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目的:对中国西南地区7种石斛植物的内生真菌进行抗菌活性筛选,考察活性菌株之间的遗传关系。方法:采用组织块法分离真菌,琼脂扩散法进行抑菌活性筛选,通过rDNA的ITS序列为基础鉴定活性真菌,用邻接法(NJ)和最大简约法(MP)进行遗传关系考察。结果:从7种石斛属植物分离到98株真菌,它们对Escherichia coli,Bacillus subtilis,Staphylococcus aureus,Candida albicans,Cryptococcus neoformans和Aspergillus fumigatus的抑制率分别是1.02%,102%,184%,1.02%,1.02%,10.2%,其中DL-3,DL-18,DL-21,DM-2,DG-10和DN-1显示出了对B.subtilis,S.aureus和A.fumigatus较强的生长抑制性。24株活性真菌隶属于7个目,11个属,14个种,NJ和MP系统树阐明活性菌之间的亲缘关系。结论:本研究对于考察珍惜濒危石斛属植物的内生真菌的生物活性以及它们之间的遗传关系具有重要的生态价值,为石斛根茎部活性真菌的研究提供参考。
Objective: To screen antibacterial activity of endophytic fungi of seven species of Dendrobium in southwest China and investigate the genetic relationship among the active strains. Methods: The fungi were isolated by tissue block method and the antibacterial activity was screened by agar diffusion method. The active fungi were identified based on ITS sequence of rDNA. The genetic relationship was examined by using the NJ method and the MP method. Results: The 98 fungi were isolated from seven species of Dendrobium. The inhibitory rates of Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus were 1.02%, 102%, 184%, 1.02% 1.02% and 10.2% respectively. Among them, DL-3, DL-18, DL-21, DM-2, DG-10 and DN-1 showed strong growth inhibition on B. subtilis, S. aureus and A. fumigatus Sex. The 24 active fungi belonged to 7 orders, 11 genera and 14 species. The NJ and MP phylogenetic trees clarified the genetic relationship among active bacteria. Conclusion: This study is of great ecological value for the investigation of the biological activity of endophytic fungi that cherish endangered Dendrobium and the genetic relationship between them, and provide reference for the research of active fungi in rhizome and stem of Dendrobium.