烟草赤星病拮抗芽胞杆菌的筛选及培养基优化

以赤星病原菌Alternaria longipes为筛选指示菌，采用平板共培养初筛和发酵上清滤液复筛的方法，筛选了烟草赤星病拮抗芽胞杆菌3株。其中菌株K₁₁的菌体径向生长抑制率（PIRG）为63.64%，发酵上清滤液的PIRG值达67.44%。盆栽试验证明，该菌对烟草赤星病具有良好的拮抗能力。经鉴定菌株K₁₁为枯草芽胞杆菌（Bacillus subtilis）。由单因素实验和正交实验优化得到了K₁₁菌株生物量较高的摇瓶发酵培养基配方：葡萄糖20.0 g/L，豆粕30.0 g/L，K₂HPO₄·3H₂O 1.0 g/L，MgSO₄·7H₂O 0.1 g/L。优化后生防菌株K₁₁的生物量比对照提高6.5倍，生物量高达1.28×10¹⁰ CFU/mL，芽胞形成率在95%以上。

Screening and Medium Optimization of Antagonistic Bacillus Against Tobacco Brown Spot Disease

Three strains were selected as the Bacillus agtagonists against tobacco brown spot disease from 93 strains stored in our lab, the strain K₁₁ showed the highest percentage inhibition of radial growth (PIRG). The PIRG was 63.64% by the dual culture while 67.44% in culture filtrate tests. According to the physiological and biochemical characteristics, the strain K₁₁ was identified as Bacillus subtilis. Based on the single factor experiments and orthogonal experiments for K₁₁, an optimum fermentation medium for biomass production in flasks composed of glucose 20.0 g/L, soybean meal 30.0 g/L, K₂HPO₄·3H₂O 1.0 g/L, and MgSO₄·7H₂O 0.1 g/L. Under the optimum fermentation conditions, the highest biomass yield was 1.28×10¹⁰ CFU/mL, which was 6.5 times of the initial KMB medium, and the sporulation rate reached as much as 95%.