一株内生拮抗细菌的分离鉴定及其抗菌机理研究

Isolation,identification and antimicrobial mechanism of an endophytic antagonistic bacterium

本研究通过平板稀释法、平板对峙法从核桃根部皮层筛选出一株对核桃根腐病有拮抗作用的内生菌株1A,通过形态特征测定、理化特性分析和16SrDNA序列分析鉴定该菌为芽胞杆菌(Bacillus sp.),GenBank序列登录号为KJ865856;其抑菌特性研究结果表明:该拮抗菌对核桃根腐病菌有显著的抑制效果,抑菌率达63.33%;此外,该菌对板栗疫病菌等几种不同的林木病原菌均有较强的抑制作用。抗生机理研究结果表明,该菌株通过分泌蛋白酶和纤维素酶降解真菌细胞壁中蛋白质和纤维素,破坏病菌菌丝,病菌生长受到抑制。该拮抗菌能够显著抑制核桃根腐病菌菌丝生长和孢子萌发,孢子萌发抑制率达74.89%,病菌菌丝表现为菌丝扭曲、断裂,分支增多并缠绕,菌丝颜色加深等。盆栽生防效果研究显示,该拮抗菌对各组核桃根腐病具有显著的防治效果,采用该拮抗菌预处理具有相对较好的生防效果。

The endogenic bacterium strain 1A from walnut root was found to have antagonistic effect on Fusarium solani. Strain 1A was identified as Bacillus sp. based on the observation of morphological features, the analysis of physiological and biochemical characteristics, and the 16S rDNA sequences. The GenBank accession number was KJ865856. The antimicrobial research results showed that strain 1A had a significant inhibitory effect on F. solani and the inhibition rate reached to 63.33%. In addition, strain 1A had a significant inhibitory effect on several forest pathogenic bacteria such as Cryphonectria parasitica. The result of antibiosis mechanism indicated that strain 1A could produce protease and cellulase to degrade the protein and cellulose composition of fungal cyto- derm, and damage F. solani mycelia to inhibit the growth of F. solani. The strain 1A could strongly inhibit the hyphal growth and spore germination of F. solani, and the inhibition rate of spore germination was 74.89%. The mycelia were distorted, fractured, with increased and winding branches and deepened color. The antagonistic bac- terium strain 1A showed good control potential against walnut root rot in the semi-field experiment and the pre- treatment of the antagonistic strain 1A had a better biocontrol effect.