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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,K2HPO43H2O 1.0 g/L,MgSO47H2O 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。
The Alternaria longipes strain was selected as the indicator for screening, and three strains of antagonistic Bacillus caldotentii were screened by plate co-culture and the filtrate of the fermentation supernatant. The bacterial growth inhibition rate (PIRG) of strain K11 was 63.64%, and the PIRG value of the fermentation supernatant filtrate was 67.44%. Pot experiments show that the bacteria has good antagonistic ability against tobacco brown spot disease. The identified strain K11 is Bacillus subtilis. The single factor experiments and orthogonal experiments were carried out to optimize the shake flask fermentation medium of K11 strain. The optimal fermentation medium was glucose 20.0 g / L, soybean meal 30.0 g / L, K2HPO43H2O 1.0 g / L and MgSO47H2O 0.1 g / L. The biomass of the biocontrol strain K11 was improved by 6.5 times, the biomass was as high as 1.28 × 1010 CFU / mL and the rate of sporulation was over 95%.