宁夏枸杞内生细菌的多样性及其抑菌活性研究

【目的】对宁夏枸杞各药用部位内生细菌的分布特征、遗传多样性和抑菌活性进行分析。【方法】采用菌落计数和16S rRNA基因序列分析法研究枸杞内生细菌的分布特征、遗传多样性，采用琼脂扩散法测定其抑菌活性。【结果】从各药用组织器官中分离出内生细菌34株，隶属于7科11属，内生细菌的数量和群落组成存在明显的组织特异性，其数量表现为根皮>叶>花>果实，而多样性则表现为花>根皮>叶>果实。芽孢杆菌属为枸杞优势内生菌群，分布于所有组织中；抑菌实验结果表明有76.5%的内生菌对一种或多种病原菌的生长有抑制作用，芽孢杆菌属菌株R2、R7、L3和短波单胞菌属的R3拮抗番茄炭疽杆菌和玉米大斑病菌的能力较强，而多数菌株对大肠杆菌和金黄色葡萄球菌的抑制能力较弱。【结论】枸杞可培养内生细菌遗传多样性丰富，对植物病原菌有较强的抑制活性。

Diversity and antimicrobial activity of endophytic bacteria isolated from Lycium barbarum of Ningxia

Objective] The purpose of this study was to investigate the distribution, diversity and antimicrobial activity of endophytic bacteria of Lycium barbarum L. of Ningxia. Methods] The 16S rRNA gene sequencing and agar diffusion were employed to explore the diversity and antimicrobial activity of endophytic bacteria isolated from different organs and tissues of Lycium barbarum L.. Results] Total of thirty-four isolates were obtained. The result of diversity analysis showed that these isolates could be phylogenetically classified into 11 genera and 7 families, based on their 16S rRNA gene sequencing. The quantity and clonal composition of bacterial communities were distinct from various tissues. The quantity of endophytic bacteria in the different tissues was in order of roots > leaves > flowers > fruits; the diversity of bacteria was flowers > roots > leaves > fruits. Additionally, Bacillus spp. was a predominant species and was isolated in all tested tissues. Analysis of antimicrobial activity demonstrated that 76.5% of isolates had an antimicrobial activity against at least one of the five tested pathogenic bacteria, among which Bacillus R2, R7, L3 and Brevundimonas R3 displayed significant antimicrobial activity against the plant pathogens Colletotrichum nigrum and Exserohilum turcica. Of note, the majority of isolates showed weak inhibition effect against Escherichia coli and Staphylococcus aureus. Conclusion] Endophytic bacteria of Lycium barbarum L. are genetically diverse and most of them have a strong inhibitory activity against plant pathogenic fungi.