贝莱斯芽孢杆菌A4的发酵条件优化及生防效果评价

Optimization of fermentation conditions and evaluation of biocontrol efficacy of Bacillus velezensis A4

摘要:

背景 贝莱斯芽孢杆菌(Bacillus velezensis)是芽孢杆菌中的代表性生防菌，在植物病害方面表现出优良的防治效果。目的 探索发酵培养基和发酵条件对发酵液抑菌效果的影响。方法 以灰霉菌(Botrytis cinerea)为抑制对象，以菌落直径作为评估指标，采用单因素和响应面法对发酵培养基和发酵条件进行筛选和优化，确定该菌株的最优培养基组分及最优培养参数。结果 该菌株的最佳发酵培养基为BPY培养基，最佳碳源、氮源分别为蔗糖(12.5 g/L)、丝氨酸(12.5 g/L)，最佳发酵条件为接种量3%，pH 8.0，转速93 r/min。相较于优化前的发酵液，优化后的发酵液使灰霉菌菌丝平板菌落直径下降12.34%，菌丝干重下降43.98%；番茄果实病斑直径降低24.44%，病斑面积降低39.71%。结论 本研究优化了贝莱斯芽孢杆菌的发酵培养基和发酵条件，显著提升了贝莱斯芽孢杆菌发酵液的抑菌效果，为贝莱斯芽孢杆菌A4菌株菌剂的开发和应用提供了理论依据。

Abstract:

Background Bacillus velezensis is a representative biocontrol bacterium, demonstrating excellent efficacy in controlling plant diseases.Objective To investigate the effects of fermentation medium composition and fermentation conditions on the biocontrol efficacy of the fermentation broth of B. velezensis strain A4.Methods Using Botrytis cinerea as the target pathogen and colony diameter as the primary evaluation indicator, we employed single-factor experiments coupled with response surface methodology to optimize the medium composition and fermentation conditions.Results The optimal fermentation medium was BPY medium, with the optimal carbon and nitrogen sources being sucrose (12.5 g/L) and serine (12.5 g/L), respectively. The optimal fermentation conditions were an inoculum size of 3%, initial pH 8.0, and a shaking speed of 93 r/min. Compared with the fermentation broth produced under pre-optimization conditions, the fermentation broth produced under optimized conditions significantly inhibited the growth of B. cinerea, decreasing the mycelial colony diameter by 12.34%, the mycelial dry weight by 43.98%, and the diameter and area of disease spots on tomato fruits by 24.44% and 39.71%, respectively.Conclusion We successfully optimized the fermentation medium and conditions for B. velezensis strain A4. This optimization significantly enhanced the biocontrol efficacy of its fermentation broth against B. cinerea. Our findings provide a theoretical foundation for the development and application of microbial agents based on B. velezensis strain A4.