乙草胺降解菌株枯草芽孢杆菌L3产芽孢条件的优化

为了对乙草胺降解菌株枯草芽孢杆菌(Bacillus subtilis)L3的产芽孢条件进行优化,以发酵液中芽孢形成率与总生物量为检测指标,首先通过单因素试验考察不同碳源、氮源、无机盐对菌株L3芽孢形成的影响,然后利用2个L16(43)正交试验分别得到菌株L3产芽孢的最佳培养基组合及最优发酵条件。结果表明,菌株L3产芽孢的最优培养基组成为:1%乳糖、3%玉米浆和0.1%Na H2PO4·2H2O;最优发酵条件为:培养基起始p H值7.5、种龄20 h、装液量30 m L(250 m L容器)。优化后,该菌株的芽孢形成率可达97.1%,总生物量达6.5×109cfu/m L。

Optimization of Spore Production Conditions of Acetochlor-degrading Strain Bacillus subtilis L3

L3,belonging to Bacillus subtilis,is an acetochlor-degrading strain. In order to improve the formation rate and quantity of its spores, the optimization of spore produced conditions of L3 was conducted. Spore formation rate and total biomass in the fermentation liquor were used as detection indexes in this test. Firstly,the factors influencing the production of spores of L3,such as carbon sources, nitrogen sources and inorganic salts,were investigated by single factor tests. And then two orthogonal tests at L16 ( 43 ) were used respectively to obtain the optimized medium combination and the fermentation conditions which were best for the spore formation of L3 . The results showed that the optimum medium composition was as follows:1% lactose,3% corn flour,0. 1% NaH2 PO4 ·2H2 O. The optimum culture conditions were as follows:initial pH of 7. 5,inoculated time of 20 h,filling capacity of 30 mL in 250 mL bottle. After optimization,Bacillus subtilis L3 had a spore production rate of 97. 1%,and the total biomass reached 6. 5 × 109 cfu/mL.