产挥发性杀线虫物质韦氏芽孢杆菌MC67菌株培养条件的优化

采用液体培养,研究了18种碳源、18种氮源成分对韦氏芽孢杆菌Bacillus weihenstepha-nensis菌株MC67产挥发性物质杀线虫活性的影响。以单因素分析法,确定了MC67菌株杀线虫活性的最佳碳源和氮源分别为麦芽糖和酵母膏。采用Plackett-Burman设计法,对影响菌株MC67杀线虫活性的主要因素进行筛选,确定影响该菌株发酵液挥发物杀线虫活性的4个重要因子依次为麦芽糖、酵母膏、温度和pH值。采用响应曲面法研究4个显著因子的最佳水平,通过对二次多项回归方程求解得知,当麦芽糖10.6g/L、酵母膏0.66g/L、培养温度29.6℃、pH值6.6时,菌株发酵液挥发物杀线虫活性的预期值为99.1%。对模型培养基验证的结果表明,该菌株对松材线虫的杀线虫活性为98.2%,接近预期值。

Optimization of the Culture Condition for Bacillus weihenstephanensis Strain MC67 Producing Nematicidal Volatiles

In liquid culture, 18 kinds of carbon and 18 kinds of nitrogen resources were selected for best nutritional agents. The effects of nutrition on the volatiles of Bacillus weihenstephanensis strain MC67 with highest nematicidal activity to Bursaphelenchus xylophilus were determined by single factor analysis. The best carbon and nitrogen resources were maltose and yeast extract, respectively. Plackett-Burman design and response surface analysis were used to optimize the medium constituents and fermentation conditions of B. weihenstephanensis. The important factors were determined as follows： maltose, yeast extract, pH value and temperature. In the second phase of the optimization process, a response surface methodology （RSM） was used to optimize the above critical factors, and to find out the optimal concentration levels and fermentation conditions. By solving the quadratic regression model equation using appropriate statistic methods, the optimal level of the variables were determined as： maltose 10.6 g/L, yeast extract 0.66 g/ L, culture temperature 29.6 ℃ and pH value 6.6. In the most suitable condition, the nematicidal activity of MC67 could reach to 98.2 %, which validated the theoretical value 99.1% .