芽孢杆菌hjt6的鉴定、生长特性及其对瓠瓜灰霉病菌的拮抗效果

Identification and growth characterization of Bacillus sp. hjt6 with antagonistic effects on Cladosporium tenuissimum causing gray mold disease of bottle gourd

摘要:

【背景】由极细枝孢(Cladosporium tenuissimum)引起的灰霉病是设施瓠瓜上非常普遍的一种真菌性病害，常常造成巨大经济损失。【目的】对瓠瓜灰霉病菌具有明显拮抗活性的菌株hjt6进行鉴定、生长特性和抑菌活性评价，为瓠瓜灰霉病的生物防治提供菌种资源。【方法】通过形态学、生理生化测定、16S rRNA基因序列和gyrB基因测序分析对菌株hjt6进行鉴定；通过生长曲线、温度、pH和耐盐度等测定菌株hjt6的生长特性；采用菌丝抑制法测定该菌株的广谱抗性效果；通过平板拮抗、共培养和离体果实回接等测定菌株hjt6对灰霉病菌的防治效果。【结果】菌株hjt6鉴定为贝莱斯芽孢杆菌；在10−50 ℃时均能生长，30 ℃为最适生长温度，在pH 5.0−9.0时均能生长，pH 7.0时生长最好，在0−10% NaCl浓度下均能生长；菌株hjt6对8种作物病原菌均具有一定程度的抑制作用，抑制率为57.38%−82.18%；在平板上对灰霉病菌的抑制能力为“++++”，抑制率为71.53%，共培养能降低灰霉病菌菌丝质量77.31%，离体果实回接防效高达92.63%。【结论】菌株hjt6对瓠瓜灰霉病菌具有较好的拮抗效果，可作为拮抗灰霉病菌的菌种资源。

Abstract:

[Background] The gray mold disease caused by Cladosporium tenuissimum is a common fungal disease infecting protected bottle gourd, often resulting in serious economic losses. [Objective] To identify strain hjt6 with antagonistic activity against the gray mold disease of bottle gourd and evaluate the growth characteristics and antifungal activity of the strain, so as to provide microbial resources for the biocontrol of the gray mold disease of bottle gourd. [Methods] Strain hjt6 was identified based on morphological, physiological, and biochemical characteristics and 16S rRNA gene and gyrB gene sequences. The growth curve of the strain was established, and the temperature, pH, and salt tolerance was examined. The broad-spectrum antagonistic effect of this strain was evaluated by the mycelial inhibition assay. Plate confrontation, co-culture, and detached fruit re-inoculation were conducted to assess the disease control efficacy of strain hjt6 against C. tenuissimum. [Results] Strain hjt6 was identified as Bacillus velezensis. It grew within a temperature range of 10 ℃ to 50 ℃, with an optimal growth temperature of 30 ℃. It could grow within the range of pH 5.0–9.0, with pH 7.0 being the most suitable. The strain tolerated 0% to 10% NaCl. Strain hjt6 exhibited inhibitory activities against eight crop pathogens, with the inhibition rates ranging from 57.38% to 82.18%. It showed an inhibitory ability of “++++” and an inhibition rate of 71.53% against C. tenuissimum on plates. The co-culture results showed that the strain hjt6 reduced the mycelial mass of C. tenuissimum by 77.31%, and achieved the control efficacy of 92.63% on the detached fruits inoculated with the pathogen. [Conclusion] Strain hjt6 demonstrates promising antagonistic effects against the gray mold disease of bottle gourd and could serve as a valuable microbial resource for the biocontrol of this disease.