假单胞菌YL11对扩展青霉的抑制作用及其机理初探

【背景】苹果青霉病是由扩展青霉引起的一种重要的果实采后病害,影响果实品质导致苹果腐烂从而造成经济损失。【目的】研究假单胞菌YL11对扩展青霉的抑制作用和苹果采后青霉病的防治效果,并对抑菌机理进行初步探讨。【方法】以扩展青霉为供试菌株,研究不同浓度的假单胞菌YL11无菌发酵液对扩展青霉菌落直径、孢子萌发率、菌丝体干重、苹果损伤接种病斑直径扩展的影响,利用对电导率、核酸及蛋白释放量、AKP含量、SDH活性、ATP酶活性和ATP含量的影响对抑菌机理进行探究。【结果】假单胞菌YL11无菌发酵液能有效抑制扩展青霉生长,抑菌圈直径为22.33±0.27 mm,抑菌效价为71.67 mm/mL;能有效抑制孢子萌发,100%无菌发酵液对孢子萌发抑制率达到80.2%;对扩展青霉的生物量也有一定抑制作用,体积分数为100%时,菌丝体干重为4.7mg/mL,抑制率达到39.74%;无菌发酵液处理能有效抑制苹果青霉病病斑的扩展,3d时对病斑扩展的抑制率最大,达到47.1%;无菌发酵液处理均能引起电导率升高、胞内核酸和蛋白释放量增大、胞外AKP含量升高、SDH活性降低、ATP酶活性和ATP含量均降低,且随着发酵液浓度的增加效果越明显。【结论】假单胞菌YL11能显著抑制扩展青霉的生长,破坏细胞膜结构、降低能量代谢酶活性,从而扰乱扩展青霉的正常生长,对苹果青霉病有较好的生防效果,具有潜在的开发价值。

Initial study on inhibition of Penicillium expansum by Pseudomonas sp. YL11 and mechanism

[Background] Apple blue mold rot is an important fruit post-harvest disease that caused by Penicillium expansum, which affects the quality of the fruit and leads to the rot of the apple resulting in economic losses. [Objective] To study the inhibitory effect and explore the inhibition mechanism of Pseudomonas sp. YL11 on P. expansum. [Methods] We studied the effects of cell-free fermentation filtrate of Pseudomonas sp. YL11 with different concentration on the growth colony diameter, spore germination, mycelial dry weight of P. expansum and the lesion diameter of wounded inoculated apple fruit; We also explored impact of the conductivity, nucleic acid and protein release, AKP content, SDH activity, ATPase activity and ATP content to reveal the inhibitory mechanism. [Results] Pseudomonas sp. YL11 sterile fermentation broth effectively inhibited the growth of P. expansum. The diameter of inhibition zone was 22.33±0.27 mm and the inhibition titer was 71.67 mm/mL. It also could effectively inhibit spore germination. The inhibition rate of 100% aseptic fermentation broth to germination reached 80.2%. It had certain inhibition effect on the biomass of P. expansum. The dry weight of mycelium was 4.7 mg/mL and the inhibition rate reached 39.74% when the volume fraction was 100%. Moreover, aseptic fermentation fluid effectively inhibited extension of lesion diameter of blue mold of apple. The maximum inhibitory rate reached 47.1% at 3 d. In addition, aseptic fermentation broth treatment increased electrical conductivity, intracellular nucleic acid, protein release, extracellular AKP content and decreased SDH activity, ATPase activity and ATP content. The effect was enhanced by the fermentation broth concentration. [Conclusion] Pseudomonas sp. YL11 disturbed the normal growth of P. expansum by significantly inhibited the growth of P. expansum, destroyed the structure of cell membrane and reduced the activity of energy metabolism enzyme. It had a good better biocontrol effect to against blue mold of apple and had a potential development value.