title: Characterization of Streptomyces spp. isolated from the sea surface microlayer in the Trondheim Fjord, Norway.
abstract: The water surface microlayer is still poorly explored, although it has been shown to contain a high density of metabolically active bacteria, often called bacterioneuston. Actinomycetes from the surface microlayer in the Trondheim fjord, Norway, have been isolated and characterized. A total of 217 isolates from two separate samples morphologically resembling the genus Streptomyces have been further investigated in this study. Antimicrobial assays showed that about 80% of the isolates exhibited antagonistic activity against non-filamentous fungus, Gram-negative, and Gram-positive bacteria. Based on the macroscopic analyses and inhibition patterns from the antimicrobial assays, the sub-grouping of isolates was performed. Partial 16S rDNAs from the candidates from each subgroup were sequenced and phylogenetic analysis performed. 7 isolates with identical 16S rDNA sequences were further studied for the presence of PKS type I genes. Sequencing and phylogenetic analysis of the PKS gene fragments revealed that horizontal gene transfer between closely related species might have taken place. Identification of unique PKS genes in these isolates implies that de-replication can not be performed based solely on the 16S rDNA sequences. The results obtained in this study suggest that streptomycetes from the neuston population may be an interesting source for discovery of new antimicrobial agents.
authors.affiliation: Department of Biotechnology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. sigrid.hakvag@biotech.ntnu.no
authors.forename: Sigrid
authors.initials: S
authors.lastname: Hakvåg
authors.forename: Espen
authors.initials: E
authors.lastname: Fjaervik
authors.forename: Kjell D
authors.initials: KD
authors.lastname: Josefsen
authors.forename: Elena
authors.initials: E
authors.lastname: Ian
authors.forename: Trond E
authors.initials: TE
authors.lastname: Ellingsen
authors.forename: Sergey B
authors.initials: SB
authors.lastname: Zotchev
mesh_terms: D000890:Anti-Infective Agents / Q000302:isolation & purification / Q000494:pharmacology*; D001483:Base Sequence; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D005658:Fungi / Q000187:drug effects; D022761:Gene Transfer, Horizontal; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D009664:Norway; D048630:Polyketide Synthases / Q000235:genetics* / Q000302:isolation & purification; D012623:Seawater / Q000382:microbiology; D013302:Streptomyces / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D014871:Water Microbiology
chemical_list: D000890:Anti-Infective Agents; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D048630:Polyketide Synthases