borne diseases of cucumber.

Key words: cucumber blight, cucumber Fusarium wilt, Pseudomonas aeruginosa, identification, fermentation, biological control