title: Characterization and phylogenetic analysis of novel polyene type antimicrobial metabolite producing actinomycetes from marine sediments: Bay of Bengal, India.
abstract: OBJECTIVE
  To isolate and indentify the promising antimicrobial metabolite producing Streptomyces strains from marine sediment samples from Andrapradesh coast of India.
  
  
  METHODS
  Antagonistic actinomycetes were isolated by starch casein agar medium and modified nutrient agar medium with 1% glucose used as a base for primary screening. Significant antimicrobial metabolite producing strains were selected and identified by using biochemical and 16S rDNA level. Minimum inhibitory concentrations of the organic extracts were done by using broth micro dilution method.
  
  
  RESULTS
  Among the 210 actinomycetes, 64.3% exhibited activity against Gram positive bacteria, 48.5 % showed activity towards Gram negative bacteria, 38.8% exhibited both Gram positive and negative bacteria and 80.85 % isolates revealed significant antifungal activity. However, five isolates AP-5, AP-18, AP-41 and AP-70 showed significant antimicrobial activity. The analysis of cell wall hydrolysates showed the presence of LL-diaminopimelic acid and glycine in all the isolates. Sequencing analysis indicated that the isolates shared 98.5%-99.8% sequence identity to the 16S rDNA gene sequences of the Streptomyces taxons. The antimicrobial substances were extracted using hexane and ethyl acetate from spent medium in which strains were cultivated at 30°Cfor five days. The antimicrobial activity was assessed using broth micro dilution technique. Each of the culture extracts from these five strains showed a typical polyene-like property. The lowest minimum inhibitory concentrations of ethyl acetate extracts against Escherichia coli and Curvularia lunata were 67.5 and 125.0 µg/mL, respectively.
  
  
  CONCLUSIONS
  It can be concluded that hexane and ethyl acetate soluble extracellular products of novel isolates are effective against pathogenic bacteria and fungi.
authors.affiliation: Division of Microbiology, Entomology Research Institute, Loyola College, Chennai, India.
authors.forename: Arasu M
authors.initials: AM
authors.lastname: Valan
authors.forename: K R T
authors.initials: KR
authors.lastname: Asha
authors.forename: V
authors.initials: V
authors.lastname: Duraipandiyan
authors.forename: S
authors.initials: S
authors.lastname: Ignacimuthu
authors.forename: P
authors.initials: P
authors.lastname: Agastian
mesh_terms: D039903:Actinobacteria / Q000737:chemistry* / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000494:pharmacology; D000890:Anti-Infective Agents / Q000737:chemistry / Q000494:pharmacology*; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology; D061006:Bays; D045424:Complex Mixtures / Q000737:chemistry / Q000494:pharmacology; D019015:Geologic Sediments / Q000382:microbiology*; D007194:India; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010802:Phylogeny; D011090:Polyenes / Q000737:chemistry / Q000494:pharmacology*; D012336:RNA, Ribosomal, 16S / Q000235:genetics
chemical_list: D000900:Anti-Bacterial Agents; D000890:Anti-Infective Agents; D000935:Antifungal Agents; D045424:Complex Mixtures; D011090:Polyenes; D012336:RNA, Ribosomal, 16S
keywords: 16S rDNA; Marine Streptomyces sp.; Minimum inhibitory concentration; Polyene antimicrobial activity