一株桑树内生拮抗菌的分离鉴定

Isolation and Identification of an Antagonistic Endophytic Bacterial Strain From Mulberry

从经过严格表面消毒的桑树根、茎、叶中分离获得内生细菌76株。以金黄色葡萄球菌(Staphylococcus aureus)作为指示菌进行拮抗菌的筛选,其中5个分离株具有抑菌活性,复筛选出抑菌活性及热稳定性最强的G21菌株。进一步研究表明G21菌株对家蚕病原真菌球孢白僵菌(Beauveria bassiana)、绿僵菌(Metarhizium)均具有较强的拮抗作用。该菌株的形态及部分生理生化特征为:革兰阳性,杆状,产芽孢,接触酶阳性,好氧。16S rDNA序列分析表明该菌株与芽孢杆菌(Bacillus)的同源性达到99.8%。综合以上鉴定结果确定G21菌株为芽孢杆菌。

76 endophytic bacterial strains were isolated from strictly surface disinfected mulberry tissues （root, stern and leaf）. Among them, 5 strains were found to have antagonistic activity against Staphylococcus au- reus. Further screening revealed that strain G21 had the highest antagonistic activity and thermal stability. It was also discovered that strain G21 had a strong antagonism to silkworm pathogenic fungi Beauveria bassiana and Metarhizium. Strain G21 is Gram positive, rod-shaped, able to form spores, positive in catalase-test, and aerobic. The result of 16S rDNA sequencing analysis indicates that it shared 99.8% identity with Bacillus. Therefore, strain G21 was identified as Bacillus based on the above results.