title: Antitumour and antimicrobial activities of endophytic streptomycetes from pharmaceutical plants in rainforest.
abstract: OBJECTIVE
  The aim of this study was to screen antitumour and antimicrobial activities of endophytic actinomycetes isolated from pharmaceutical plants in rainforest in Yunnan province, China.
  
  
  RESULTS
  Antitumour activity was studied by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and antimicrobial activity was determined by agar well diffusion method. The high bioactive endophytic isolates were identified and further investigated for the presence of polyketide synthases (PKS-I, PKS-II) and nonribosomal peptide synthetases (NRPS) sequences by specific amplification. The molecular identification confirmed that the 41 isolates showed significant activities were members of the genus Streptomyces. Among them, 31.7% of endophytic streptomycete cultures were cytotoxic against A549 cells, 29.3% against HL-60 cells, 85.4% against BEL-7404 cells, 90.2% against P388D1 cells, 65.9% were active against Escherichia coli, 24.4% against Staphylococcus aureus, 31.7% against Staphylococcus epidermidis, 12.2% against Candida albicans and no strain displayed antagonistic activity against Klebsiella pneumoniae. High frequencies of positive PCR amplification were obtained for PKS-I (34.1%), PKS-II (63.4%) and NRPS (61.0%) biosynthetic systems.
  
  
  CONCLUSIONS
  Many endophytic streptomycetes isolated from pharmaceutical plants in rainforest possess remarkable and diverse antitumour and antimicrobial bioactivities.
  
  
  CONCLUSIONS
  These endophytic streptomycetes are precious resources obtained from rainforests, and they could be a promising source for bioactive agents.
authors.affiliation: The Key Laboratory for Microbial Resources of the Ministry of Education, Yunnan Institute of Microbiology, Yunnan University, Kunming, China.
authors.forename: J
authors.initials: J
authors.lastname: Li
authors.forename: G-Z
authors.initials: GZ
authors.lastname: Zhao
authors.forename: H-H
authors.initials: HH
authors.lastname: Chen
authors.forename: H-B
authors.initials: HB
authors.lastname: Wang
authors.forename: S
authors.initials: S
authors.lastname: Qin
authors.forename: W-Y
authors.initials: WY
authors.lastname: Zhu
authors.forename: L-H
authors.initials: LH
authors.lastname: Xu
authors.forename: C-L
authors.initials: CL
authors.lastname: Jiang
authors.forename: W-J
authors.initials: WJ
authors.lastname: Li
mesh_terms: D000890:Anti-Infective Agents / Q000494:pharmacology*; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001419:Bacteria / Q000187:drug effects; D045744:Cell Line, Tumor; D002681:China; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D010946:Plants, Medicinal / Q000382:microbiology*; D013302:Streptomyces / Q000737:chemistry* / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D014329:Tropical Climate
chemical_list: D000890:Anti-Infective Agents; D000970:Antineoplastic Agents