title: Molecular, chemical and biological screening of soil actinomycete isolates in seeking bioactive peptide metabolites.
abstract: OBJECTIVE
  Due to the evolution of multidrug-resistant strains, screening of natural resources, especially actinomycetes, for new therapeutic agents discovery has become the interests of researchers. In this study, molecular, chemical and biological screening of soil actinomycetes was carried out in order to search for peptide-producing actinomycetes.
  
  
  METHODS
  60 actinomycetes were isolated from soils of Iran. The isolates were subjected to molecular screening for detection NRPS (non-ribosomal peptide synthetases) gene. Phylogenic identification of NRPS containing isolates was performed. Chemical screening of the crude extracts was performed using chlorine o-dianisidine as peptide detector reagent and bioactivity of peptide producing strains was determined by antimicrobial bioassay. High pressure liquid chromatography- mass spectrometry (HPLC-MS) with UV-visible spectroscopy was performed for detection of the metabolite diversity in selected strain.
  
  
  RESULTS
  Amplified NRPS adenylation gene (700 bp) was detected among 30 strains. Phylogenic identification of these isolates showed presence of rare actinomycetes genera among the isolates and 10 out of 30 strains were subjected to chemical screening. Nocardia sp. UTMC 751 showed antimicrobial activity against bacterial and fungal test pathogens. HPLC-MS and UV-visible spectroscopy results from the crude extract showed that this strain has probably the ability to produce new metabolites.
  
  
  CONCLUSIONS
  By application of a combined approach, including molecular, chemical and bioactivity analysis, a promising strain of Nocardia sp. UTMC 751 was obtained. This strain had significant activity against Staphylococcus aureus and Pseudomonas aeruginosa. Strain Nocardia sp. UTMC 751 produce five unknown and most probably new metabolites with molecular weights of 274.2, 390.3, 415.3, 598.4 and 772.5. This strain had showed 99% similarity to Nocardia ignorata DSM 44496 T.
authors.affiliation: Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, 14155-6455, Tehran, Iran. ; Microbial Technology and Products Research Center, University of Tehran, Tehran, Iran.
authors.forename: Javad
authors.initials: J
authors.lastname: Hamedi
authors.affiliation: Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, 14155-6455, Tehran, Iran. ; Microbial Technology and Products Research Center, University of Tehran, Tehran, Iran.
authors.forename: Somaye
authors.initials: S
authors.lastname: Imanparast
authors.affiliation: Department of Microbial Biotechnology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, 14155-6455, Tehran, Iran. ; Microbial Technology and Products Research Center, University of Tehran, Tehran, Iran.
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Mohammadipanah
keywords: Actinomycetes; Molecular screening; Non-ribosomal peptide synthetases; Peptide