枯草芽孢杆菌Xi-55液体发酵条件的优化及防治稻曲病试验

Optimization of liquid fermentation conditions of Bacillus subtilis Xi-55 and controlling to rice false smut

通过单因素试验和正交试验，对枯草芽孢杆菌（Bacillus subtilis）Xi-55的液体发酵培养基和工艺条件进行了优化，确定了在500mL锥形瓶中发酵培养基的最佳培养基为：蛋白胨3％，甘油1．0％，K2HP040．05％，MgSO4·7H200．15％；最适发酵条件为：时间36—48h，温度28～30℃，初始pH为7，接种量2％，装液量100mL／500mL锥形瓶。20L发酵罐扩大培养的初始pH为7．2，发酵温度28℃±0．5℃，通气量10L／min，搅拌转速180r／min，罐压0．05-0．06MPa，发酵终止在44h前，最佳放罐时间为40～44h，此时发酵液中的细菌含量为5．06×10^10efu／mL。小区试验显示，枯草芽孢杆菌Xi-55发酵液对稻曲病的防治效果为63．22％。

By single factor experiment and orthogonal experiment, the liquid fermentation medium and technological conditions of Bacillus subtilis Xi-55 were optimized. The results showed that optimum medium formula was peptone 3 %, glycerine 1.0 %, K2HPO4 0.05 % , MgSO4 · 7 H2O 0.15 %. The favorable fermentation condition was determined：time 36 -48 h, temperature 30℃ ,initial medium pH value 7,inoculation amount 2 % ,pack amount 100 mL/500 mL triangle bottle. The magnifying culture in 20 L fermentation tank was conducted, the growth peak of Xi-55 appeared in 36 h, optimum cultivating time 40 - 44 h, and the obtained bacterium amount was up to 5.05 × 10^10 cfu/mL in fermentation liquid. In the field plots,the liquid fermentation of Bacillus subtilis Xi-55 controlled the rice false smut strongly.