Isolation Of The Pathogen Causing Zanhuang Jujube Black Rot And Screening Of Antagonistic Microorganisms

This study was aimed at isolation, biological and physiological characteristics of the pathogen causing Zanhuang jujube black rot, and screening of antagonistic microorganisms against the pathogen.The Phoma sp.andAlternaria sp.were thought to be the major pathogen. By multible screening, we obtained antagonisticActinomycetesAC01, AC07 and antagonisticBacillus B01, B07, which had great practical signification in both research and production. The fermentation medium and optimum fermentation conditions were determined, also.The main results were as follows:1. The results of isolation and inoculation of pathogen showed:the average separation rates of Phoma sp. and Alternaria sp. was 35.67% and 40.00% from 2011 to 2013, respectively. They were the predominant pathogenic strains of Zanhuang jujube black rot.2. SCS was the optimal medium for the mycelial growth ofPhoma sp.; the glucose and carbamide was the optimal carbon and nitrogen source. The temperature for the pathogen growth was 24℃ and for sporulation was 32℃. The optimal pH for mycelial growth was pH 6-9 and for sporulation was pH 8. PDAwas the optimal medium for the sporulation; the optimal carbon and nitrogen source was glycerol and ammonium. The lighting conditions for the pathogen growth was continuous dark conditions and for sporulation was light and dark cycle.3. The result of biological and physiological characteristics ofAlternaria sp. shows that:PDA was the optimal medium for the mycelial growth; the glucose and enzymes was the optimal carbon and nitrogen source for the mycelial growth; The optimal pHfor mycelial growthwas 6-10 and for sporulation was 10;The temperature range for the pathogen growth was 24-32 ℃ and for sporulation was 32℃; PDA was the optimal medium for the sporulation, the optimal carbon and nitrogen sourcefor the sporulation was glycerol and mannitol; The lighting conditions for the pathogen growth was continuous dark conditions and alternating light and dark conditions and for sporulation was continuous dark conditions.4. The result of the study showed that strain Bacillus B01 and Actinomyces AC01 had obvious and stable antagonistic effect to Phoma sp.The optimum fermentation medium for strain B01 consists of sugar 20 g/L, peanut powder 26g/L, yeast powder 5.5g/L,0.3g/L KH2PO4, MgSO40.2 g/L, CaCO40.4g/L,0.02g/L MnSO4, FeSO40.02g/L. The optimum fermentation conditions were defined as follows:concentration of seed broth, 1.5-2×l07-108cfu/ml; inoculation amount,4%(V/V);the volume of media in a 250ml flask,20ml; initial pH at 6.0; fermentation temperature,24℃; and fermentation time,48h.The optimum fermentation medium forActinomyces AC01 consists of sorghum powder 42g/L, soybean mea112g/L, (NH4)2SO43.7g/L, CaCO4 3.2g/L, NaC11.7g/L, yeast powder2.0g/L. The optimum fermentation conditions were defined as follows:concentration of seed broth, 1.5-2×l07-108cfu/ml; inoculation amount,3% (V/V);the volume of media in a 250ml flask,50ml; initial pH at 7.0; fermentation temperature,28℃; and fermentation time,108h.5. The result of the study showed that strain Bacillus B07 and Actinomyces AC07 had obvious and stable antagonistic effect to Alternaria sp.The optimum fermentation medium for strain B07 consists of sweet potato powder,2g/L; beef extract, 10g/L; NaC1, 10g/L; and MnSO4,0.02g/L. The optimum fermentation conditions were defined as follows:concentration of seed broth,1.5-2×l07-108cfu/ml; inoculation amount,2%(V/V);the volume of media in a 250ml flask,40ml; initial pH at 7.0; fermentation temperature,28 ℃; and fermentation time,108h.The optimum fermentation medium for strain AC07 consists of maltose,57g/L; soybean meal,27g/L; (NH4)2SO, 1.7g/L; CaCO4, 2.2g/L;NaCl,1.7g/L and yeast powder,2.0g/L. The optimum fermentation conditions were defined as follows:concentration of seed broth, 1.5-2×107-108cfu/ml; inoculation amount,2%(V/V);the volume of media in a 250ml flask,40ml; initial pH at 7.0; fermentation temperature,28 ℃; and fermentation time,108h.