内生菌螺旋毛壳抗生素和水解酶的协同抗真菌作用

 生防因子螺旋毛壳(Chaetomium spirale) ND35生长于含立枯丝核菌(Rhizoctonia solani)菌丝细胞壁制备物的SM培养基中,从培养滤液提取的粗酶液强烈抑制Valsa sordida、Valsa mali、Glomerella cingulata和Curvulavia lunata病原真菌的菌丝生长和孢子萌发。经DNS法检测,粗酶液同时具有β-1,3-葡聚糖酶(包括内切和外切酶)和几丁质酶活性,分别为0.19 U.mg-1和0.09 U.mg-1。生长于3%玉米粉浸渍液的螺旋毛壳ND35的培养滤液也能抑制上述病原菌的菌丝生长和孢子萌发。离体条件下检测了ND35产生的一纯化的具有分子量为73 kD的内切β-1,3-葡聚糖酶(GLUC73)和一纯化的抗生素对苹果炭疽病菌的分生孢子萌发和芽管延长的抑制效果。当内切β-1,3-葡聚糖酶使用浓度为180 μg·mL^-1时,抑制了测试真菌的孢子萌发,造成细胞壁的改变,导致了菌丝顶端的破裂;抗生素的有效抑菌中浓度ED₅₀为1.75 μg·mL^-1。单独应用时,1.0 μg·mL^-1的抗生素或40 μg·mL^-1的内切β-1,3-葡聚糖酶没有或仅有很低的抑菌效果;两者组合导致孢子萌发约78%受抑制。甚至10 μg·mL^-1的内切β-1,3-葡聚糖酶也使1.5 μg·mL^-1抗生素的抑菌作用从低于25%增加到超过50%的抑菌效果。此外,80 μg·mL^-1的内切β-1,3-葡聚糖酶使1.0 μg·mL^-1抗生素的抑菌活性从0%提高到90%。抗生素和β-1,3-葡聚糖酶的协同抗菌活性可能在内生菌螺旋毛壳的植病生防中起重要作用。

Synergistic Antifungal Activity of Antibiotics and Hydrolytic Enzymes from Endophytic Chaetomium spirale ND35

The culture filtrate from biocontrol agent endophytic Chaetomium spirale ND35 grown in the SM medium containing cell wall preparation (CWP) of Rhizoctonia solani strongly inhibited mycelial growth and conidial germination of different phytopathogenic fungi including Valsa sordida, V. mali, Glomerella cingulata and Curvulavia lunata. The culture filtrate possessed activities of β-1,3-glucanases (endo-glucanase and exofiltrates from C. spirale ND35 grown in 3% corn steep power broth inhibited spore germination and mycelial growth of these pathogens. The inhibitory effect of a pure endo-β-1,3-glucanase ( GLUC73 ) in about 73 kD and a pure antibiotic from C. spirale ND35 on the germination of conidia and germ tube elongation of G. cininhibited spore germination of the test fungus and caused cell wall damage, resulting in bursting of hyphal tips.mL -1 of endo-β-1,3-glucanase had no or only a very low inhibitory effect. Their combination resulted in about 0% to 90%. Synergistic antifungal activity of antibiotic and endo-β-1 ,3-glucanase may play a role in biological control by endophytic C. spirale ND35.