小麦全蚀病菌拮抗菌Bacillus methylotrophicusZ-9菌株产芽孢条件优化

甲基营养型芽孢杆菌(Bacillus methylotrophicus)Z-9菌株对小麦全蚀病病原菌有显著拮抗活性,以芽孢产率和活菌数为主要指标,采用单因素试验和正交试验对Z-9菌株摇瓶产芽孢条件进行优化,为其工业生产提供试验依据。通过单因素试验确定最佳碳源、氮源和无机盐分别为玉米粉、黄豆饼粉和MnSO_4·H_2O、Mg SO_4·7H_2O。通过正交试验确定最适培养基组分为玉米粉1.0%、黄豆饼粉2.0%、MnSO_4·H_2O 0.04%、MgSO_4·7H_2O 0.04%、Na_-2HPO_4·2H_2O 0.4%、Na H_2PO_4·2H2O 0.2%;最适发酵条件为:初始p H值7.5,250 m L三角瓶装液量50 m L,37℃培养36 h。优化后发酵液的芽孢数量为1.60×109cfu/m L,较优化前提高了13.7倍,芽孢产率达到96.5%。

Conditions Optimization for Spore Production of Antagonistic Bacterium Bacillus methylotrophicus Z-9 against Wheat Take-all Disease

Significant antagonistic activity of strain Bacillus methylotrophicus Z-9 against wheat take-all disease was shown. In order to optimize spore production conditions of the strain Z-9,researches were done by single-factor tests and orthogonal tests with number of viable cells and spore production rate as indexes. The best carbon source, nitrogen source and inorganic salt were corn flour, soybean meal, and MnSO4 · H2 O, MgSO4 · 7H2 O, respectively, by the single factor experiments. The optimum medium components were determined as corn flour 1. 0%,soybean meal 2. 0%,MnSO4 ·H2 O 0. 04%,MgSO4 · 7H2 O 0. 04%, Na2 HPO4 · 2H2 O 0. 4%, NaH2 PO4 · 2H2 O 0. 2%, and the optimum fermentation conditions were determined as initial pH value of 7. 5, medium volume of 50 mL in 250 mL flask, cultivating at 37 ℃ for 36 h by the orthogonal experiments. The spore yield reached 1. 60 × 109 cfu/mL, which was improved by 13. 7 times,compared to the result before optimization,and the spore production rate reached 96. 5% under the optimum conditions.