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Characterization of Streptomyces spp. isolated from the sea surface microlayer in the Trondheim Fjord, Norway.

Hakvåg S, Fjaervik E, Josefsen KD, Ian E, Ellingsen TE, Zotchev SB - Mar Drugs (2008)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. sigrid.hakvag@biotech.ntnu.no

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.

Show MeSH
Growth of isolated actinomycetes after 7 days of incubation at 30 °C on ½ ISP2 agar with (A) and without (B) 50% seawater.
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f1-md-06-00620: Growth of isolated actinomycetes after 7 days of incubation at 30 °C on ½ ISP2 agar with (A) and without (B) 50% seawater.

Mentions: Cultivation of the isolates on agar medium with and without seawater, showed that they all grew better/faster on media with 50 % seawater added, as exemplified on Figure 1. Actinomycetes isolated from marine sediments have earlier been analyzed for their seawater requirement for growth [16]. The detected requirement has been interpreted as indication of marine origin or marine adaptation. None of the isolates in this study demonstrated inhibited growth on salt-containing media, suggesting that all isolates are marine bacteria or terrestrial bacteria adapted to the marine environment, and presumably occur naturally in the surface microlayer.


Characterization of Streptomyces spp. isolated from the sea surface microlayer in the Trondheim Fjord, Norway.

Hakvåg S, Fjaervik E, Josefsen KD, Ian E, Ellingsen TE, Zotchev SB - Mar Drugs (2008)

Growth of isolated actinomycetes after 7 days of incubation at 30 °C on ½ ISP2 agar with (A) and without (B) 50% seawater.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2630845&req=5

f1-md-06-00620: Growth of isolated actinomycetes after 7 days of incubation at 30 °C on ½ ISP2 agar with (A) and without (B) 50% seawater.
Mentions: Cultivation of the isolates on agar medium with and without seawater, showed that they all grew better/faster on media with 50 % seawater added, as exemplified on Figure 1. Actinomycetes isolated from marine sediments have earlier been analyzed for their seawater requirement for growth [16]. The detected requirement has been interpreted as indication of marine origin or marine adaptation. None of the isolates in this study demonstrated inhibited growth on salt-containing media, suggesting that all isolates are marine bacteria or terrestrial bacteria adapted to the marine environment, and presumably occur naturally in the surface microlayer.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Biotechnology, Norwegian University of Science and Technology, N-7491 Trondheim, Norway. sigrid.hakvag@biotech.ntnu.no

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.

Show MeSH