ε-聚赖氨酸对樱桃采后病原菌橘青霉和链格孢菌的抑菌作用研究

Inhibitory effects of ε-polylysine on Penicillium citrinum and Alternaria alternata inoculated on fresh cherry

目的 探究ε-聚赖氨酸(ε-polylysine,ε-PL)对樱桃果实采后病原菌橘青霉(Penicillium citrinum)和链格孢菌(Alternaria alternata)的抑菌作用和抑菌机制。方法 本研究测定100、200、400、800 mg/Lε-PL处理对2种病原菌菌丝生长、孢子萌发、细胞膜透性的影响;采用扫描电子显微镜(scanningelectron microscope,SEM)观察ε-PL处理对病原菌孢子的形态的影响;并在樱桃果实上接种2种病原菌,观测ε-PL处理在果体上的抑菌作用。结果 ε-PL对P.citrinum和A.alternata菌落直径扩展的抑制效果随着处理浓度的增加而提高,大于200 mg/L的ε-PL显著抑制孢子萌发;经ε-PL处理后2种病原菌的电导率、OD_(280nm)、OD_(260nm)均显著升高(P<0.05),细胞膜通透性增加,蛋白质和核酸等内容物渗漏,细胞膜完整性遭到破坏;经SEM观察发现,ε-PL处理后P. citrinum和A. alternata孢子变形、凹陷,失去正常的细胞形态;大于400 mg/L的ε-PL处理能抑制樱桃果实上的病斑扩展。结论 ε-PL处理可以破坏P. citrinum和A. alternata的细胞膜,导致细胞内容物外渗,使菌丝生长和孢子萌发受阻,进而抑制病原菌的生长,同时,ε-PL处理可以抑制P.citrinum和A. alternata对果实的侵染,在樱桃的采后保鲜方面具有一定的防腐效果。

Objective To explore the antimicrobic effects and mechanism of ε-polylysine(ε-PL) against Penicillium citrinum and Alternaria alternata on postharvest cherry fruits. Methods The effects of 100、200、400、800 mg/L ε-PL treatments on mycelial growth, spore germination and cell membrane permeability of two pathogens were determined, the morphology of pathogen spores after ε-PL treatments was observed by scanning electron microscope(SEM). Two kinds of pathogens were inoculatedon cherry fruits to observe the antibacterial effects of ε-PL on the fruit. Results The inhibitory effects of ε-PL on the mycelial diameter of P. citrinum and A. alternata with increasing concentration, and the concentration of ε-PL above 200 mg/L significantly inhibited spore germination. The conductivity, OD_(280nm) and OD_(260nm) of two pathogens increased significantly(P<0.05), the membrane permeability was increased, the content of protein and nucleic acid was released, and the integrity of cell membrane was destroyed after ε-PL treatments. SEM observation showed that spores of P. citrinum and A. alternata were deformed, collapsed and lost normal cell morphology. ε-PL treatment over 400 mg/L could inhibit the spread of diseased spots on cherry fruits. Conclusion ε-PL treatment can destroy the cell membrane of P. citrinum and A.alternata, cause cell contents leakage, hinder mycelium growth and spore germination, and then inhibit the growth of pathogens. At the same time, ε-PL treatment can inhibit the infection of P. citrinum and A. alternatato fruit, which has a certain antiseptic effect on postharvest preservation of cherries.