Screening Of Actinomycetes Against Fusarium Oxysporum F.sp. Cubense And Identification Of Strain Da03047 And Da04010

Fusarium wilt of banana is one of the most destructive worldwide diseases of banana, caused by Fusarium oxysporum f. sp. cubense (FOC), and is badly endangering the production of banana. Anti-fusarium wilt breeding, chemical and planting management are the present worldwide solutions to control this disease. However, there is no ideal solution among them. Thus it is necessary and urgent to find a better one.In this paper, 28 antagonistic strains against Fusarium oxysporum f. sp. cubense were isolated from soil samples collected from Dongzhaigang mangrove, Sanjiang mangrove, Jianfeng Mountain, and banana orchard in Jinjiang and Huangliu. From them strain Da03047 and Da04010 possessed prominent bioactivity and genetic stabilization, and were further studied.By studying the morphology, physiological and biochemical properties, 16S rDNA and phylogenetic tree, the results showed that strain Da03047 was proposed as Streptomyces griseocarneus and strain Da04010 as Streptomyces cyaneogriseus.The best optimal liquid fermentation medium components and fermentation conditions of Da03047 and Da04010 were obtained. The optimum culture medium components of Da03047 contained glucose 1%, sucrose 0.5%, corn powder 0.5%, soybean powder 0.5%, K2HPO4 0.05%; The optimum fermentation conditions of Da03047 were initial pH7.0, seed age 48h, 10% inoculation amount, the size 75mL in 250mL Erlenmeyer flask at 200 r/min and 28℃for 5d. And the optimum culture medium components of Da04010 contained glucose 2.5%, glycerol 3%, corn powder 0.5%, soybean powder 0.5%, K2HPO4 0.05%; The optimum fermentation conditions of Da04010 were initial pH7.0, seed age 48h, 10% inoculation amount, the size 100mL in 250mL Erlenmeyer flask at 200 r/min and 28℃for 5d.The stabilities of the antibacterial compounds of strain Da03047 and Da04010 were studied, the results showed the bioactive substance of Da03047 has heat stability, light stability, but not be stable at acid (pH<4.0) or alkali (pH>8.0) condition. And the bioactive substance of Da04010 was stable at acid condition (pH1.0~8.0), but not stable at alkali (pH>8.0), heat or light condition.