中国西南7种石斛植物活性内生真菌及其遗传关系(英文)

Antimicrobial activity of endophytic fungi isolated fromDendrobium species in Southwestern China

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 isolate and characterize endophytic fungi from seven Dendrobium species, and detect their antimicrobial activities. Method： Fungal endophytes were isolated by strictly sterile sample preparation and fungal identification methods were based on their ITS ribosomal DNA （ ITS rDNA gene） sequences. The agar well diffusion method was then employed to evaluate the antimicrobial activity against six pathogenic organisms and the phylogenetic tree of active isolates was constructed by the MEGA. Result： Ninety-eight endophylic fungi obtained from seven Dendrobium spp. , and among them twenty-four isolates, representing 11 genera and 14 species, displayed anti-microbial activities. The phylogenetic assay based on ITS-rDNA showed that 24 active isolates were sorted to 7 taxonomic orders ： Hypocreales, Sordariales, Capnodiales, Eurotiales, Botryosphaeriales, Xylariales and Mucorales. The results of antimicrobial activity assay revealed that 1.02%, 10. 2%, 18.4%, 1.02%, 1.02% and 10. 2% of fermentation broths of 98 isolates displayed significant antimicrobial activities against E. coli , B. subtilis , S. aureus , C. albicans , C. neoformans and A. fumigatus , respectively. Four strains DL-R-3, DL-S-6, DG-R-10 and DN-S-1 displayed strong and broad antimicrobial spectrum. Conclusion： Endophytic fungi associated with Dendrobium species have fungal diversity, and possess diverse antimicrobial activity.