铁皮石斛茎可培养内生细菌的多样性及其抑菌作用

Diversity of culturable endophytic bacteria in stems of Dendrobium officinale and their antibacterial effects

  • 摘要: 从铁皮石斛 (Dendrobium officinale) 茎中分离内生细菌,并探究其抑菌活性及其次生代谢产物. 该研究对传统的内生细菌分离方法进行改良,并对所分离菌株的16S rDNA 基因进行测序与鉴定,采用对峙法和滤纸片扩散法对内生细菌及其发酵粗提物进行抑菌实验. 最后,利用不同色谱技术分离、纯化优良抑菌活性菌株的次生代谢产物. 结果表明,使用改良方法发现了 7 种在铁皮石斛内生细菌研究中未被报道的菌株,其最相似物种分别为Pantoea cypripedii、Bacillus stercoris、Microbacterium hatanonis、Pseudomonas rhodesiae、Luteibacter jiangsuensis、Janibacter melonisPantoea agglomerans,其中 M. hatanonisL. jiangsuensis 首次在兰科植物中被发现. 内生细菌中 Bacillus velezensis J-15 的抑菌效果最为显著,故此对该菌株抑菌部位开展化学分离并纯化得到 3 个化合物,鉴定为:uracil (1)、3, 4-二氢-4-羟基萘-2-羧酸 (2) 和 epichlicin (3),化合物 23 是首次从该菌株发酵液中获得,抑菌活性筛选结果表明 epichlicin 对白色念珠菌具有抑菌活性.

     

    Abstract: This paper aims to isolate endophytic bacteria from the stems of Dendrobium officinale and explore their antibacterial activity and secondary metabolites. In this study, the traditional symbiotic bacteria separation method was improved, and 16S rRNA gene sequencing technology was used for identification. The antibacterial experiments of symbiotic bacteria and their fermentation crude extracts were carried out by confrontation method and filter paper diffusion method. Finally, the secondary metabolites of strains with excellent antibacterial activity were isolated and purified by different chromatographic techniques. As a results showed, seven strains of endophytic bacteria were newly reported from D. officinale by using the improved method. The most similar species were Pantoea cypripedii, Bacillus stercoris, Microbacterium hatanonis, Pseudomonas rhodesiae, Luteibacter jiangsuensis, Janibacter melonis and Pantoea agglomerans. Among them, M. hatanonis and L. jiangsuensis were first discovered in orchids. Bacillus velezensis J-15 has the most significant antibacterial effect in endophytic bacteria. Therefore, three compounds were isolated and purified from the antibacterial site of the strain, and identified as uracil (1), 3, 4-dihydro-4-hydroxynaphthalene-2-carboxylic acid (2) and epichlicin (3). Compounds 2 and 3 were obtained from the fermentation broth of the strain for the first time. The antibacterial activity screening results showed that epichlicin had antibacterial activity against Candida albicans.

     

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