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  • 1
    Keywords: Hochschulschrift
    Type of Medium: Online Resource
    Pages: 1 Online-Ressource (89 Seiten = 5 MB) , Illustrationen, Graphen
    Edition: Online-Ausgabe 2022
    Language: English
    Note: Zusammenfassung in deutscher und englischer Sprache
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  • 2
    Publication Date: 2017-01-17
    Description: The majority of marine natural products (MNPs) originate from tropical and temperate shallow water invertebrates, such as sponges [1]. Recent studies indicate the presence of great genetic diversity in deep-waters that may be linked to unprecedented chemistry due to evolution/adaptation to extremely harsh environmental conditions. However, only less than 2% of MNPs derive from the deep-sea organisms [2]. Antarctic ecosystems are rich in biodiversity [3] and exposed to unique environmental characteristics resulting in communities structured both by biotic interactions (e.g. predation, competition) and abiotic factors (e.g. seasonality, ice-scouring) [4], suggesting a high chemical diversity. In this work, we investigated 39 deep-water sponges collected from the Antarctic Weddell Sea and adjacent areas (depths -100 – 600 m). The freeze-dried sponge samples were extracted with water, followed by MeOH and CH2Cl2 separately. The combined organic extracts were tested for activity against cancer cells [HepG2 (liver) and HT29 (bowel) cancer cell lines], bacteria [ESKAPE panel: Enterococcus faecalis, Staphylococcus aureus (MRSA), Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Escherichia coli) and fungi (yeasts Candida albicans, Cryptococcus neoformans). Several Latrunculia sponge extracts displayed high anticancer activity against both cell lines (IC50 values 0.50 – 3.16 µg/ml). The organic extract of the glass sponge Rossella cf. antarctica showed moderate antibiotic activity towards MRSA and E. faecalis with IC50 values of 96 and 213 µg/ml, respectively. All extracts have undergone chemical profiling/dereplication studies by HPLC-DAD-MS and 1H NMR spectroscopy. The results of chemical and biological screening will assist in selection and activity-guided isolation of Antarctic deep-water sponge metabolites.
    Type: Article , NonPeerReviewed
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  • 3
    Publication Date: 2022-01-31
    Description: Zostera marina (eelgrass) is a marine foundation species with key ecological roles in coastal habitats. Its bacterial microbiota has been well studied, but very little is known about its mycobiome. In this study, we have isolated and identified 13 fungal strains, dominated by Penicillium species (10 strains), from the leaf and the root rhizosphere of Baltic Z. marina. The organic extracts of the fungi that were cultured by an OSMAC (One-Strain–Many-Compounds) regime using five liquid culture media under both static and shaking conditions were investigated for their chemical and bioactivity profiles. All extracts showed strong anti-quorum sensing activity, and the majority of the Penicillium extracts displayed antimicrobial or anti-biofilm activity against Gram-negative environmental marine and human pathogens. HPLC-DAD-MS-based rapid metabolome analyses of the extracts indicated the high influence of culture conditions on the secondary metabolite (SM) profiles. Among 69 compounds detected in all Penicillium sp. extracts, 46 were successfully dereplicated. Analysis of SM relatedness in culture conditions by Hierarchical Cluster Analysis (HCA) revealed generally low similarity and showed a strong effect of medium selection on chemical profiles of Penicillium sp. This is the first study assessing both the metabolite and bioactivity profile of the fungi associated with Baltic eelgrass Z. marina.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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  • 4
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    In:  (Master thesis), Christian-Albrechts-Universität zu Kiel, Kiel, Germany, 97 pp
    Publication Date: 2022-01-18
    Description: A powerful data mining tool was developed which allows detailed analysis of microbial metabolite fingerprints. This approach was applied to HRMS data obtained from the fermentation of eight actinomycetes treated with subinhibitory concentrations of six different antibiotics in order to monitor stimulations in secondary metabolite production. Each strain was fermented in medium containing a) no antibiotic b) a quarter of its specific MIC (MIC/4) and c) a 400 fold dilution of its MIC (MIC/400). The production of 21 ions was stimulated as response to antibiotic exposure. All of them were characterized as specific adduction products (as consequence of the ionisation process) and their predicted molecular formula was compared with formulas of known compounds. A portion of 9 identified adducts could not be found in commercial databases and is considered to be putatively new. Chloramphenicol, penicillin G and actinomycin D induced most secondary metabolites in the selected actinomycete strains and therefore might be considered for further research. Known effects like the expression of silent genes coding for the siderophore ferrioxamine, the enhanced expression of streptophenazines in response to antibiotic treatment and the stimulation of many unidentified compounds was demonstrated. Additionally it was shown that Kitosatospora griseola MF730-N6 is capable of performing the glycosylation of the ionophor nigericin. It could be demonstrated that the supplementation of subinhibitory concentrations of antibiotics to actinomycete fermentations can activate silent gene cluster expression and is therefore a valuable technique in drug discovery programs. The results of this study represent the unexplored potential and hidden metabolic capacity of both new and well-studied organisms.
    Keywords: Course of study: MSc Biological Oceanography
    Type: Thesis , NonPeerReviewed
    Format: text
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