Antimicrobial activity of endophytic fungi isolated from Dendrobium species in southwestern China.
OBJECTIVE
To isolate and characterize endophytic fungi from seven Dendrobium species, and detect their antimicrobial activities.


METHODS
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.


RESULTS
Ninety-eight endophytic 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.


CONCLUSIONS
Endophytic fungi associated with Dendrobium species have fungal diversity, and possess diverse antimicrobial activity.
Institute of Medicinal Plant Development, Chinese Academy of Medical Sciences Peking Union Medical College, Beijing 100193, China.
Jinlong
J
Cui
Yunqiang
Y
Wang
Yongmei
Y
Xing
Shunxing
S
Guo
Peigen
P
Xiao
Mengliang
M
Wang
D000890:Anti-Infective Agents / Q000378:metabolism / Q000494:pharmacology*; D001232:Aspergillus fumigatus / Q000187:drug effects; D001412:Bacillus subtilis / Q000187:drug effects; D001483:Base Sequence; D044822:Biodiversity; D002176:Candida albicans / Q000187:drug effects; D002681:China; D003455:Cryptococcus neoformans / Q000187:drug effects; D004271:DNA, Fungal / Q000737:chemistry / Q000302:isolation & purification; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D031667:Dendrobium / Q000382:microbiology* / Q000502:physiology; D060026:Endophytes / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology; D004926:Escherichia coli / Q000187:drug effects; D005658:Fungi / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D018517:Plant Roots / Q000382:microbiology / Q000502:physiology; D018547:Plant Stems / Q000382:microbiology / Q000502:physiology; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013211:Staphylococcus aureus / Q000187:drug effects
D000890:Anti-Infective Agents; D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer