枯草芽孢杆菌斯氏亚种YC25发酵条件优化及防效测定

Fermentation condition optimization and biocontrol effect determination of Bacillus subtilis subsp. spizizenii YC25

摘要:

目的 通过优化枯草芽孢杆菌斯氏亚种YC25的发酵培养基及培养条件，提高其发酵水平，为后续该菌株的工业开发及应用提供理论基础。方法 以芽孢产量为指标，通过单因素试验筛选出最适的培养条件，在此基础上进行响应面分析，优化出最佳发酵培养基配方。采用盆栽防效试验测定优化后发酵液对烟草黑胫病和烟草镰孢菌根腐病的防治效果。结果 最佳发酵培养条件：30 ℃、180 r/min、接种量2%、装液量20%、发酵时间36 h。最佳发酵培养基组分：玉米淀粉15.53 g/L，豆粕粉8.70 g/L，KH₂PO₄ 0.50 g/L，MgSO₄ 0.92 g/L，CaCO₃ 0.50 g/L。在此条件下，芽孢产量为1.423 3×10¹⁰ CFU/mL。盆栽试验结果表明：稀释20倍的发酵液对烟草黑胫病的防效为77.88%，对烟草根腐病的防效为62.09%。结论 优化后的培养基能显著增加菌株YC25的芽孢量，并且施用YC25发酵液后，烟草黑胫病菌及根腐病菌病情指数显著降低，该研究为今后生防菌株YC25的菌剂开发生产及田间病害防治提供理论依据。

Abstract:

Objective To improve the fermentation performance by optimizing the fermentation medium and conditions of Bacillus subtilis subsp. spizizenii YC25, thereby providing a theoretical basis for the subsequent industrial development and application of the strain.Methods With the spore yield as the indicator, the optimal fermentation conditions were screened by single factor tests. On this basis, the response surface methodology was employed to optimize the fermentation medium. Pot experiments were conducted to evaluate the control effects of the optimized fermentation broth on tobacco black shank and tobacco Fusarium root rot.Results The optimum fermentation conditions were as follows: 30 ℃, 180 r/min, an inoculation amount of 2%, a liquid-loading volume of 20%, and fermentation time 36 h. The optimum fermentation medium was as follows: corn starch 15.53 g/L, soybean meal 8.70 g/L, KH₂PO₄ 0.50 g/L, MgSO₄ 0.92 g/L, and CaCO₃ 0.50 g/L. Under these conditions, the spore yield reached 1.423 3×10¹⁰ CFU/mL. The results of pot experiments showed that the control effects of the fermentation broth diluted by 20 times on tobacco black shank and tobacco Fusarium root rot were 77.88% and 62.09%, respectively.Conclusion The optimized medium could significantly increase the spore yield of strain YC25, and the disease indexes of tobacco black shank and tobacco Fusarium root rot were significantly reduced after the application of YC25 fermentation broth. This study provides a theoretical basis for the development and application of the biocontrol strain YC25 and the prevention and control of field diseases in the future.